What is Electric Current and how it relates to Metering

What is electric current? A good question indeed. What is the unit of measure for electric current? How can we measure electric current? And finally how does it relate to metering? These are the questions that will be tackled in this post. So, let’s get started with the first one.

What is electric current?

Electric current is the flow of electrons in a circuit. It is also what is used to power our stuff. Remember that in a circuit we have both voltage and current available. But, without the current flow our electrical stuff does not move. So, now that you know that electric current is the flow of electrons in a circuit what is the unit of measure used?

What is the unit of measure?

Current is measured using what are known as amperes, or amps for short. This is typically notated as an “A” in formulas but can also be notated as an “I”. This “I” stands for intensity of current. As with any unit of measure amps can be smaller or larger. So, it is not uncommon to see milliamps or kiloamps. Milliamps is typically notated as mA and kiloamps as kA. So, now that you know the unit of measure, how do you measure amps?

How do you measure Amps?

Amps, or electric current, are measured using what is known as an ammeter. An ammeter can come in a couple of different varieties. There is the common clamp on ammeter. The clamp on ammeter comes with a spring loaded jaw that enables you to open the jaw and place it around the conductors. This places the ammeter in parallel with the circuit. Clamp on ammeters can be found in digital and analog variants.

Another type of ammeter is placed in series with the circuit. These are typically found on multimeters. Also, when an ammeter is placed in series in the circuit it typically is not able to measure a very substantial load. Make sure you read the specs on your meter before you place it in series in any circuit.

How does electric current relate to Metering?

Ah yes, finally, the meat of the article. Electric current is very important to metering. This is because we are essentially measuring the changes in current flow. Remember that using Ohm’s law and the power formula that Watts = Volts x Amps. This means that the amount of watts used are in direct proportion to the amount of current that is being used. As the amps go up, so does the watts. As the amps go down so do the watts.

We as meter techs should know how amps relates to watts and how to convert amps to watts. We should also know how to go the other way and convert watts to amps. This will help us in troubleshooting with customers. Let’s have an example.

A customer is complaining of a high bill. You go to the meter and notice it is spinning pretty fast. So, you take the cover off the meter base and check the amperage. Let’s say that it is 30 amps. How do you convert this 30 amps to watts? Using Ohm’s law we plug in the numbers. Assume this is a 240v service. W = 240 volts x 30 amps = 7,200 watts. Let’s convert that to kilowatts and divide 7,200 by 1,000. We get 7.2 kw. This means that whatever the customer has on is pulling 7.2 kw and if left on for one hour it will use 7.2 kwh. A load like this could mean that an appliance like the air conditioning is not functioning properly and is running all day.


Electric current is one of the most important units we have in metering. It is measured by using ammeters and its unit of measurement is the amp. Using Ohm’s law we can convert amps to watts and back again.

What is Voltage and how it relates to Metering

What is voltage? This is certainly an important term to know in the electrical field. You hear it all the time. What is the voltage on the machine? Or, can you check the voltage on that circuit? We hear it, we say it but, what is voltage and how does it relate to metering?

What is voltage?

The most commonly used voltage definition states that voltage is the difference in potential between two points in a circuit. What a definition of voltage right? Another way that voltage is defined is by talking about water. Some find it easier to understand the voltage definition when we talk in terms of water pipes. Voltage is the driving force in an electrical circuit. We can think of it as the pressure in the circuit. So, what is voltage? It is the driving force in an electrical circuit.

How is voltage measured?

Voltage is measured using a voltmeter. With a voltmeter we can choose two different points in the circuit to measure the difference in potential across those two points. The unit of measure for voltage is known as the volt. The volt is named after Alessandro Volta who created the first battery known as a voltaic pile.

How does voltage relate to metering?

Ah yes, the big question is, how do we use voltage in metering? Well, we have to remember that meters measure kilowatts. So, what does that have to do with voltage? To find the kilowatts, we first need to find the watts. To calculate watts we need to know the current and the, you guessed it, voltage. Using Ohm’s Law we know that power is equal to voltage times current or stated mathematically, P = I x E. There are several ways you can remember this formula. One is by remembering the word PIE. Another is to change the letters to W = V x A.

In the first example, P = power measured in watts, I = current measured in amps, and E = voltage measured in volts. Just a quick fact here, E is the letter used because it stands for electromotive force which is a fancy way to say voltage.

In the second example, W = watts, V = voltage, A = amps. So, the two equations are equal they are just using different terms. The easy way to remember W = V x A is to think of West Virginia or W VA. Pretty simple right.

So, now that we know the terms we need to know how they relate to metering. Well, the nominal voltage in a typical metering circuit remains pretty much constant. A common household voltage is 120/240. So, the meter measures this voltage and then multiplies the voltage times the current in the circuit to get watts. And then as if by magic the readout is in kilowatts.


