NEC Service entrance question

[buzzp]

Our customer decided at the last minute to put in a transfer switch (manual-really a contactor), non service entrance rated (no overcurrent protection). They want to put it in after the service transformer and metering but before the disconnect. I have researched this and there seems to be some confusion in interpreting 230.82 and 230.94. From an engineering standpoint, the manual transfer switch is not protected since the overcurrent protection is after it. Based on this alone, makes this idea bad in my opinion. However, I believe the utility has cut-outs on the primary of their transformer.

In any case, is this configuration allowed by the NEC? Is it allowed since the transfer switch is UL listed and part of the requirement to maintain the listing is to provide OC protection?

Any help would be appreciated. Sorry if I posted in the wrong area. Thank you!

 

[7anoter4]

You have to check if the load supplied from this transfer switch meets the conditions noted
in NEC art. 230.94[for instance a fire pump protected separately according to art.695]

 

[jraef]

I believe it has to have an SUSE label on it if it's the Service Entrance, no exceptions (230.66). Some transfer switches offer that for that reason, or, you simply put it behind the SUSE device.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[buzzp]

I forgot to mention this is a 3 pole switch.
under 230.94, exception 1, it says the service switch shall be permitted to be on the supply side. yes this is a switch but it is not a service rated switch. Is this what they mean? the transfer switch won't be tied to any life safety or fire controls.

we use switchgear rated as service entrance equipment but also use the 6 disconnect rule so it's not as easy as just putting it after a 'disconnect' since each of the 6 switches are only rated 800A and our service is 3000A - same as mobile generator.

So what I am hearing is supporting my conclusion that it is not okay by NEC.

 

[dpc]

In general, this is not allowed, since the transfer switch becomes the service entrance and it is not rated or labeled as SE equipment and has no overcurrent protection. A circuit breaker type transfer switch could be used. These can be service entrance equipment - one of their advantages.

 

[buzzp]

Ok, article 240 Overcurrent protection. There could be some exceptions to this if this article applies. However, I don't think 240 applies because 240.3 Other Articles. Equipment shall be protected against overcurrent in accordance with the article in this code that covers the type of equipment specified in table 240.3" It clearly lists services in this table. Article 230. I take this to mean that article 240 does not apply to the service entrance.

Our electrician was using some sections of part II of art 240.21(B) feeder taps, to approve the configuration of non service entrance rated transfer switch. However, 240.3 says this is not applicable, correct?

If 240.21 applies to service entrances, then would 240.21(B) Feeder Taps apply? it says conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1) through (B)(5). I wrestle with the idea that my transfer switch would be a feeder - to me its a service entrance so none of 240.21(B) would apply.

Sorry to beat a dead horse but my boss won't leave this alone and I want to make sure there are no exceptions I have overlooked. This is a new company I work for and they said they have done this lots of times, even with electrical inspections.
Thanks to all for the advice.

 

[waross]

Phone the local AHJ ans ask him.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[buzzp]

I convinced them to put in service entrance rated transfer switch. I don't see any way around it given our configuration.