3 Reasons Why You Should Be Using PT’s

Why use PT’s? That is a good question and this post offers three reasons why you should be using PT’s in your transformer-rated services. First, let’s review what PT’s are. PT stands for potential transformer. Some people call them VT’s which stands for voltage transformer. The names can be used interchangeably. PT’s are used to step down the voltage in a transformer-rated service to a safer and more manageable level. If you want more information on PT’s then check out our page on CT’s and PT’s. That brings us to the three reasons why you should be using PT’s.


The biggest reason why you should be using PT’s in your transformer-rated services is safety. Safety is very critical for your metering personnel and lineman. So, how do PT’s increase safety? Remember that PT’s step down voltage from a higher voltage to a lower voltage. For instance, if you have a 3 wire 480v delta service you could use 4:1 PT’s to step the voltage down at the meter base to 120v. This is much safer for utility personnel to work with.

Anything above 240v should be using PT’s to increase the safety of metering personnel and lineman. This means that instead of allowing 480v 4 wire wye and 3 wire delta self-contained services you should consider using a CT cabinet with CT’s and PT’s no matter how small the service is. This can help prevent exposure to 480v.

Prevent Catastrophic Meter Failure By Using PT’s

Below you can see what happens when a self-contained 480v meter blows up. This particular service was not even

Form 12s 480v meter blows up

Form 12s 480v meter blows up

in use at the time. The building that this meter serves is vacant. This is an Itron Sentinel form 12s meter installed in a 480v 3 wire delta service. Things like this can and do happen. If however, this installation had been metered with instrument transformers and used a CT cabinet or even overhead metering this meter would probably have not blown up. It does need to be mentioned however that if something in the service caused this meter to blow up then most likely had PT’s been used, one of the PT’s would have blown as well.

I can hear what you are saying right now. Well, if the PT is going to blow to then what is the point? The point is that when a PT blows it is generally not a catastrophic failure like shown in the pictures. Sometimes when a PT goes bad it is even hard to tell from the outside that anything has happened. Yes, you will still have a PT to replace but the failure will not be catastrophic. Although not the case in the pictures, often times when a meter blows like this the meter base needs to be replaced as well. Also, when a meter fails like this it can create fires as well. Which brings us to our last reason why you should be using PT’s.

Reduce Customer Downtime By Using PT’s

When you have a meter failure like the one shown in the pictures what does that mean for your customers? That means that they are going to have some downtime while you make the necessary repairs. At a very minimum you are going to have to replace the meter. Many utilities now have policies that prevent their personnel from working on 480v services while they are still energized. This means that while any repairs are made power to your customers will remain off. This can be the case even in the event that you are using a transformer-rated service with PT’s. In the

Form 12s 480v meter failureevent of a meter failure on a self-contained service like the one shown above power will be turned off until a new meter can be set. If the meter base is burned up or if a fire is caused this can mean that an electrician will have to be hired by the customer and also that the fire department will come out and inspect as well. Sometimes this means that the customer will have to pass inspections before the service can be restored. This can be a few days sometimes. If however a PT fails, the power may only need to be off for 30 minutes while the bad PT is replaced and everyone can go on their merry way.


PT’s are an essential tool that can be used to increase the safety of utility personnel who work on metering installations. When used properly they can help prevent catastrophic failure of metering installations. On top of that when used, PT’s can reduce the downtime your customers experience by reducing the number of meter failures and by reducing the time it takes to make repairs when a failure does occur.

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.

Primary Metering vs Secondary Metering

Primary metering and secondary metering are two different ways of metering the usage of different 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 are the voltages. In primary metering, the metering is installed on the high voltage lines. Many times when referring to primary metering we are talking about distribution lines. Some common voltages for distribution 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.


Primary metering and secondary metering are both good ways to meter a customer’s service. They are two different approaches to the same problem. You can meter a large industrial customer with primary metering equipment even though they may have ten different transformers on their site. You could also meter those ten transformers with secondary meter and come out the same.

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.

Totalizing Meter Readings

Totalizing meter readings can be a very effective way to lower your demand and KWH costs. So, if you are a commercial or industrial customer and have multiple meters you may benefit from totalizing your meter readings. What is totalizing? How can you benefit from totalizing? What are the different methods of totalizing?

What is totalizing?

Totalizing, at its simplest form is nothing more than addition. You take the meter readings from all of the meters that you have and you add them together. This, in turn, gives you one meter reading. Furthermore, it is much easier many times for the customer as they only have to keep up with one bill. A more advanced definition of totalizing is that by combining your meter readings the peak demand can be effectively reduced.

