Jan 24, 2020 · The wording seems to apply to the individual device, so we put an ERMS switch on each breaker or each piece of equipment which then applies the switch to each breaker in the …

Mar 3, 2021 · The way I interpret 2017 NEC: 240.87 is that ALL breakers capable of being set to 1200A or greater require an ERMS switch. Which would include the 2000A gen breaker and 2- …

Jan 23, 2020 · Both the MCC Main breaker and substation feeder breaker have maintenance mode switches (ERMS switches in our case). I am trying to determine the proper location to …

Jun 13, 2018 · We're at the conclusion of an arc flash reduction project, and we're presented with a dilemma. We installed a switchboard with circuit breakers having a "maintenance" mode that …

Feb 11, 2025 · So I am installing a switchgear and I see a small dial on the gear labeled main relt switch I asked my foreman what it was and he had no idea what's the main relt switch for

Oct 7, 2021 · I have a question about arc flash maintenance switch (AMS) as per NEC 240.87 (B)(3). NEC 240.87 (B)(5) allows the use of instantaneous trip; does it mean that if the …

Jun 15, 2021 · How do others typically approach the ground fault setting for a facility main breaker when there is no ground fault on the feeders or any downstream devices? I'm looking at a …

Jan 23, 2018 · We are installing a 3000A 480/277A Service onto a building. There is a 4/0 ground ring ran around the Transformer and Ct Cabinet pad and then to the Main disconnect. We are …

Mar 3, 2021 · Hope everyone is doing well. I had a question about setting the ground fault protection for a 500 hp motor that is being protected by a 1000 amp breaker at 480V. The …

Nov 11, 2022 · Hi all, I wish to know more about when should I put LS, LSI or LSIG breakers in my designs. I've seen some guys do it with a rule of thumb, i.e: if it's an 800A breaker, then it's …