NEC 230.82(5) for SPDT Manual Generator Transfer Switch

[Bjenks]

Trying to determine if I can use NEC 230.82(5) which referenced Taps can be used on the supply side of a disconnect if used for a standby power systems. I have an EC who has a bank customer who has a 800A 3 phase service and want to put a connection in ahead of it so they can manually connect a temporary generator if needed. He wanted to install a SPDT switch in that would either have the utility supply the load or the generator (the generator breaker would be isolated N-G). I said no he would have to install something upstream that has OCPD for the utility in it, create a N-G connection, run a ground to the existing service, isolated the N-G in the existing service panel. Now I am reading NEC 230.82(5) and wonder if I was wrong? Or Maybe that is referring to a tap that feeds another service rated ATS that also has a normal supply OCPD such as I would do for a fire pump?

 

[rlundsrud]

I would put it after the main disconnect and float the neutral on the generator so you can use a 2 pole transfer switch with appropriate OCP. I don't really see any advantage to putting it on the supply side of the main and I don't know if that is allowed. If you bond the generator neutral, it would require more work than using the main panel neutral bond and GEC. You would need a 3 pole transfer switch as well as a GEC to the generator. Does he want to use a manual transfer switch so he can do the load shedding manually rather than an ATS with a sub panel for the circuits that will use the standby sysyem?

 

[Bjenks]

The banks main disconnect is actually part of the switchgear for the building so you really can't put it after the main disconnect in this case. Sorry I didn't explain what type of disconnect is existing. Also this was just one example of many other situations that come my way where someone is trying to put a whole building generator on an existing service. So I am specifically focusing on applying NEC 230.82(5).

 

[GoldDigger]

Your switch, whether manual or automatic, needs to be rated for use as service equipment since it takes a POCO input without upstream OCPD.

 

[Bjenks]

Your switch, whether manual or automatic, needs to be rated for use as service equipment since it takes a POCO input without upstream OCPD.

Rabbit trail alert: Just want to address this as I have had several EC who believe they can put a non-OCPD ATS in front of an existing main OCPD breaker service electrical panel only because it is service rated. I do not believe that is true and they seem to be surprised when I tell them that. In order to use the ATS as service equipment it needs to have a main breaker in the normal supply of the ATS or something upstream (making that the SE and not the ATS). Now if we are talking about a DT non-fused switch reading 230.91/.94 and this thread it seem you can use it as the service disconnect if they are basically mounted right next to each other. http://forums.mikeholt.com/showthread.php?t=165357&page=4 I will say this was an enlightening thread