To explain this we need an example. Look at the picture below. In it you see that there are three lines. In this example we have meter A, B and totalized meter C. Also note that the numbers on the bottom are hours of the day. Here we are assuming that the demand interval is hourly. Notice that meter A peaks at 3:00 PM. The peak demand for meter A is 24 KW. Notice that the peak demand for meter B is also 24 KW but it occurs at 9:00 AM. If you do not remember how demand works go over to my page on demand for a better understanding.

.totalizing chart

Now that you have seen where meters A and B peak, let’s look at the totalizing meter C. Meter C peaks at 12:00 PM with a peak of 19.5 KW. This is 4.5 KW less than both meter A and meter B. This is because the totalizer effectively averages out all of its inputs. With KWH totalizing simply adds all of the KWH readings of the meters.

How can you benefit from totalizing?

Well, using the example above I am sure that you can see that your demand is reduced. So, let’s put that into dollars. Assume that your per KW demand charge is $15.00. For each meter that you have, A and B you will pay $360 each (24 KW x 15). So, for both meters you pay $720 per month just in demand charges. In addition, if you totalize with meter C your demand charges would only be $292.50 (19.5 KW x 15). A savings of $427.50! This is huge! However, remember that this is just an example, it is exaggerated.

You also save with your KWH charges. The reason for this is that most rates are tiered. Meaning that the price changes as you use more KWH. Also, in most cases the price goes down. If meter A uses 10,000 KWH in a month and meter B uses 15,000 KWH in month then in total they use 25,000 KWH. However, if the price buckets are as follows:

  • $0.10 for the first 5,000 KWH
  • $0.08 for the next 10,000 KWH
  • $0.06 for all over 15,000 KWH

then if your meters are billed separately you will not be able to take advantage of the cheaper rate bucket. If you totalize however you will be able to take advantage and save on your KWH as well.

What are the different methods of totalizing?

There are two main methods of totalizing. Totalizing with software is the first. Using hardware, such as the meter is the second. To totalize with software the utility downloads readings from each of the meters that are to be totalized. The utility then uploads the readings to a totalizing program. This program looks at all of the readings adds them together and averages them out. Then it gives you the totalized readings.

Using hardware to totalize is a bit different. Wires are run from the meters that need to be totalized. Then to a central meter that totalizes the readings internally. The utility then reads this totalized meter to get the readings. Finally, the utility bills the customer with the totalized readings.

Final Thoughts

Although it sounds like totalizing is definitely worth it you need to be aware that your utility may charge a premium to totalize your readings. This can vary and also may not be worth it. Instead of paying facility charges for the meters that you already have, you may pay for those and the totalizer. In addition, totalizing meters are expensive.

It is best to talk with your utility to determine if you are a good candidate for totalizing.

Computers and the Meter Tech

As a meter tech a computer will be very useful in your job. Many tasks in the metering world are not possible without the use of a computer. Because of the this meter techs will need to know how to use different programs. They will also need to know how to analyze data.

Programming meters as a meter tech is an easy streamlined process. Many of the meter manufacturers have easy to use programming software. Once the program is built all you need to do is connect the probe to the meter. Then click the program and go through the prompt. Building the program can be tricky for those who do not know their way around a computer. If you need to change variables you need to know what the changes will do in the program.

Outside of programming meters, meter techs will need to be able to use Microsoft Word and Excel. Word is not used as much as Excel but is good to know. Many tasks can be completed with Excel. However, it will mostly be used to view data. At times data will also be exported to Excel. At other times data will need to be calculated in Excel. You can also use Excel as a small database for things such as test sites, or new installations. Meter techs also use Excel to view .CSV files and bill details.

One of the most important uses of the computer to the meter tech is billing system. Here the meter tech will look up the details of customer bills when talking to customers about their high bill complaints. It is important to know how to use this system and use it effectively. There are typically historical comments where other techs may have gone out before you. Also, you may find out that this is a problem customer. If that is the case you will know that you need to be on your game. This means meeting the customer with all of the facts.

In the billing system, meter techs will also assign multipliers to meters. This is very important. An incorrect multiplier in the billing system is one of the easiest mistakes to make. Especially if you have just completed a new installation. Billing systems are typically good at kicking out readings that appear to high or too low. And if a meter was just changed and the incorrect multiplier for that particular meter was put in the system it will generally get kicked out. However, with at new installation the computer has no history of that location to go on. Noticing this error could take years. Furthermore, this could be in the customer’s favor or in the favor of the utility.