Look at the equations again and go back to algebra I. If the voltage stays constant and the amperage goes up that means that the wattage will go up. If the amperage goes down, the wattage goes down. To get kilowatts from watts, divide the watts by 1000. In the older electromechanical meters the voltage coil, also known as potential coil, produced a magnetic field in the meter. When current flows through the meter it produces a magnetic field as well. The interaction between these two fields are what causes the disc to turn. So this is why it is important to make sure that the meter chosen for each installation is crucial.


Voltage is the driving force behind each and every electrical circuit. We can use Ohm’s law to calculate watts using the power formula. It is the interaction of voltage and current in a circuit that causes the meter disc to spin. To check the voltage in a circuit we use what is called a voltmeter.

Portable Generators – All Your Neighbors Will be Jealous as they Sit in the Dark

Portable generators are becoming a very popular way to keep the power on. There are many things that can knock the power out. The biggest being storms. Whether they are ice storms, thunderstorms or just plain windstorms, a power outage can be a major inconvenience. So what do you do? You go shopping for a portable generator. But, with all of the choices available where do you start? How many watts do you need? Do you need 120v or 240v? How do you connect it to your house?  Read on as we tackle these questions.

Check out this great way to harness electricity from the Sun!

When Shopping for Portable Generators, where do you Start?

If you are keen on making your neighbors jealous when their power is out and yours is not, you need to start shopping and buy your portable generator before the storm. So, that is the first place to start. Make sure that you are not waiting on the natural disaster to begin shopping. Prices can be higher during a natural disaster and supplies may be limited.

You can do your shopping at many of the big box hardware stores or even online at sites like Amazon. There are several things that you need to consider when buying a portable generator. The biggest two are watts and voltage. When looking at these quantities you need to first decide what it is that you want to power when the power is out. Which leads us to our next point.

How many Watts do you Need?

To decide how many watts your portable generator needs to put out you first need to decide what you want to power. Do you want just lights so you can see at night? Does your refrigerator need to have power so your food does not spoil? Do you want to have heat? These are all considerations to take into account when deciding how many watts you need. All of your appliances have wattage ratings. So, decide what you want to power and then go and check the ratings of each appliance.

After you have checked the wattage ratings of your appliances add them up. This will give you the amount of wattage that your generator needs to put out. A word of caution here. Most people want to power their entire homes with a portable generator. While there are some models that are capable of doing this for smaller homes, that is not their intention. The intention is to run critical loads or essential loads. These are the loads that are most essential. If you live in a very cold climate your heating system may be a critical load. Most people choose their refrigerator and a few sets of lights as critical loads.

Should you buy a 120v or 240v Portable Generator?

The answer here depends on what you have chosen as your critical loads. If they are all 120v, such as lights and the refrigerator, then a 120v generator will work just fine. If you are wanting to power your heating system, water heater, or stove then you should consider a 240v generator. Some well pumps are also 240v. So, if you need to power a well pump you need to check the voltage of it as well.

How do you connect your Portable Generator to your House?

Connecting portable generators to your house is a job for a licensed electrician. They will install a transfer switch along with new breakers for the essential loads that you choose. This ensures that when the power does go out and you use your generator that no power will be put back on the grid. Keeping your generator power separated from grid power keeps the lineman safe.

Do not just fashion a drop cord with two ends that plug in and plug it into the wall. First of all this is illegal. Second, you can put power back on the grid this way and cause serious injury or death to someone working on the power lines. Also, if you do this you will try to run your whole house off of it. The extension cord is not rated for this and neither is the receptacle that you have it plugged into. You can burn your house down doing this.

This should be a no brainer, but make sure your portable generator is outside when using it. The exhaust from the generator can be deadly.


Portable generators can be a great addition to your home. They can keep the lights on and make your neighbors jealous. They can also be used to make sure that your food does not spoil during a storm. Make sure that when you are deciding what you want to power that you add up the wattage of each appliance. Then decide if you need a 120v or a 240v generator. Finally, once you have made your purchase, contact a licensed electrician to get everything installed in a safe and professional way.


Truper Automatic Wire Stripper Review

An automatic wire stripper can really add to your arsenal of electric tools. The ability to quickly, easily and cleanly strip wire can increase your productivity and reduce waste. Until the automatic wire stripper came about, you really had two options. You could use your knife to strip wire, or you could use a regular wire stripper like the Klein Tools 11047 Wire Stripper/Cutter. What I want to do is give my review of the Truper Automatic Wire Stripper.

