Service Disconnect as a Separate Structure

[Pierre C Belarge]

The NEC and local laws generally follow the same requirements for this topic.

The location of a service disconnect can be located outside of a building or structure, as per: (this requirement is not occupancy sensitive, it relates to all services, in all building Types)
"230.70(A)(1) Readily Accessible Location.
The service disconnecting means shall be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors."




Although the NEC does not address this, I am curious how some feel about the following question.

1. How far from the building or structure can the outside service disconnect be installed, before it would be considered a separate structure?

The separate structure issue brings about some changes in the grounding scheme(s), both in Part III of Article 250 and Section 250.32.


A second question - for thought....
2a. If one grounds the outside service disconnect to the structure water pipe/steel/CEE, etc... is it part of the building and not a separate structure??

2b. If one grounds the outside service disconnect to ground rods only and not to the structure water pipe/steel/CEE, etc..., is it not part of the building and would be considered as a separate structure?

 

[George Stolz]

The separate structure issue brings about some changes in the grounding scheme(s), both in Part III of Article 250 and Section 250.32.

I think the 2008's removal of 250.32(B)(2) for all intents and purposes, makes the grounding identical for both.

A second question - for thought....
2a. If one grounds the outside service disconnect to the structure water pipe/steel/CEE, etc... is it part of the building and not a separate structure??

2b. If one grounds the outside service disconnect to ground rods only and not to the structure water pipe/steel/CEE, etc..., is it not part of the building and would be considered as a separate structure?

I don't agree with the concept of our grounding changing the onsite interpretation of whether two chunks of something are one building. However, I don't have an answer to the questions you pose. It's all in how the AHJ views it.

 

[Buck Parrish]

Those are good questions 1 & 2.
Some thing that should be more clear in the NEC.

That is similar to how a mobile home is wired. The disco is on a pole. Then a single phase 4-wire ran to the trailer. With a main inside, too.

 

[Mvillines]

A lot of inspectors and contractors struggle with this question.

Speaking of Mobile homes, I can say that applying section 550.32 I did approved a mobile home service where the service equipment was mounted to a unistrut structure that was less than an inch from the home but not mounted to or on the mobile home. To me this met the requirement of 550.

We have a county ordinance stating that a detached garage can not be built in front of a house. So, a county resident built a detached garage in front of his house without a permit, and, of course was eventually caught by the building inspector. The building inspector required him to attach the garage to the house. This was done by fastening a painted 2X6 between the house and garage (very cheesy). Now, my question is, would a disconnect and a grounding electrode be required for the garage?

 

[Mvillines]

I don't agree with the concept of our grounding changing the onsite interpretation of whether two chunks of something are one building.

George, what are you refering to?

 

[Smart $]

Although the NEC does not address this, I am curious how some feel about the following question...

IMO, service equipment cannot serve itself nor a structure whose main purpose is support of said service equipment.

That being said, for any service equipment remote to the structure(s) served (i.e. not attached to), local earth must be bonded to the service equipment (i.e. at least one "good" ground rod, otherwise two or better).

Sorry my answer doesn't quite match your questions. Your questions make it too complex, and I like simple

 

[George Stolz]

George, what are you refering to?

If I run an EGC out to a distant building, it does not join the two buildings as one - otherwise, 250.32 would be a paradox.