In conclusion, being a meter tech is more that just going out in the field and swapping out meters. You need to have a good grasp on technology. Computers are essential to meter techs. The sooner you can master at least the basics the better.

Testing a Form 9s transformer rated installation

The form 9s meter is perhaps one of the most popular meter forms used in metering. It is a versatile meter that can be used to meter either a 120/208 three phase four wire wye service or a 277/480 three phase four wire wye service. Can the form 9s be used to meter other services? Yes but I am only going to cover these two here. When testing a form 9s transformer rated installation you will be looking at a few different things. You will check the meter, the wiring, the CT’s and/or PT’s, and the voltage as well as the transformer.

First a disclaimer. If you are not a meter tech or a qualified person then you do not need to attempt anything that is written below in regard to the form 9s. It can kill you if you do not know what you are doing.

When we check the form 9s meter in a transformer rated installation there are a couple of things that we will look at and take note of. First we want to check the meter number. I know this sounds simple but you want to make sure that you are in the right place. Now write down the readings of the meter. There should be a simple kwh reading as well as a kw reading. It is also possible that your utility uses more than these such as kva. You may also be required to download the information from the meter as well. If the meter is a solid state meter you want to make sure that there are no diagnostic codes in the meter. If there are you will need to check them and find out what the problem is.

Solid state meters have come a long way. If you do not have a piece of test equipment that is capable of showing you the vector diagram of your form 9s meter you can logon to the meter and view the vector diagram there. The vector diagram can alert you to things that you may not be able to see right away. Vector diagrams can also let you know if you have any wires crossed as well as the amplitude of the current and voltage on all three phases. Using vector diagrams you can also view all of your phase angles.

We are still talking about the meter here. If you have an electro-mechanical form 9s meter then the procedure is a little different. There is nothing to logon to. The meter may have lights for each voltage phase. If so, you want to make sure that they are all lit up. Next, you want to do what is know as an element check. You will also do this with the solid state meter but you will have to leave all of the voltage switches in as the display likely comes off of A or C phase. To do the element check you will open all of the switches with the exception of the neutral switch. Then you close the voltage switch and the current switches for the phase your will be working on. You are doing this to ensure that each element in the meter causes the disk to rotate in a forward direction. Remember that the disk rotates in a counter-clockwise rotation.

After checking the meter you will want to check the wiring of the form 9s. Give the wiring a good visual check. Look at all of the terminations that you can see and make sure that the color code is correct. If you suspect overheating and think the wire needs to be replaced do so as soon as possible. Wires that are out in the sun tend to crack after several years so you want to make note of this. If the wiring needs to be replaced make a work order to do so. Look at the wiring on the CT’s and PT’s. Does everything look good? Improper wiring is one of the biggest causes of lost revenue with a form 9s metering installation. If the wiring looks good, let’s move on to the CT’s and PT’s.

I am not going to go in depth in this post about testing the CT’s and PT’s, that is for a later date. What I want to tell you here is to visually inspect the CT’s. If you can see the nameplate then that is great. Make sure that the multiplier on the meter matches whatever the CT ratio says that it should be. After that, make sure that the multiplier on the meter is what the multiplier is in the computer system.

This is one of the other big mistakes that you will find with the form 9s. It is so easy to input a multiplier incorrectly into the system. That is why you need to check it for every transformer rated meter that you test. After you verify the CT ratio on the nameplate use test equipment to test the CT. This may be a CT burden test or an admittance test. You can also do a ratio test.

After the CT’s you will want to check the PT’s. Verify the wiring and make sure that you do have voltage on all three phases. The PT’s are so much easier than the CT’s. On the subject of PT’s we always want to check the voltage and make sure that it is the correct voltage for the service.

Next we want to check the transformer. Look at the transformer and make sure that it is not leaking oil anywhere. Also, visually inspect all of the secondary connections that you can see and make sure there is no overheating. If you have an infrared camera now is a good time to use it and check the connections for hot spots. Be very careful when working around transformers as it is possible to have the primary connections very close to the secondary. Make sure that you are wearing all of your PPE before doing any of the aforementioned work.

You will want to check the KVA of the transformer and compare it against the KW reading of the meter which is called demand. If you cannot get the power factor from the meter either because it is a mechanical meter or you do not have a way with another piece of equipment you can use 80% for the power factor.

