Service Disconnect

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John Pullen

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Location
Tampa, FL
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Electrician
I am doing a small commercial meter installation to power a single appliance. The city is requesting that we install everything on the front of the pole instead of the load center on the opposite side of the meter I attached a picture to show the way we typically install.
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We have been using a back fed main breaker as our service disconnect
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One of the city guys today told me they just use a 4 circuit 2 space disconnect and mount it under the meter. I have seen the city’s older work and they use a main lug disconnect and feed their traffic cabinets that way. I was under the impression that I was not allowed to do that but when I’m looking in the code book article 230.85 mentions one- and two-family dwelling units. So I’m thinking perhaps I misunderstood. Do I not need a main breaker disconnect and am I able to just wire up main lug?
12c6d9fb99c319ca08d449695b04ff8e.jpg


This is how the older traffic cabinets are wired. Is this correct? Have I misunderstood this rule for years?


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texie said:
Either way is compliant prior to the 2020 NEC. Neither would comply with NEC 2020.
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I think both can comply with the 2020 as long as there are protective barriers on the exposed line side energized parts, and provided that the breaker used as the service disconnect is a two pole breaker.
 
wwhitney said:
So what's the 2020 code citation, what section did I miss?

Cheers, Wayne
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230.62(C) in NEC 2020. The code started moving in the direction of having having everything barriered on the line side of service equipment in the 2017 edition in 408.3. Then in 2020 it was rearranged to 230.62(C) and 230.71(B).
 
texie said:
230.62(C) in NEC 2020.
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That doesn't prohibit service conductor busbars, it just says they all have to be shielded by barriers. So if the main lugs have a barrier, and the bus is entirely blocked by that barrier and an OCPD, I don't see the violation.

Cheers, Wayne
 
wwhitney said:
That doesn't prohibit service conductor busbars, it just says they all have to be shielded by barriers. So if the main lugs have a barrier, and the bus is entirely blocked by that barrier and an OCPD, I don't see the violation.

Cheers, Wayne
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It is not compliant. A person can remove the breaker and be exposed to a live service bus bar.
 
texie said:
It is not compliant. A person can remove the breaker and be exposed to a live service bus bar.
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But removing a breaker isn't required to "service load terminations" so I don't see that as being non-compliant with 230.62(C). Perhaps a hold-down kit for the breaker is required; it's at least a good idea.

Now if the breaker were a style where you have to pull it off the bus in order to access the lugs to change the "load terminations," then I would agree with you.

Cheers, Wayne
 
wwhitney said:
But removing a breaker isn't required to "service load terminations" so I don't see that as being non-compliant with 230.62(C). Perhaps a hold-down kit for the breaker is required; it's at least a good idea.

Now if the breaker were a style where you have to pull it off the bus in order to access the lugs to change the "load terminations," then I would agree with you.

Cheers, Wayne
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Sorry Wayne, but I think you are off base here. This is not a gray area with AHJs and listing bodies. In fact this is why things were changed and rearranged in the 2020 edition and 230.71(B) was added.
 
texie said:
Sorry Wayne, but I think you are off base here. This is not a gray area with AHJs and listing bodies. In fact this is why things were changed and rearranged in the 2020 edition and 230.71(B) was added.
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Sure, 230.71(B) would prohibit using a 4 space panel with 2 service disconnect breakers in it, I agree with that. But it doesn't prohibit a 2 space panel with a single 2 space service disconnect breaker in it.

As to 230.62(C), nothing in that text regulates the nature of the line side (service side) connection of the service disconnect breaker. It just requires barriers.

For those following along:

(2020) 230.62(C) Barriers. Barriers shall be placed in service equipment such that no uninsulated, ungrounded service busbar or service terminal is exposed to inadvertent contact by persons or maintenance equipment while servicing load terminations.

Cheers, Wayne
 
To follow up, I can see the argument that with a plug-on connection on the line side of the service disconnect breaker, it's not secure enough and someone "servicing load terminations" may inadvertently disconnect it and thereby expose the service busbar. So saying that 230.62(C) would require a hold down kit for a plug-on breaker works for me.

But saying that it prohibits plug-on line side connections, and that they would have to be bolt-on, there's nothing in the text that supports that. And nothing that would distinguish between bolt-on vs plug-on with hold down kit. Obviously with all the line side parts guarded in either case.

Cheers, Wayne
 
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