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.
Conclusion
A base meters were once a mainstay in the electric meterman’s arsenal.
They are not used nearly as widely as they once were since socket type meters have taken over, 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.