Does anyone still bring 480 volt into the socket on transformer rated metering? If you do I would recommend changing that process. It eliminates a flash hazard inside those sockets and don’t believe many test switches are rated for 277 L-N, most only say 120 I believe.
How you want to do the step down of voltage is up to you. There are VT packs available by companies such as Ritz or two sockets one meter. Those are good viable solutions or you can also use old standard VTs. Minnesota Power we still use standard 500 VA core VTs to accomplish this. We require on services that have VTs that a separate VT compartment is installed. The VTs can not be installed inside the CT cabinet where the current carrying bus/wire is located. This keeps us from having to be exposed to high energy arc flash hazards when doing high side voltage checks. Thus far this hasn’t been much push back from electricians on this standard. They tend to be fairly understanding of the arc flash issues.
Jason – We just ordered some Flash Sentry Sockets from Brooks UP – We have been using the TSTM sockets/VT packs and like them. The difference with these are the 480V is all in a separate compartment in the socket – completely eliminating any 480 volts in the meter socket/test switch socket.
I wish we all could have the same concept of safety when it comes to 480V and industry wide – require these sockets in new installations. Safety should always trump price when it comes to metering!!
I cringe when I hear someone say they just use Test Switches when it comes to metering 480V – That’s not safety and when you test that service – you are still hooking up to 480V in the test switch – Use VT packs – Could save a life or your face!!
The Upper Midwest Metering Association serves the upper midwest states of Minnesota, Iowa, Wisconsin, South Dakota, and North Dakota. We provide connections for members, utilities, meter schools, and vendors in our bi-annual meetings and continuous dialog throughout the year.