“Self-contained meter pan” vs “meter pan” ??

[rrc14]

Anyone know what the distinction is between a self-contained meter pan and a meter pan. I’ve been going over a utility customer service utility manual and the “self-contained meter pan” is called out frequently. Don’t know what is different between the two pans.

 

[david luchini]

A "self contained" meter pan would not involve the use of instrument transformers.

 

[Carultch]

Anyone know what the distinction is between a self-contained meter pan and a meter pan. I’ve been going over a utility customer service utility manual and the “self-contained meter pan” is called out frequently. Don’t know what is different between the two pans.

Self-contained meters are usually what you see on circuits that are 400A and less. All the sensing equipment is inside the meter globe. The meter socket contains simple terminals for landing the wire, and jaws for mating with the meter globe's plugs. You'll see meter sockets like this, up to 320A meter sockets that get installed with a 400A breaker protecting the circuit. The 320A metering ampacity is based on the rated continuous load, which is why it is only 80% the corresponding breaker.

The counterpart to self-contained metering, is instrument metering. You see this on circuits either over 400A, over 600V, or both. This means that there are current transformers external to the meter globe, which re-scale the measured current into a lower value that the instrument-rated meter globe can process. And possibly potential transformers to do the same with voltage, if applicable. You'd likely have the CT cabinet for landing the main circuit's wiring and installing the metering CT's. A separate transformer-rated meter socket enclosure would host the meter globe, and have its inputs wired to the secondaries of the CT's in the adjacent CT cabinet. If it is the service metering, both of these enclosures might be closed with the meter seal. You might also see this equipment as sections built-in as part of a switchboard.