Truper Automatic Wire Stripper

truper automatic wire stripperThese wire strippers can be used to skin wire from 22 AWG – 10 AWG. This gives you a very wide range of wire sizes to choose from. And the best thing about them is that they are automatic. This means that you will not need to squint really hard to see which hold in your regular wire strippers you need to use. You just lay the wire in there and squeeze. That’s it!

I have used normal wire strippers for most of my career. I have also used a knife to skin wire for most of my career as well. So, when I bought these automatic wire strippers I was a bit skeptical. But, they really do a great job of stripping the wire.


truper automatic wire stripper jawsThe Truper automatic wire stripper features a guide that can be set up so all of your strips are the same length. This can be very useful for really anything you are doing. If you are making up a panel and you want all of your strips to be the same length so that just the right amount of bare wire is under the connector, you can do that. All you have to do is move it until you get the right length. Then set it and forget it. It really is that easy.

These automatic strippers also feature a wire cutter. However, it is not the best. It is located between the handles so you do not get a ton of leverage. When I was using them there were a few times where it did not cut all the strands of the stranded wire I was working with. But, these are not really made for cutting wire, they are made for stripping wire. If you are looking to cut wire then check out my review of the Truper Lineman’s Pliers.

Another feature of the this automatic wire stripper is the ability to crimp wire. It offers three different positions for crimping. Again, these are in the middle of the handles. I have never had good luck with any strippers or wire crimpers where the stripping, cutting or crimping is in between the handles.

The grips on these automatic wire strippers are comfortable. They offer plenty of leverage to carry out fast and precise wire strips.


The Truper Automatic Wire Stripper is a tool I wish that I would have had many years ago when I started in the meter field. I think about all of those meter bases I have wired up through the years where I used my knife or regular wire strippers to skin the wire. All of those CT’s and PT’s that I have wired up through the years could have been done much faster.

I highly recommend this tool. After using this tool on the first job you will not regret buying it. It makes stripping wire practically effortless.

Truper Heavy Duty Lineman’s Pliers Review

Lineman’s pliers are one of the most important hand tools in a meter tech’s arsenal of tools. A good set of lineman’s pliers allows you to cut and bend wire with ease. They also need to be durable enough to be used at times as a hammer. Now, trust me I know that they are not a hammer but can you honestly tell me that you have never used your pliers to beat on something? One of the things that meter techs use lineman’s pliers for is cutting meter seals. Most of these types of meter seals have a steel wire which is harder than copper. This means that the pliers must be up to the task of cutting the steel day in and day out.

Now, I know that the Klein Tools 9-Inch High Leverage Side Cutting Pliers are pretty much the standard in the electrical field. But what if you need a set of pliers that work just as well but are different than everyone else? Are there any options out there?

Truper Heavy Duty Lineman’s Pliers

Truper Heavy Duty Lineman's Pliers

Truper is not a new company but it is not as well known in the electrical field as names like Klein, Greenlee and Ideal. But, they do make a good set of lineman’s pliers. Their 9″ heavy duty pliers are made of forged chrome vanadium steel which is supposed to be two times stronger than carbon steel. They also feature a good comfortable grips. The finish on the pliers is a satin finish which helps with rust resistance.

My Review

Truper Heavy Duy Pliers LengthSo, what do I think about the Truper Heavy Duty Lineman’s Pliers? All in all I think that they are a good tool for any toolbox out there. I do not think that you would be disappointed if you made the purchase. Now, there are a couple of things that I would like to mention about these pliers. The overall length is about 9.5″. The distance from the pivot point to the end of the handle is about 7.5″. This means that you get good leverage when using these pliers.

The grips are comfortable and they offer a raised portion to help aid in holding on to the pliers. I also feel like this helps keep your hands from slipping if you need to use the pliers to push something as well. I also want to note that the grips are not for use on live circuits. So, keep that in mind when using these pliers. I have used Klein Pliers most of my career and one difference that I notice between these and the Klein are that the head of Truper pliers seems to be larger. That could be a good thing if you are using the pliers to bang on things because of the added mass. It could also be bad if you need to get into tight spaces.

My biggest complaint with the pliers is the jaw design. You can see in the picture below what I am talking about. Just below the cutters there is a gap when the jaw open. More than once while using these pliers to cut wire the wire has fallen into that gap. This prevents you from cutting the wire because the gap portion clamps down on wire. Once you get used to it, there is no problem. Just something I though I would point out.Truper heavy duty lineman's pliers jaw


Would I buy the Truper Heavy Duty Lineman’s Pliers? The answer is yes. Although they are not perfect they are perfectly capable of handling any task with ease. Whether it be cutting, bending, pulling wire or wiring up CT’s these pliers get the job done.

