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· A "Handy Husband"
15,070 Posts
Discussion Starter · #1 ·
I am in the process of installing a 60 amp sub panel in my attached garage to alleviate my overcrowded 200 amp main panel. I will be transfering my water heater, irrigation pump and garage circuits into the new panel.

As phase 2, I am replacing the wiring to my 2 outbuildings, a garage/workshop and the pump house for my potable water pump. The existing wiring to each building is a 20 amp, 120 volt circuit using 12-2 UF cable. It is buried about 3-6" deep and has stuck up out of the ground in spots (not good). My plan is to come off my new garage panel with 1.25" SCH40 PVC (I have a lot of it) to the garage/workshop (about 60 feet). I plan pulling 4 #`12 THWN to create a 20amp MWBC for that building.

I would also like to pull in 3 more #12 THWN to the garage, switch to 12-2 UF cable to the other side of the building and go buried to the pump house(about 15 feet). I would use this as a 240 volt circuit for the new pump I am installing. No 120 volt required at the pump house. This will save me a considerable amount of digging.

The 240 circuit will have no termination in the garage, other than the splice from the THWN to the UF. In fact I was planning a separate box just for the 240 volt splice to keep it away from the 120 volt MWBC.

Question is: will I be violating the no more than 1 circuit to a building without a sub panel rule by having the 240 circuit for the pump go thru the garage?

I have considered another small sub panel in the garage/workshop but really do not need the capacity.

· Registered
6,042 Posts
Good question. I am not certain as you will not be feeding the structure twice, just passing through. Lets here from some of the other electricians on this.
If this were my project, I would use the conduit to feed a sub panel in the first structure. From that sub panel I would feed the remaining areas requiring power. Heres the article.

II. More Than One Building or Other Structure
225.30 Number of Supplies. Where more than one building
or other structure is on the same property and under
single management, each additional building or other structure
that is served by a branch circuit or feeder on the load
side of the service disconnecting means shall be supplied
by only one feeder or branch circuit unless permitted in
225.30(A) through (E). For the purpose of this section, a
multiwire branch circuit shall be considered a single circuit.
(A) Special Conditions. Additional feeders or branch circuits
shall be permitted to supply the following:
(1) Fire pumps
(2) Emergency systems
(3) Legally required standby systems
(4) Optional standby systems
(5) Parallel power production systems
(6) Systems designed for connection to multiple sources of
supply for the purpose of enhanced reliability

· Master Electrician
1,453 Posts
Scratching head too. I suppose 225.31 & 225.32 would apply also?

225.31 Disconnecting Means. Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.

225.32 Location. The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. (complete section not quoted here)

· Licensed Pro
1,571 Posts
Since this second circuit passes through the building, it will require a disconnect in that first building. That, IMHO, would constitute a second circuit and violate 225.30. I would run a small sub with #8 at the first detached building and feed the pump from there. That would also allow for more circuits at the shop if ever needed.

· A "Handy Husband"
15,070 Posts
Discussion Starter · #5 ·
Thanks to all that replied. It appears my plan will not fly. I think I will follow your collective advise and install a small 120/240, 30 or 40 amp sub in the workshop and feed the pump house from the sub. Looks like I can add a disconnect breaker to a 8-12 space main lug panel and get a way pretty cheaply. I am aware that I will have to add a separate ground par, a breaker hold down kit and ground rods.
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