Six switch rule - Understanding 230.71

[goldstar]

I recently installed a 70 amp, 240 volt, single phase service to an open air building at a day camp. The service started with a 70 amp circuit breaker at the admin bldg. then a 50' run to the outside of the bldg. Once outside it went to an aerial run of about 100' to another out-lying bldg. where I installed a 3-pole, non-fused outdoor disconnect and a mast. From that point there was an existing 2" underground PVC conduit run of about 350' with a concrete vault in between. Once at the new open air bldg. I installed a main-lug breaker panel with 8 active circuits. The inspector tells me that I needed to install a back-fed main breaker because I have more than 6 breakers in the panel. I installed it without argument but I'm confused as to why multi-family dwellings can have a meter enclosure with mains installed for each dwelling and then main lug panels in each unit.

I'm now in the process of upgrading a service at a dwelling that was originally a 2-family and is being converted to a 3-family with a house panel (a 4 meter stack). If the mains are inside the meter enclosure do I now need main breaker panels for each dwelling (there are more than 6 breakers in each panel) ? The breaker panels will be located in a common area of the basement (about 10' away from the meter enclosure) with access to all.

Tnx.

 

[augie47]

AltHough there are a lot of similarities in this situation, from a Code standpoint you first need to distinguish between service and feeders (check the definitions), but normally once you have an overcurrent device it is no longer a service, so from your original post "starting a a 70 amp breaker" you appear to have an outside feeder and not a service so you Code reference would be in Art. 225.
That said, a lot of Art 225 references back to or is worded like Art 230. In your case, the disconnecting means required at each building would need to comply with 225.31, 32,33,36 etc. limiting you to the 6 disconnect rule.
IF we are talking aBout a single structure Art 255 would not be applicable, so on the triplex building where we are under one roof, the overcurrent means protection for your interior panels is allowed to be at the meter and when one is there the six disconnect rule does not apply to unit sub-panels (no main needed)

 

[goldstar]

Thanks Augie. Great answer and explaination.:thumbsup:

 

[GoldDigger]

I am not sure whether you or Augie first mentioned triplex, but since the run is a feeder, not a service, you need to run an EGC under current code. That is, two hots, a neutral, and an EGC. That is in addition to providing a GES at the second structure.

 

[augie47]

I am not sure whether you or Augie first mentioned triplex, but since the run is a feeder, not a service, you need to run an EGC under current code. That is, two hots, a neutral, and an EGC. That is in addition to providing a GES at the second structure.

I agree. I don't see any detail in the original post. I think I unappropriately used the "word" triplex referecning the OP's 3 familly dwelling. When I wrote it I wasn't sure of his wording and added the word building ("triplex building") to try an avoid the electrical issue. I should have reworded.
Hopefully the OP followed 250.32.

 

[goldstar]

Sorry for not mentioning this. The start of the run was in 4/3 MC cable. The aerial portion of the run was done in quad-plex and the under-ground portion was done with 3 # 3's and a # 6 THHN-II. At the pavilion end where the breaker panel was installed we had a CEE in the concrete pour bonded to the panel enclosure.

Yes, the tri-plex that Augie mentioned referred to the 3-family house installation

 

[jeff48356]

I am not sure whether you or Augie first mentioned triplex, but since the run is a feeder, not a service, you need to run an EGC under current code. That is, two hots, a neutral, and an EGC. That is in addition to providing a GES at the second structure.

What exactly is a GES? I know that EGC is equipment grounding conductor.

 

[GoldDigger]

What exactly is a GES? I know that EGC is equipment grounding conductor.

The GES is the Ground(ing) Electrode System. It consists of all of the various individual ground electrodes (and in some people's opinion the GEC (Ground Electrode Conductor) wires and bond wires that link them together).