Increasing Revenue with High Accuracy CT’s

Increasing revenue is something that we all want to do. High accuracy CT’s can help us achieve that goal. When it comes to instrument rated metering installations we have to remember that our meter is only as accurate as our CT’s. So, the first step in making sure we are accurately measuring our metering installations is making sure we have the most accurate CT’s installed.

Standard Vs. High Accuracy

This is where high accuracy CT’s come into play. Remember that standard current transformers are only guaranteed accurate to within 0.3% from the nameplate value to the rating factor. Also, standard CT’s are 0.6% accurate from 10% of the nameplate value up to the nameplate value. This means that for a common 600:5 CT that anything below 60 amps is not guaranteed to be measured accurately. So, what do you do?

You install a high accuracy CT that is 0.15% accurate from 5% of its nameplate rating through the rating factor. Now, using the same 600:5 ratio as an example, we are now able to measure down to 30 amps with 0.15% accuracy. This is high accuracy CT’s are used to help with increasing revenue.

Where can high accuracy CT’s help with increasing revenue?

One of the places where high accuracy CT’s can help with increasing revenues are department stores or industrial factories that have been converted to warehouse space. These types of customer changes can cause revenue losses because the infrastructure that was put in for these larger customers who have now left or have converted their spaces is no longer being utilized.

Let’s say that the customer was doing some small scale manufacturing and decided that the space was no longer big enough for its manufacturing needs. So, they decide to move into a larger space and convert this previous space into warehousing. Let’s keep with the standard 600:5 for this example. For this example let’s also assume that the rating factor of this standard CT was three. We are also going to assume that we were using this rating factor. Meaning that this was a 1200 amp service and we installed 600:5 CT’s with a rating factor of 3, to make sure that the CT’s were as saturated as possible.

The customer in this example typically pulls around 750-800 amps. This is well within the range of our standard accuracy 600:5 CT’s. Now when they leave, they take all of the manufacturing equipment with them and only leave a few lights. There new load is now only around 40 amps. They do not need to heat or cool the space because what they are storing does not require it. So now, the standard 600:5 CT is not guaranteed to measure the 40 amps accurately.

What if we had installed a high accuracy CT?

If we had installed a high accuracy CT to begin with then we would not be worried. The high accuracy 600:5 CT is able to measure down to 30 amps with 0.15% accuracy. This means we capture those 40 amps and we do so accurately. This is how high accuracy CT’s play a vital role in increasing revenue.


In conclusion, if you are concerned with increasing revenue make sure that you are giving a look to high accuracy CT’s. They can be placed anywhere your standard accuracy CT’s are and can instantly start increasing revenue. High accuracy CT’s help mitigate low current situations such as when large customers move out or convert. If you are in the market for high accuracy CT’s check out Peak Demand.

Reducing Inventory with High Accuracy CTs

Reducing inventory is a big concern with utilities these days. This is primarily driven by the fact that reducing inventory means reduced costs. Reducing costs means that the profit margin can be higher. So, what does that have to do with high accuracy CT’s? How can high accuracy CT’s reduce inventory?

Use the Extended Range of High Accuracy CT’s

When placing new CT’s in service we traditionally had a variety of different CT ratios to choose from. Among the most popular are 200:5, 400:5 and 600:5 variants. This means that when a new service is built the meter tech or engineer will look at the service and size the CT’s according to the projected load. This is done because we want the amps on the service as close to the nameplate rating as possible. We do this because standard CT’s are most accurate at their nameplate rating up to their rating factor.

So, if we have a 400 amp service that is projected to normally run around half of that or less we may use 200:5 CT’s with a rating factor of at least two. This ensures that when the amperage is low we can measure it as accurately as possible.

Enter the new kid on the block. The high accuracy CT. With the high accuracy CT, with its extended range features we can now use one size CT for most of our installations. For instance a 600:5 high accuracy CT will allow us to measure down to 30 amps. But there is more. Many manufacturers are offering these high accuracy CT’s with extended ranges that can measure down even further.

How can High Accuracy CT’s be useful in Reducing Inventory?

High accuracy CT’s can reduce inventory by reducing the number of different ratios that you need. You can now purchase a 600:5 CT with a rating factor of 2 or more that can cover all your needs. This means that you no longer need to use 200:5 or 400:5 CT’s. You can stock one size. This allows you to purchase less. Even if you do not have a new job coming up, in the past you would have needed to keep a certain number of 200:5 and 400:5 CT’s on the shelf for emergencies.

So, instead of having a couple of sets of each size, you can have just a couple of sets of 600:5 CT’s that can be used for each service type. Instead of having purchased four sets of CT’s now you have only purchased two. This is beneficial to reducing inventory and cutting costs. Also, it leads to a reduction in storage space as well.


