225 PART II. More Than One Building Or Structure

[cohosilver]

Situation:

I have a 12/3 mutiwire branch circuit supplying lights and receptacles for metal 8'x20' conex. I want to install a disconnecting means for the conex per 225.32 because I do not think that the 225.32 Ex #1 applies to my situation. The property is not residential and documented safe switching procedures are not established and maintained. 225.36 states the building or structure disconnecting means must be identified as "suitable for use as service equipment." 225.39(A)(1) states that for a single branch circuit the disconnecting means must have a rating of not less than 15A. 230.79 reaffirms that for a single branch circuit the disconnecting means must not have a rating less than 15A. I am confused. Please clarify.

Additionally,
I would like to have the 12/3 multiwire branch circuit terminate at a 30A 2-pole NEMA 3R non-fused air-conditioner disconnect on the conex. The circuit is fed from a 2-pole 30A QO breaker at a panel in a nearby building. From the disco I would feed the lights and receptacles. At the disco I would use the small little ground bar to; bond the disconnect per 250.32(B), run a metal bonding jumper per 250.104(D)(2) to the conex, and even though it is not required per 250.32(A) Ex, I would install a #6 awg to a ground rod(s).
Does anyone see any code violations with this procedure? If so, please clarify.

Thanks in advance.

 

[iwire]

The first thing that jumps out at me is 12/3 being used with 30 amp over current protection.

 

[cohosilver]

225 PART II. More Than One Building Or Structure

This is my mistake, it is a 2-pole 20A circuit breaker that is at the building panel, not a 2-pole 30A circuit breaker.

The big question I have is whether or not I need to install a 60A service rated disconnect on the conex. If I am only taking a single circuit (2 hots/1 neutral & 1 egc) then, can I use a small inexpensive disconnect and still be code compliant?

 

[Dennis Alwon]

This is my mistake, it is a 2-pole 20A circuit breaker that is at the building panel, not a 2-pole 30A circuit breaker.

The big question I have is whether or not I need to install a 60A service rated disconnect on the conex. If I am only taking a single circuit (2 hots/1 neutral & 1 egc) then, can I use a small inexpensive disconnect and still be code compliant?

I know there have been proposals to get this change but as the code is written the disconnect for a non residential area the disco must be suitable for service equipment. Absolutely ridiculous but that is what the NEC states.

 

[iwire]

I know there have been proposals to get this change but as the code is written the disconnect for a non residential area the disco must be suitable for service equipment. Absolutely ridiculous but that is what the NEC states.

I think if we could go back and look at the reason this rule was put in was because any service rated disconnect has a means to bond the neutral to the can. Now at this point the NEC requires a EGC brought out there is no longer a need to bond the neutral to the can so this service rating requirement serves no purpose as far as I can tell.

 

[George Stolz]

...so this service rating requirement serves no purpose as far as I can tell.

And in 200 years or so, they might decide to delete it.

 

[renosteinke]

As much as I like the idea of using a $12 disconnect - personally I love the Square D QO200TR - one problem I have had is: what to do with the neutrals?

Such disconnects don't have a neutral buss, or much extra space. Nor is there even much in the way of a ground buss- two lugs only. This can make it an issue to even simply pass the 'service receptacle' circuit through when using it as an HVAC disconnect.

 

[norcal]

As much as I like the idea of using a $12 disconnect - personally I love the Square D QO200TR - one problem I have had is: what to do with the neutrals?

Such disconnects don't have a neutral buss, or much extra space. Nor is there even much in the way of a ground buss- two lugs only. This can make it an issue to even simply pass the 'service receptacle' circuit through when using it as an HVAC disconnect.

If my memory serves me correctly, those discos have a 10 AWG min wire size.