Feeder to remote building

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faresos

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I have a situation where the mains switchboard (480Y277V) feeding a distribution board which both are located in the same building. This distribution board will be feeding a transformer (480-208/120V) via non-fused disconnect switch located next to it in remote building. Does the disconnected needs to be service entrance rated?

Thanks in advance
 
Yes. If you bring power to a building, you have to have a way to turn off all power to that building. The thing that does that job has to be service rated. In your case, power comes into the building and the first thing it hits is the disconnect sitting next to the transformer. That disconnect must be service rated.
 
charlie b said:
Yes. If you bring power to a building, you have to have a way to turn off all power to that building. The thing that does that job has to be service rated. In your case, power comes into the building and the first thing it hits is the disconnect sitting next to the transformer. That disconnect must be service rated.
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Charlie,

I thought service rated equipment means the neutral will be bonded to the equipment ground bar. Since there is no neutral, why we need service rated disconnect.

Thanks again!
 
I think there must be more to the phrase "service rated" than simply the presence of an N-G bond. In any event, 225.36 says the disconnecting means has to have that rating.
 
jumper said:
How about 230.79 for a definition?
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That's not a definition, and it doesn't answer the present question. All that tells us is the minimum ampere rating. It does not tell us what the code means, when it requires a disconnect to be rated as service equipment. I suspect that phrase is defined in terms of testing laboratory standards. But I don't know what criteria a panel would have to meet, in order to get that listing.
 
And to add my two cents, the feeder disconnect will require a grounding electrode conductor to any available electrodes and the secondary of the transformer will also require the same.

Rick
 
I went back and looked up 225.36 and it does not say service rated it says suitable as service equipment. I was wrong going to 230.79 for a feeder, however 225.39 says the same basic thing. I included the definition for service equipment.

It seems to me the necessary equipment needed to connect and disconnect a load still would be based on the load calc and rated in amps.

Service rated seems to mean that it has to be rated for the whole service size of a building vs. rated for an individual load like a motor.

I am not trying to be arguementive, just trying to learn.
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You are using the word “rated” in two different, and unrelated, contexts.

I would describe the phrase “service rated” as a “conversational English” (or slang) way to say what should really be described as “suitable for use as service equipment.” In this context, the word “rated” is a modifier to the word “service,” and is a substitute for “suitable for use as.” When you say “service rated,” you are not talking about the ampere rating of the equipment. Rather, you are saying the equipment has a UL listing that declares it to be “suitable for use as service equipment.” As I mentioned earlier, I do not know what UL testing and standards apply to something that achieves that listing.

By bringing 225.39 into the discussion, you are using the word “rating” in a different context. Here, the word does describe the max number of amps you can safely push through the item. But here again, 225.39 is not defining the phrase “service equipment.” That happens in the article 100 paragraph that you quoted.

Here is the difference. Suppose I calculate that the load on a detached workshop building is 85 amps. I therefore select a panel that is rated for 100 amps, and use a 100 amp main breaker in that panel. That makes the equipment rating comply with the requirement in 225.39 that its disconnecting means must have a rating at least as high as the calculated load. But I can’t just go buy any 100 amp panel I want. In a separate requirement, specifically 225.26, I see that the disconnecting means (i.e., the main breaker in the remote building’s panel) must be suitable for use as service equipment. Thus, the panel must (1) Be rated for a load of at least 85 amps, and (2) Be service rated. Two separate uses of the same word, “rated.”

Does that help?
 
Mr Beck, Charlie if I may, all the 100(125) panels I have installed say that they are suitable as service equipment with the correct breaker installed. The definition still goes back to the ability to disconnect all ungrounded conductors and be properly sized.

In your example, I believe that yes, you can go go buy any 100 amp panel you wanted as long as it is the right type (indoor/outdoor as applicable) , has the minimum required spaces you need, and install a main breaker.

If this a UL issue, I am still confused. A non rated panel makes no sense to me.

Thank you for your time, I will study this more later.
 
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Okay I was wrong.

Okay I was wrong.

jumper said:
Mr Beck, Charlie if I may, all the 100(125) panels I have installed say that they are suitable as service equipment with the correct breaker installed. The definition still goes back to the ability to disconnect all ungrounded conductors and be properly sized.


In your example, I believe that yes, you can go go buy any 100 amp panel you wanted as long as it is the right type (indoor/outdoor as applicable) , has the minimum required spaces you need, and install a main breaker.

If this a UL issue, I am still confused. A non rated panel makes no sense to me.

Thank you for your time, I will study this more later.
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Mr Beck,

Upon further research, I see that 408.34, 35 ,and 36 and a UL listing of CTL comes into play. I am still going over the materiel. Again, thank you for your time. I still have a lot to learn.
 
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