High accuracy CT’s can be a great way of reducing inventory in your meter shop or warehouse. Look at what you have stored in your warehouse and see if you could benefit from reducing the number of CT’s that are just sitting on the shelf as spares. If you are interested in high accuracy CT’s check out the offerings from Peak Demand.

Extended Range CTs VS High Accuracy CTs

Extended range CT’s are all the rage with CT sales people now. But what exactly are they? Don’t we already have high accuracy CT options out there? Is there a difference in extended range CTs and high accuracy CTs? I will try and break these terms down and explain what the difference is between extended range CTs and high accuracy CTs.

What are Extended Range CTs?

To understand what extended range CTs are we need to understand what standard range CTs are. Standard range CTs have a measurement range from 0 amps through their rating factor. However, notice that I said measurement and not accuracy. That is because if we remember correctly that standard CTs are only certified as being accurate to 0.6% from 10% of their nameplate rating through the nameplate rating. Furthermore, at the nameplate rating up through the rating factor they are accurate to within 0.3%.

So, obviously an extended range CT would be better than that right? Well, yes. However, there is a caveat. That being that there is no standard when it comes to the term “extended range CT.” These extended ranges are noted in the literature that comes from the manufacturer of the CT. This means that the CT could be accurate down to 3% of the nameplate value or even down to 1%. This however all depends on the manufacturer. Which leads us to our next point.

Don’t we Already Have High Accuracy CTs?

The answer to that question is yes. But let’s remember that to be classified as a high accuracy CT that there are certain guidelines that must be adhered to. The IEEE is the body that defines that standard. If you want to learn more about high accuracy CTs follow the link. So the next question then is why do we have extended range CTs if high accuracy CTs already exist and is there a difference?

What is the difference between extended range CTs and high accuracy CTs?

The first difference is that high accuracy CTs actually have a standard that must be met to be called high accuracy. Extended range CTs however do not have this standard. However, most extended range CTs are high accuracy CTs. The reason for this is because manufacturers need a way to separate themselves from the competition. It is not good enough for them to just meet the standard. They need to go above and beyond the standard to attract more customers.

This is good for utilities because it means that in the end they have access to more choices and better products. Utilities who want high accuracy CTs will find that not only are they available but they are available with more extended ranges than the standard requires. Just remember also that an extended range CT is not always high accuracy. Check and make sure that the CT has a rating for high accuracy before believing the salesman. Extended range is something that the manufacturer decides.


Extended range CTs can be used anywhere standard CTs are used. They allow you the ability to meter lower levels of current than you would have before now. This also permits greater revenue over the life of the CT. However, make sure that the CT is high accuracy before you jump on the extended range bandwagon.

What are High Accuracy CT’s?

High accuracy CT’s are becoming more and more popular with utilities these days. Because of new manufacturing processes and materials, manufacturers such as Peak Demand are now able to make their CT’s more accurate. But, more accurate than what? Just saying that a CT is high accuracy still does not tell us what it is. So, what is a high accuracy CT?

What is a Standard Accuracy CT?

To understand what makes a CT “high accuracy,” we first need to know what the standard accuracy of a revenue grade CT is. To be classified as a revenue grade CT the IEEE states that it must be a Class 0.3. Well, that really does not tell us much. Class 0.3 means that the CT must be accurate to within 0.3% of the nameplate rating up to the rating factor.

We can use a common Class 0.3,  600:5 CT with a rating factor of 2 to create an example. From the nameplate value of 600 amps all the way up to 1200 amps when using the rating factor, the CT has to be accurate to within 0.3%. However, below 600 amps, more specifically from 10% of 600, which is 60 amps, all the way to 600 amps the CT only has to be 0.6% accurate. Below 60 amps the accuracy is not guaranteed. Thus the need for a higher accuracy solution.

What is a High Accuracy CT?

A high accuracy CT is a Class 0.15S. This means that the CT must be accurate to within 0.15%, but there is more. Not only does the Class 0.15S have a closer accuracy tolerance range, the ampere range is greater as well. Now, instead of only being accurate from the nameplate rating up to the rating factor, the CT must be accurate all the way down to 5% of the nameplate value.

We can use a Class 0.15S, 600:5 CT with rating factor of 4 to create another example. In the previous example the CT was accurate to within 0.3% from 600 amps all the way to 1200 amps. From 60 amps to 600 amps the CT was accurate to 0.6%. And below 60 amps there was no guaranteed accuracy. Now with the Class 0.15S 600:5 CT the accuracy is guaranteed from 5% of the nameplate value all the way to the rating factor. So, from 30 amps all the way to 1200 amps the CT is 0.15% accurate. What a difference. This offers a very big advantage to utilities.


