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Old 02-07-2008, 11:14 PM   #16
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Subpanel installation in outbuilding


Just giving him the option. This way he could just buy some triplex and forget about the conduit. Them he could also forget about the separation of the grounds and neutrals. Just like to KISS (Keep It Simple Stupid). Not any attempt at being derogatory towards anyone, I just like the saying and it seems to work for me since I'm no Einstein.

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Old 02-08-2008, 12:09 AM   #17
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Subpanel installation in outbuilding


Article 225 provides the installation requirements for outside branch circuits and feeders that run on (or between) structures, buildings or poles. Branch circuits would generally be on a building in most cases coming from a panel in the building or on the outside of the building or there is an exception allowing one branch circuit between buildings. Feeders between buildings whether they originate inside or outside or terminate inside or outside require a disconnect at the detached building at the nearest point of entrance of the feeder conductors to the detached building and readily accessible.

Where you will find controversy is whether or not the 6 handle rule is allowed as the required disconnect at the building. I assume your inspector is allowing it but he is incorrect if he is saying the breaker in your main panel is the disconnect for the shed. He may allow no more than six throws of the hand in the 100 amp sub-panel to be the disconnect but not the ocpd of the feeder back in the main panel, this is not the detached building disconnect. Bottom line is if he says it is ok then he is satisfied and you can move on. You will get all kinds of argument over this this section of code. A main lug only panel in most residential settings is only allowed if it is installed in the same building as your main panel or properly called the service equipment. The disconnects for power to multiple panels in a single building must be grouped together in a single location and in this case this will satisfy code. This is because your main breaker will kill all power to that single building including the sub-panel that is also located in that building.. However for a detached structure being powered from a feeder originating from a separate building where the service equipment is located cannot have its disconnect located in the other building it must be located at the structure being served by the feeder. SEE NEC 225.31 and 225.32

As Chris75 correctly pointed out the 40 amp breaker in the main panel is the ocpd for the feeder but it is not the required disconnect for the shed. You must have a single handle 60 amp disconnect or larger at the shed IMO. However your inspector says otherwise but I believe he is using the six handle rule for your sub-panel in the shed not the 40 amp ocpd in the main panel. This is where I disagree with the inspector. However this rule is commonly used and there are thousands of installations like yours is going to be. I'm simply saying that because your shed sub panel is not a power panel and is a lighting and appliance branch circuit panel with 10% of its breakers supplying lights and appliances the six handle rule does not apply and the structure requires a single handle disconnect or a main breaker or back fed breaker in the sub-panel rated 60 amps or more.
Remember a panelboard is allowable as service equipment (which is the requirement of the disconnecting means from Art. 225.36) if less than 6 throws of the hand (handles) are installed and it is not a lighting and appliance branch circuit panel board. Your sub panel is a lighting and appliance branch circuit panel because it has more than 10% of those six throws using lights and appliances. This makes it not suitable for service equipment under the 6 handle rule so some form of main disconnect that is service rated is required at the shed that has one handle... not six or less.
I have recently come to believe this a commonly misapplied section of code allowing the six handle rule at a detached structure using a sub panel that meets the definition of a L&A&BCP.

EDIT: My explanation for the 6 handle rule is paraphrased in my words from the source that changed my opinion located here.....

http://forums.mikeholt.com/showpost....3&postcount=12

Last edited by Stubbie; 02-09-2008 at 12:13 PM.
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Old 02-08-2008, 10:39 PM   #18
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Subpanel installation in outbuilding


Article 225 is mostly directed at non-residential premises. The 60 A rule is for the size of the disconnect, not the circuit.

You must run four wires, 2 Hot, 1 Neutral, and 1 Ground. You can get away with running only three, but this is NOT a good way of doing it, as some neutral current must return through the earth. USE FOUR WIRES.

Having said that, you are required to install a grounding electrode (i.e. a ground rod) at your out building and connect it to the ground bar in your subpanel, which you can purchase at the same place you bought the panel. If you have metal water piping in your building, you must bond that to the ground in the panel. Same goes for concrete rebar and the metal structure if you have one. And grounds and neutrals must be kept separate.

Also, given the distance, you might consider increasing the size of the conductors to compensate for voltage drop.

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Old 03-16-2008, 02:43 PM   #19
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Subpanel installation in outbuilding


I am installing similar out building circuit.

40 amp 2 pole breaker in 200 amp house sub panel with seperated neutral/ground

the main ground bonding jumper is at meterbase/diconnect/elcetrode location at driveway

#2 wire to 100 amp sub in pump house (#2 used for voltage drop)
4 wires to this panel with ground and neutral seperated at pump house subpanel as well

100 amp Sub panel in pump house to have backfed 60 amp main breaker/disconect
2- 2 pole breakers -1 for each pump (well-20amp)&(pressure pump-15 amp)
1- 1 pole breaker - for general lighting/receptacle circuit 20 amp
(demand @ 25 amps total)
Second grounding electrode at pump house.

Does this sound to code

Last edited by mrdave; 03-16-2008 at 02:54 PM.
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Old 03-16-2008, 03:19 PM   #20
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Subpanel installation in outbuilding


Quote:
Sub panel in pump house to have backfed 60 amp main breaker
The main breaker need to be secured via screw to the panel. It will function but not pass close inspection.

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