External Solar Disconnect requirements for remote buildings.

[Frank.B.Smith]

Greetings again,

My contractor was out today to have me sign the contract for the 19 additional solar panels for my Garage. He mentioned that normally he would install an external disconnect on the outside of the garage. He is going to check with the inspector to see if we can do without it.

I will need to do some more research, but I thought the external disconnect was a Utility requirement and NOT a NFPA requirement. The local Utility, BGE, only requires one external disconnect at the Utility entrance to my house. The house and garage are on different streets so the wire leaves from the rear of the house and enters the rear of the garage. The disconnect would most logically be on the rear of the garage and this location makes it unlikely to be seen by the responding fire crews since they would approach from the front of the garage. If the disconnect was located on the front of the garage I fear the local hoodlums (children) would constantly turn it off for fun.

So Is there even a requirement for an external disconnect at each building that has solar. If so which Article is this specified in? Since the detached garage is not also a residence I do not believe an external disconnect is required for fire code. Fire crews seldom risk their lives to save cars in a garage.

Frank

 

[Carultch]

Greetings again,

My contractor was out today to have me sign the contract for the 19 additional solar panels for my Garage. He mentioned that normally he would install an external disconnect on the outside of the garage. He is going to check with the inspector to see if we can do without it.

I will need to do some more research, but I thought the external disconnect was a Utility requirement and NOT a NFPA requirement. The local Utility, BGE, only requires one external disconnect at the Utility entrance to my house. The house and garage are on different streets so the wire leaves from the rear of the house and enters the rear of the garage. The disconnect would most logically be on the rear of the garage and this location makes it unlikely to be seen by the responding fire crews since they would approach from the front of the garage. If the disconnect was located on the front of the garage I fear the local hoodlums (children) would constantly turn it off for fun.

So Is there even a requirement for an external disconnect at each building that has solar. If so which Article is this specified in? Since the detached garage is not also a residence I do not believe an external disconnect is required for fire code. Fire crews seldom risk their lives to save cars in a garage.

Frank

Utility required disconnects generally have the location requirement (if any) of being located nearest other utility equipment, such as meters. It depends on the utility. Some say it can be anywhere, as long as it is outside. Some put you in a Catch 22, by saying it needs to be within 10 ft and within sight of the meter, when the existing meter is inside. It is OK to lock it in the ON-position. The utility will use bolt cutters and attach their own lock, in the rare event that they ever need to use it.


Does NEC2014 apply? There is 690.12, that now requires rapid shutdown. But it is unclear where it needs to be initiated, and the people who know the history of this rule say that this was not an oversight. This was intentional so installers and AHJ's could work together to determine the best location.

I've had arguments about where it needs to be, when there are multiple buildings involved. One statement is, "well you can't put it on your neighbor's house", exaggerating to make the point that you couldn't put it on a separate building than the building that hosts the array. Such as an array is on a detached barn, interconnecting in the main house. The logic implies that it would be insufficient to have it on the main house. Again, that is complete speculation, as there are no objective guidelines where the rapid shutdown initiation needs to be.

 

[GoldDigger]

If the primary goal is to protect fire fighters working on the building, then if you think that the barn could ever catch fire you would need to have one Rapid Shutdown engine which can be triggered locally at both the barn and the house.
If you have a free standing ground mounted array, then it, or the pieces of it, would be structures but not buildings with fire fighters trying to ventilate the roof or chop holes in walls. In that case a trigger switch at the building housing the inverter (if any) would be the logical location. And at that point it makes sense to put it near the service disconnect (if outside) rather than where the DC enters the building.
JMO.

 

[jaggedben]

For the PV system the NEC requires a readily accessible (which is not the same as external) disconnect. See 705.22. This can be anywhere on the property and your utility required switch at the house already counts. I'd say about half the jurisdictions I work in allow a circuit breaker in a panel to qualify as that disconnect, and the other half require a separate safety switch.

Now because your system is on the garage you should look at Article 225, especially 225.30 thru 225.34. You should have a disconnecting means for any circuit running on or through that structure. That's what your electrician would be talking about. The PV system is allowed to be on a separate circuit from the other power in the garage (225.30(A(5))).

We're talking entirely about AC disconnects here, because I remember you mentioned micro-inverters in the other thread.