A high accuracy CT can be a great solution for any utility that is looking to increase their revenue. Manufacturers like Peak Demand have high accuracy solutions available such as their Alta Series™ of High Accuracy 600V Metering Current Transformers line. The next time you are in the market for CT’s think about using high accuracy CT’s instead of the standard Class 0.3 CT’s you have been using all these years.

Socket Type Meters

Socket type meters, also known as S base meters, are the most common electric meters out there today. What are the characteristics of a socket type meter? Where can they be used? What types of socket type meters are there?

What are the characteristics of a socket type meter?

Socket type meters are characterized most notably by the blades on the back of the meter. The meter baseplate holds all of the metering components. It has blades that come out of the the back of it. These blades plug into a meter socket. Hence the name socket type meter. What must be noted is the fact that the number of blades on the back of the meter varies based on the type of meter it is. This means that there are different meter sockets as well to accommodate the different types of meters.

Socket type meters are easy to install and remove. They just “plug in,” so to speak, just like plugging a cord into a receptacle. Because socket type meters can be plugged in, this means that they can make and break the load. Or, in easier terms, they can be used to turn the power on or off simply by pulling and reinstalling the meter.

Since socket type meters are so easy to install and remove they make it easy to perform maintenance. Many utilities have testing programs where all of the meters are changed-out on a cyclical basis to perform testing.

A socket type meter is usually denoted with an “S” after the form number. For example, a form 2s meter is a socket type meter because of the “S”.

Where can socket type meters be used?

They can be used in all sorts of situations. They can be used to meter residential, commercial and industrial customer. In fact, most homes, at least in the U.S. are utilizing socket type meters today. These types of meters are the go to meter. Socket type meters are also often used as sub meters. They are cheap and easy to install which is what makes them so popular.

What types of socket type meters are there?

The short answer is all of them. There are form 2s meters all the way to form 9s meters with every thing in between. This allows the socket type meter to be used to meter every type of service out there. These meters are also often times fitted with demand registers to allow them to meter demand. And with the electronic registers, these meters are now more capable than ever.

All about A Base Meters

A base meter

A base meters are one type of meter that has been used for many years. What are the typical characteristics of an A base meter? What are A base meters used for? How many different types of A base meters are there?


What are the typical characteristics of an A base meter?

Older A base meters typically had a baseplate that was flat on the back. This held all of the components of the meter and gave them a base to mount to. The base was flat because the meter was mounted to the wall inside a meter base enclosure. The older A base meters were characterized by a rectangular bottom where the terminals were and a rounded top. This is also where the globe and disc assembly were mounted.

The connections to an A base meter are on the bottom. This is also where the power is brought in. It is also where the power is sent to the customer in the case of a self-contained meter. These meters can be used, depending on the type of meter it is, with single phase or three phase power. A base meters are also used in transformer rated installations as well. In this case they are used with CTs and PTs.

What are A base meters used for?

A base meters are used for metering residential, commercial and industrial customers. Although they are not as widely used as they once were, A base meters are still in use today. There are also even models that are available with AMR and AMI modules installed. This allows easier reading and communications than were once possible. When used with most residential customers an A base meter will normally have four terminals. Two of the terminals are line in terminals and the other two are line out terminals.

So, to figure out which are which you can do a simple test with a voltmeter. Note that this only works if the meter is energized and the power is on to the service. To figure out which terminals are which check the voltage between each terminal. So, start with the far left terminal and check it against the one beside it. If you get a voltage then those two are different phases. If you get zero then those two are the same phase.

A base meters are also used for commercial and industrial customers. However, in this capacity they are normally used as transformer rated meters. If this is the case they will normally be enclosed in a large meter base with a glass window on them so the meter can be read without opening the meter base.

How many different types of A base meters are there?

Well, this can be sort of a loaded question. The way that I look at this question is how many different service types can be measured by an A base meter. And the answer to that is, all of them. There are A base meters that can meter the entire scale of service types. Whether it be 120/240v, 240v delta, 120/208v etc. So, there are just as many meter types in the A base world as there are in the S base world. This means that for whatever need you may have an A base will cover you.


A base meters were once a mainstay in the electric meterman’s arsenal.

They are not used nearly as widely as they once were but they can still be a viable option for those older installations where an upgrade may be difficult or too expensive. Furthermore, A base meters are characterized by flat baseplates and terminals on the bottom. They are also used in many different types of installations. This also means that there are many different types of A base meters still out there in use today.

Primary Metering vs Secondary Metering

Primary metering and secondary metering are two different ways of metering the usage of customers. Though the way they are installed differs, there are some similarities as well. There are also reasons why you choose primary metering over secondary metering and vice versa.

