Is it legal to have a 20A feeder to 3 circuits in a shed?

G

gene6

Senior Member
Location
NY
Occupation
Electrician
Hello gang, I have a customer that ran a 12/3 UF to a shed, I typically run a minimum of 10/3 but this is now installed and buried.
I realize I could install a 2 pole switch but I was planning on installing a 4 spot main lug panel with 3 breakers 20,20 and 15, so lights and equipment are not on one GFCI breaker. Is it legal to have a 20A feeder to 3 circuits? The main breaker at the building is a 2-pole 20. And if so can I run a #12 to the ground rods?
Thank you
 
You would have a single feeder to the panel. Since it's a separate structure you'll need a GES.
 
Yeah a single 12/3 feeder, I just grabbed my code book and found the section I was worried about its 225.39, since I'll have more than two circuits do I need to have a 60A feeder or a 60A main?
I always get confused about article 225
Thanks
 
225.39 is for the size of the disconnecting means not the feeder. This is another code section that needs work. Why would you need a 60 amp disconnect for a 20 amp feeder? :rolleyes:
 
infinity said:
225.39 is for the size of the disconnecting means not the feeder. This is another code section that needs work. Why would you need a 60 amp disconnect for a 20 amp feeder? :rolleyes:
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I was figuring the feeder disconnect is at the main building (the source of the feeder).
I am planning on having a main lug panel in the shed with 3 mains, 20,20 and a 15 that add up to 45.
 
Why add a panel? If you are not upsizing the conductor or the feed breaker, you will still be limited to a total of 20A. Adding more breakers at the shed won't increase you available current, just make you chase inside every time your total loads exceed 20A, No different than what you have now.
 
Fred B said:
Why add a panel? If you are not upsizing the conductor or the feed breaker, you will still be limited to a total of 20A. Adding more breakers at the shed won't increase you available current, just make you chase inside every time your total loads exceed 20A, No different than what you have now.
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Still has to be able to shut them off at the building. I'd use a two pole switch for that and not worry about 3 ckts.
 
Fred B said:
Why add a panel? If you are not upsizing the conductor or the feed breaker, you will still be limited to a total of 20A. Adding more breakers at the shed won't increase you available current, just make you chase inside every time your total loads exceed 20A, No different than what you have now.
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Well they would have to get access to the main building if the feeder main tripped and that might be an off hours type of use but good idea Ill clarify thats what they want.
 
gene6 said:
Well they would have to get access to the main building if the feeder main tripped and that might be an off hours type of use but good idea Ill clarify thats what they want.
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There's no guarantee that a smaller breaker will trip before a larger one.
 
LarryFine said:
A: That's not how you add them.
B: That's not what the numbers add to.
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Haha thanks Larry duh 55, already too much time in the sun today.
I am looking at the 2nd paragraph of 225.39
Where the branch circuit or feeder disconnecting means
consists of more than one switch or circuit breaker, as permitted
by 225.33, combining the ratings of all the switches or circuit
breakers for determining the rating of the disconnecting means
shall be permitted. In no case shall the rating be lower than speci-
fied in 225.39(A), (B), (C), or (D).
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and D
(D) All Others. For all other installations, the feeder or branch-
circuit disconnecting means shall have a rating of not less than
60 amperes
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Again, the disconnecting mean does not mean the feeder capacity.

Still, with a 3-wire feeder you would try to balance the loads as much as you can, so you would place the more highly-loaded 20a circuit on one line, and the other 20a and the 15a circuits on the other.

Thus, the highest load you might place on your 20a feeder is 35a. :sneaky:
 
LarryFine said:
Again, the disconnecting mean does not mean the feeder capacity.
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Thanks again for your input, the disconnect of the feeder where is where it begins no? It starts from a 2 pole 20 in the main building. If I shut off the breaker at the end of the feeder I have not disconnected it, its still on.
 
infinity said:
You would have a single feeder to the panel. Since it's a separate structure you'll need a GES.
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Seems to me he has (1) Multiwire Branch Circuit feeding the structure (which is considered a single circuit) so no Grounding Electrode System is needed. 250.32A

His disconnecting means can be not more than 6 switches or circuit breakers in a single enclosure. 225.33a.
So he should be good with his MLO panel.

JAP>
 
jap said:
Seems to me he has (1) Multiwire Branch Circuit feeding the structure (which is considered a single circuit) so no Grounding Electrode System is needed. 250.32A

His disconnecting means can be not more than 6 switches or circuit breakers in a single enclosure. 225.33a.
So he should be good with his MLO panel.
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If there is a panel in the shed then the condcutors feeding it are a feeder not a MWBC.
 
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