To convert KW to KVA you will divide the KW by the power factor. This will give you KVA. Let’s do the calculation. Let’s say that you have a form 9s meter that has a KW reading of 0.8 with a multiplier of 80. First, multiply 0.8 x 80 = 64 KW. Then if you cannot get a power factor reading assume 80%. 64/.80 = 80 KVA. Now that you have the KVA check to make sure that it is in the limits of the transformer. If it is you are good. If not get with engineering to make a change.

There it is. That is how to can check a form 9s metering installation. As always, be careful and always wear your PPE.

What are test switches for?

Every now and then in the electric metering field you will run across a transformer rated metering installation that does not have a test switch. Is this a good thing or a bad thing? Most CT rated installations require that test switches be installed. These switches can be used for a few different things. To test the meter, to shunt the CT’s, to safely remove the CT rated meter from service and they can also be used to check the voltage and the amperage on the service without actually having to open an enclosure or go into a fence.

Why do certain installations not utilize test switches? The answer here would most likely be cost. The meter bases or CT rated installations that you will typically find without test switches are form 3s and form 4s meter bases. Form 3s and form 4s meters are many times found on large residences and sometimes large temporary services such as construction services or school trailers that are not thought to be in service very long. The cost of installing the test switch along with the cost of the larger meter base to hold the test switch is often times a deterrent. Also, in the case of residences one could argue that they just do not use enough power to justify putting a large meter base and test switch on the wall because the meter will be changed out when all of the form 2s meters are changed on their neighbors homes.

Installing a transformer rated service without a test switch can be a bad thing. One thing that you have to remember is that when you pull the meter in a CT rated service and you do not use a test switch is that you are opening the circuit of the secondary side of the CT. This leads to a build up of voltage on this circuit which is dangerous to metering personnel. The proper procedure without a test switch would then be to shunt the secondary side of the CT before pulling the meter.

Test switches can be used to test the meter. With different types of test equipment they can be used to test the meter in service using the load that is available at the customer’s site. This can be a good test to show exactly how the meter is metering the service under the load that is currently on the service. You can also test the meter using a phantom load while it is still in the meter base using the test switches.

Test switches are also used to test the CT’s in the service. You can use various different types of test equipment to test the CT’s. You can test the burden on the CT circuit as well as determine how many amps are on the CT circuit as well.

To remove the meter from service you need to shunt the CT. There is a switch that does this for you. Shunt the CT out and you can safely remove the meter from service. You can also use the test switches to remove all voltage from the meter as well before removing the meter from service and before installing the meter in service.

With the new regulations regarding arc-flash hazards and safety, many utilities have adopted safety policies that no longer allow their personnel to work inside energized cabinets, pad mount transformers or other enclosures if the service is too large or if the voltage is too high. This is yet another thing that the test switch can be used for. It can be used to check and make sure that the customer is getting the proper voltage. You can also check the rotation in the meter base at the test switch as well.

All in all, it is a good practice to install test switches in all of your CT rated metering installations. They will allow you to test the meter in service, test the CT’s in service as well as allow you to check voltage and rotation. Test switches also allow you to safely install and remove meters from service by isolating the blocks of the meter base from current and voltage.

The Meter Technician Profession


So you are thinking about getting into a career in the electric utility industry and you are not really sure what you want to do. There are several career paths that you could choose. A few are power lineman, or engineer, or even maintenance mechanic. What I want to persuade you to do is to think about becoming an electric meter technician.

The electric meter technician is possibly a job that you have never even heard of. In addition, you may have never given any thought to becoming one. So what does and electric meter technician do?

Well, contrary to popular belief, we do more than just read watthour meters. We are not just “meter maids” as some lineman would have you think. Electric meter technicians do read electric watthour meters. But we meter techs also do much more than that.

To be an electric meter technician one should have, or be able to develop, a strong electrical background. Furthermore, you will want to have graduated high school. In addition, if possible, have taken some college courses in electrical theory. It would be even better if you could get an associate’s degree in electrical technology. This education will be helpful in understanding how watthour meters work. It will also help in understanding how the entire electric utility works as a whole.

Electric meter technicians test watthour electric meters either in the shop with test equipment or in the field with watthour meter test equipment. They also check residential, commercial and industrial metering installations for proper wiring and metering accuracy. There are meter techs who specialize in some of these areas. Some meter technicians only deal with residential metering installations and customers. Others deal only with commercial and industrial customers. While others may only stay in the shop and test watthour meters.