What is the Difference Between Primary Metering and Secondary Metering?

The biggest difference between primary metering and secondary metering is voltage. In primary metering, the metering is installed in the high voltage lines. Many times when referring to primary metering we are talking about distribution lines. Some common voltages for distributions lines are 12,470v and 24 kv.

Since primary metering installs its equipment on the primary, the metering equipment is rated for this higher voltage. This means that the instrument transformers, CTs and PTs, are bigger than what you would find in a secondary metering installation. Primary metering installations are typically found in three places. They are found overhead, on a pole, underground, in an enclosure, and they are found in substations.

Whether on a pole, in an enclosure or in a substation, a primary metering installation uses basically the same things. Depending on the type of service, from one to three CT’s and PTs are used.

In secondary metering installations the voltage is lower than in primary installations. Secondary metering is installed on the secondary outputs of both overhead and underground transformers. It can also be installed in CT cabinets or at the riser of an overhead installation.

Depending on the utility PTs may be optional on voltages over 120v. Other utilities require PTs on anything over 240v. This is my recommendation

What are the Similarities Between Primary Metering and Secondary Metering?

Actually, they are quite similar. The secondary sides of the CTs and PTs wire the same. They are both marked with H1 H2 and X1 X2. This lets you know where to put your wires. Believe it or not, you actually use the same meter form numbers for both. Obviously this depends on the service being metered of course. If you have a single phase tap line that you want to meter with primary metering you have one CT and one PT. You can meter this with a form 3s meter. Just like if you were to have a two wire secondary service. You can use a form 3s meter.

The meter multipliers are calculated the same way. Use the CT ratio times the PT ratio and you have your multiplier.

Why Choose Primary Metering Over Secondary Metering?

This is best described with an example. Lets say that you own an apartment complex and the utilities are included with the rent. The tenants do not pay electric bills to the power company. Instead of having an hundred power bills in the mail every month you have one bill with the total usage.

The same works if you are large factory with several buildings all feeding off of the same primary. You can get one bill from just one meter. This may actually save you money as well in demand charges as well as facilities fees. Check with your utility on this though.

Why Choose Secondary Metering Over Primary Metering?

The biggest reason to choose secondary metering over primary metering is the ability to monitor the usage of each transformer. This alerts you to problems early on that can be fixed before they get too big. This can also help if you are a landlord over an apartment complex. You can make sure that everyone is paying their fair share of the electricity by having them pay their own bills.

What is a CT Meter?

A CT meter is simply a meter that is used in conjunction with instrument transformers known as current transformers. These are also known as CTs. In electrical metering, meters are divided into two types. There are self-contained meters. In addition there are transformer-rated meters. Transformer-rated meters are also known as CT meters.

What are the characteristics of a CT meter?

The characteristics of a CT meter include its ratings. CT meters now are generally rated at 20 amps. This means that the current coils of the meter are capable of handling 20 amps. You may think that this is low. But, remember that CT meters are used with CTs. Also remember that CTs have outputs determined by their ratios. They are rated with an output on the secondary side of 5 amps. If you remember, when using the rating factor of a CT it is possible for the CT to put out 20 amps.

CT meters also have voltage ratings. Many of the meters now are multi-range. This means that the meter can sense the incoming voltage and adjust its calculations based on the incoming voltage. Most meters now show the voltage on the display. Before digital meters, one had to be careful to make sure that the meter with the correct voltage rating was chosen.

What types of CT meters are there?

When talking about meter types what we are really referring to are the meter forms. Meter form numbers are used to designate what type of meter we have. These meter form numbers help us to decide which meter to use in which installation based on Blondel’s Theorem.

The normal transformer-rated meter form numbers are as follows:

Form 3s

Form 4s

Form 5s

Form 9s

Now remember that these are the most common. There are more.

Where will you find CT meters?

CT meters are installed on services that are too large for self-contained services. This normally means services that are larger than 200 amps. Although there are now self-contained 320 amp meters as well as 400 amp bolt in meters. CT meters are also used whenever PTs, potential transformers, are used to step down the voltage.

Large residences, commercial and industrial buildings, hospitals and schools are all examples of where you will find a CT meter installed.

Prepaid Metering

Prepaid metering is a way that both customers and utilities can benefit from the technological advances in metering that have been made in recent years. When it comes to paying for electricity it seems that the electric industry has fallen behind the rest of the retail world. Electric utilities allow customers to use their service and then at the end of the month calculate how much each customer used and then sends them a bill. This has worked well almost since the first electric bills were sent out. However, with post-pay when customers cannot afford to pay their bills they end up working out arrangements with the utility to pay at a later date. Also, some customers decide that they need to move and they do not think that they need to pay their final bills.

