Hot sockets are one of the things that you will encounter if you spend anytime working in self-contained meter bases or changing meters. Here I want to discuss a few things that cause hot sockets, what kind of damage a hot socket can cause and what to look for when changing meters to spot a hot socket.
What causes Hot Sockets?
The biggest cause of hot sockets seems to be in my experience, loose connections. Loose connections can be at a couple of different places in the meter base. One of the places is where the wire attaches to the lugs. This is a notorious spot that heats up over time when it is not tightened properly. What happens is over time little micro arcs occur between the loose wire and the lug causing it to overheat. This, in turn, causes the socket terminal where the meter plugs in to overheat and voila, you have your first cause of a hot socket.
Another cause is the terminal or socket itself. In most meter bases these are spring loaded jaws that apply force to the terminals on the back of the meter. When the meter is pulled and set these jaws open and close back. Sometimes plastic boots are installed on the terminals of the meter in order to turn off a customer for non-payment or for any other reason. The more a meter is pulled in and out of these jaws the looser they become. When they get slack then tiny micro arcs happen which causes the terminal to overheat and we have another cause of a hot socket.
Yet another cause is the hot and the cold along with fluctuations in the load. As the metal in the terminals heats up and cools down due to the weather and load changes it expands and contracts. This over time can cause the jaws to loosen up and overheat.
A hot socket can also be caused where the terminal is put together or attaches to the bus bar in the meter base. Sometimes it is a screw or bolt and other times it is springloaded jaws that connect to bus bar. Either way, any slackness and you will eventually end up with a hot socket.
What kind of damage can a Hot Socket cause?
A hot socket is a very dangerous occurence. The worst thing it could cause is a house fire. You can see in the picures below that a hot socket in a meter base can lead to melted wire. It can also lead to overheated terminals on the meter itself. This causes irreversible damage to the meter to the point that the meter has to be replaced.
Especially with the newer solid state meters there seems to be a lower tolerance for overheating of the terminals in a meter base. It is also not uncommon for customers who have hot sockets to experience flickering and dimming lights.
What to look for when changing meters?
When changing meters it is imperative that before pulling out any meter a quick visual inspection is done. This includes looking at the front of the meter and visually inspecting the wiring and terminals before pulling the meter out. It is very important not to take this step for granted. When terminals get so hot that they fail they can actually weld the terminals to the socket. This along with melted blocks in the meter base can cause a serious safety issue when pulling the meter.
So, look at the back of the meter the best you can before pulling it out. Once the meter is out you need to visually inspect the meter and the meter base before installing a new one. Some of the signs of an overheated terminal on a meter are discoloration and melting of the base plate. Likewise, some of the signs of a hot socket are discoloration and melted blocks and wire.
If you find this situation do not put a meter back in. The blocks, and possibly the wire and meter will all need to be replaced. Depending on you jurisdiction, this may be up to the utility or the homeowner to repair.
Hot sockets are something that every utility deals with. Be sure to be on the lookout for the causes and effects of hot sockets to keep those meters turning. As always, like us on Facebook and invite your friends!