The ideal electric meter technician will be able to work outside all day. Outside the meter tech will do things such as change out electric meters, check on high bill complaints, low consumption or stopped meter orders. Meter techs will also work outside installing new metering equipment on instrument rated metering applications.

The electric meter technician will also be called upon to explain billing to customers.

Many times customers do not understand their bill and the meter technician is usually the last person the customer will talk to. The customer has normally already called in and talked to someone on the phone. They were not satisfied over the phone and now want to talk with someone in person. The meter technician is that someone. Because of this the meter tech will need to have strong interpersonal skills to be able to answer the customer’s questions. In addition they will also need to be as professional as possible. You do not want to go out a customer’s residence or business dressed like a slob. That ruins your credibility right away.

Electric meter technicians will also need to be able to perform above basic tasks on the computer. Part of the job requires the meter tech to be able to program watthour meters, download information from the meters, create new programs for the meters as well as run reports out of the billing system to find out if there are any errors. You will need to have an eye for detail. Many times you will be looking for something that stands out as unusual. Being able to determine from that information if there is a problem that needs to be checked and repaired is crucial.

An ability to do algebra also comes in handy as well. Electric meter technicians also use many formulas to complete their work. If current transformers and potential transformers need to be installed you will need to know how to calculate the multiplier. Also, you will need to know how to size the current transformers to the service to be metered. Another thing that you will need to be able to do is calculate and electric bill with demand. Many times customers will not understand demand. So it will be up to you to explain it to them in a way they can understand. There will be times that you will need to explain the math to the customer so that they understand what is going on.

Being a meter technician is a highly rewarding career. Notice that I said career and not job. The electric meter technician is a specialized field and most who are in the field work until retirement. Which also means that there are not a ton of jobs available. So when you get one, keep it! Also worth noting is that it will typically take between 5-7 years to become fully proficient as a meter tech. But even then you will constantly be learning new technology.

So, with that I hope that you give the electric meter technician career a chance.

Meter Multipliers

Watthour meter multipliers are used whenever current transformers and/or voltage transformers are used in a metering circuit. The most often question that I am asked about watthour meter multipliers is how to calculate the watthour meter multiplier. It really is a simple thing to do and this article will explain.

Current Transformers and Potential Transformers

CT’s and PT’s are used to step down current and voltage in a metering circuit to a safe and measurable level. But this leaves us with a little bit of math to do to accurately calculate the number of KWH or kilowatt hours the customer has used.

To calculate the meter multiplier we need to know what the CT ratio and PT ratio are. The best way to explain this is with an example.

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Meter Multiplier Example 1

Let’s say for instance that you have a 120/208 three phase 4 wire wye service that is using 400/5 CTs.

How would you determine the watthour meter multiplier? You would simply do the math. 400/5 means 400 divided by 5 and if we do this math we come up with an answer of 80, this is our watthour meter multiplier. What if we had 600/5 CTs? 600 divided by 5 is 120, so our watthour meter multiplier is 120.

Now what if the service that we are metering is a 480v service and we are using PTs? For this example let’s assume we are metering a 480v three phase 4 wire wye service by using 400/5 CTs and 2.4/1 PTs. How do we come up with the watthour meter multiplier in this example? We would use the same method as before to find the CT ratio and do the math of 400 divided by 5 which equals 80 but we are not finished because in this example we also have PTs. Before we do the math let’s remember Ohms’s law which says that Watts = volts x amps. Let’s also remember what we are trying to figure out. We are trying to find the multiplier for the WATThour meter. So to find watts we need to multiply volts x amps. We already know the amps part of the equation equals 80 so what is the volts part? It is 2.4 because 2.4 divided by 1 is 2.4. So, we now multiply 80 x 2.4 and we come up with 192 which is our watthour meter multipler.

Meter Muliplier Example 2

Another example with PTs and CTs. Say you have a 480v three phase three wire service with 200/5 CTs and 4/1 PTs. What is the watthour meter multiplier? 200 divided by 5 equals 40. 4 divided by 1 equals 4. So, 40 x 4 = 160. Thus, the watthour meter multiplier would be 160.

When you divide out the CT ratio and PT ratio and multiply them together this is also known as the transformer factor.


So, there you have it.

To calculate watthour meter multipliers first you need to determine whether there are CTs and PTs or only CTs in the circuit. Next, divide out the ratios. And lastly, multiply the ratios to determine the watthour meter multiplier.