If only there were a way to change some of this. But there is. Prepaid metering is a way that utilities can collect the money from their services up front.

Prepaid Metering Is Good For Customers

There are several advantages that prepaid metering has to the traditional way of billing. One being that payments are collected before the customer uses the power. Just like a prepaid phone service, when the purchased time runs out, the service stops. With smart meters now including remote disconnect devices the utility can monitor the usage from the office. This allows the utility to turn the power off to customers when their purchased kwh time runs out.

Some people will cry foul here and say that it is unfair to the customer to be turned off without notice. But, the companies who offer this service provide customers with text an email alerts notifying them that they need to pay or be turned off. Many of these services offer the ability to pay from the customer’s smartphone.

In addition to being able to pay their bills from their smartphones, customer can purchase blocks of power. Customers can purchase what they can afford at the time to keep the lights on. This is beneficial to many customers who may not have the money to pay a $300 light bill at the end of the month. They may only have $50 to get them through the next few days. This ensures that they do not lose service.

Customers also have the added benefit of an online portal where they can monitor their usage. They can keep up to date with the amount of power that they are using as well as the amount of power they have left. Many studies show that customers who are on prepaid rates are more conservative with their energy usage.

Prepaid Metering Is Good For The Utility

Prepaid metering allows the utility to reduce its bad debt expense. The bad debt is debt that is written off because it will never be collected. This can be due to customers leaving without paying or customers who cannot afford to pay and change the name on the account. What happens is the utility ends up being a lender of sorts. When a customer does not pay the utility often gives them a grace period. All the while the customer is using more and more power. Their bill is getting higher and higher.

The utility eliminates some of its bad debt by collecting up front. If the customer decides to leave the utility reimburses, depending on the rate, the customer. This can be good for utilities who have meters in high turnover areas such as college towns, and apartment complexes.

One way to implement this would be to offer it on a voluntary basis. This is where customers sign up voluntarily. Another way is to start with new customers. Still yet, using credit checks is another.


Prepaid metering is not for everyone. But there are instances in which it is perfect for some. Utilities should examine whether it is beneficial to both the bottom line and the customer. Customers should view prepaid metering with an open mind and look at the potential benefits it offers them.

Time of Use

Time of use is a metering concept based around changing your usage behavior to not only lower your costs, but the costs of the utility as well. What is time of use? How can you take advantage and benefit from time of use? How does the utility benefit from time of use? These are three important questions that surround the time of use concept.

What is time of use?

Time of use is actually a very simple concept. Utilities use on peak periods and off peak periods. On peak periods are those periods during which the utility normally hits their peak. This is defined as a time period. For instance, the on peak period could be from 2pm – 5pm, Monday – Friday. In this example, the off peak periods would be everything outside 2pm – 5pm, Monday – Friday. Or, the periods of time in which the utility does not peak.

These time periods are typically have names with letters such as, period A or B. The electric meters are programmed with these time periods. Typically these meters have more than one register reading that is displayed. The readings that are displayed are for the different time periods.

In a time of use rate, on peak and off peak prices are different. On peak prices are more expensive than off peak prices. This is to encourage businesses and even some individuals to change their usage during these times. Which leads to the next point.

How can you take advantage and benefit from Time of Use?

To take advantage of time of use and reap all of the benefits you need to do a study of your usage. Some utilities will provide you with this service free of charge. They will install a load profile meter (often called a load survey meter). After a few months you can view the data. The data lets you know what times during the day you use the most power. Armed with this information you can make decisions about the available time of use rates offered by your utility.

It may be that you can come in an hour earlier to avoid hitting that peak. Or maybe completing some of your processes in the morning instead of the afternoon. The data lets you know.

Time of use offers a discount during off peak times. This is where the big advantage lies. Compare the prices of on peak versus off peak for the rates at your utility. You can save big. But beware, once your are on a time of use rate usage during the on peak time are higher.

How does the Utility benefit from Time of Use?

The utility benefits by being able to shift some load to off peak times. Looking at the utility’s consumption on a line graph shows when they peak. The normal line graph has peaks and valleys. They too are billed on the peak. Or if they generate their own power when the peaks are high they have to bump up their generation. Ideally, looking at a line graph, a utility wants their line to be straight. This means that the generation is constant. Moving some customers from on peak periods to off peak periods is one way of achieving this. The utility benefits from the lower cost of generation or price and passes that on to the customer.

In conclusion, time of use is a rate structure that is comprised of on peak and off peak time periods. It can be a great way for customers to lower their bill by shifting some of their normal routines. Utilities benefit by being able to shift some of their on peak load to off peak times thus reducing their overall demand costs as well.