Manual transfer switches

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RUWired said:
230.94 Relative Location of Overcurrent Device and Other Service Equipment
The overcurrent device shall protect all circuits and devices.
Exception No. 1: The service switch shall be permitted on the supply side.

IMO the exception would not include a "transfer switch" as a service switch.
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Why not, isn't that what it does (switch to service 1, service 2, or off)? If you look at the basic block diagram in 230.1, you see the service disconnect (switch) and then the overcurrent device downstream of that. There is no definition of service switch. Service Disconnect would have been a better work, and I don't know why they didn't use that.
 
Still can't agree with your interpretation. So its Service1, Off, Feeder/Something else. It still switches out the service.
 
suemarkp said:
Still can't agree with your interpretation. So its Service1, Off, Feeder/Something else. It still switches out the service.
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Mark, I agree it would all work but, how do you get past 230.94.You would be putting an entire generator system before the main OCPD. Unless you can convince the inspector that when switch in the gen mode, the main is now part of the gen circuit, but that would make it a sds then.
Rick
 
iaov said:
Marc is right. There are lots of easier cheaper ways to do this.
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...and you two are going to keep us on pins and needles for how long, eaxactly? Or is this the so called dramatic pause before the climax?

Drum roll please.
 
frizbeedog said:
...and you two are going to keep us on pins and needles for how long, eaxactly? Or is this the so called dramatic pause before the climax?

Drum roll please.
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Sorry, didn't realize I responded to this thread, and didn't check back. I was thinking of things like the 3rd party "InterlocKit" as well as just subfeeding a small "emergency panel" with a backfed "generator breaker" in the main panel with the panel manufacturer's see-saw type interlock between the subfeed breaker and the backfed generator breaker. A service rated outdoor transfer switch certainly is a sexy way to do a generator hookup, but it's also the most expensive.
 
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RUWired said:
Mark, I agree it would all work but, how do you get past 230.94.You would be putting an entire generator system before the main OCPD. Unless you can convince the inspector that when switch in the gen mode, the main is now part of the gen circuit, but that would make it a sds then.
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I would say that if the generator is not a Service (SDS or otherwise), the generator would need overcurrent protection on its output (which most have) or you'd need an overcurrent device in front of the transfer switch but only on the side with the generator feed.

Half the switch is dealing with a Service, and that half is a service switch (so no breaker required upstream based on the exception to 230.94).

I think no matter how you argue the generator (is it a service or its just a feeder), you can make the switch work legally. You just need OCPD on the generator unless they deem it to be a Service. Main breakers are usually too large for a generator feed anyway unless you sized the generator to run the whole building at full load. So the generator is most likely going to need its own breaker anyway unless you find a transfer panel with interlocked breakers of the correct size.
 
somewhere in all this Article 225 will come into play unless that generator is on the inside of the building.

somewhere in all of this 230.91 will play some sort of role or the other
 
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