240 to detached garage


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Old 01-16-22, 10:13 AM
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240 to detached garage

The detached garage was wired for 120 by PO (shoddily), had an issue with it, replaced entire line with new burial and placed 50% in conduit as feasible at the time.

Decided to learn welding to support my classic car and motorcycle restorations and in need of at least two 240 receptacles. Looking on the board, I see that most codes (I am in Alabama) will require a new solo 240 run to a sub panel and I can split/step down to 120 there to feed existing receptacles and lights?

I know I have at least one 240 circuit that I can use as it ran to a long since gone half water heater I am guessing was under the old cabinetry that I discovered when I remodeled the kitchen that some yokel left just taped in the wall that appears to been done many years ago...

I plan to replace the four existing florescent light fixtures to LED, there are 10 receptacles. I will need one 240 for the welder, one for a heater. The exiting 240 in the panel has a 60 AMP breaker.



 
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Old 01-16-22, 10:58 AM
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So what's your question? Need to know what size wire goes to the garage to comment on the 60A breaker.
 
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Old 01-16-22, 11:46 AM
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I am guessing that you will need a new 4 gauge 3 conductor plus 8 gauge ground feed as 120/240 volts to the garage. Any existing feed must be decommissioned (could be repurposed for a light with switches at both house and garage).


If you are sure you won't need more than 55 amps altogether in the garage (welder plus heater plus kitchenette or half bath water heater possibly plus air compressor plus electric car charging station) and the existing feed also has 3 (#6 copper) conductors plus (at least) #10 ground then you can keep the existing feed and not bury anything new.


For the #6 feed the required subpanel load analysis (sample rules at the back of the NEC code book) must come out to no more than 55 amps although the required master breaker for the garage (can be in the garage subpanel) can be 60 amps.


A wall receptacle such as that shown on the exterior wall of the garage cannot be in line with the feed from the main house but instead must be off of a branch circuit out of the garage subpanel.
 

Last edited by AllanJ; 01-16-22 at 12:22 PM.
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Old 01-16-22, 01:15 PM
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Thanks for the feedback @AllanJ

I spoke with a contractor friend of mine, he suggest converting the unused 60 AMP shown OFF, to 80 AMP, run 2/0 in conduit to 12 space sub panel. 2 pole 30 amp for 240/Welder, 2 pole 20 AMP for heater, 2 pole 20 for air compressor, 1 pole 20 AMP for outlets, 1 pole 20 for lights for 8 spaces out of 12 on panel.

I can leave the 120 run as shown, stop at that outside outlet, maybe daisy to one more weatherproof outlet.
 
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Old 01-16-22, 01:25 PM
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As long as the existing 120-volt circuit does not enter the building it can remain.

2/0 wire seems very large to me unless the garage is a long-distance away. You could likely do just fine with #2.
I would recommend going with a larger panel than a 12 space. Since this is a detached building, and you will have more than 6 circuits, you are required to have a disconnect. I suggest getting a 100 amp 20 space panel with a main breaker. That would be the best bang for the buck.
 
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Old 01-16-22, 01:57 PM
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Thanks for the feedback Tolyn Ironhand I have a 75ft run from the outside junction I posted which will be recommissioned to just two outdoor receptacles. With that said, I think a 120ft run would get me from main panel to the garage with some extra. But I do not see it being over 120 FT overall. Rainy today, I will measure tomorrow and get hard number.

So I will need a disconnect fed from the main panel, the disconnect then feeds the sub panel, correct?
 
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Old 01-16-22, 02:20 PM
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If the panel you choose to be the garage subpanel has a master breaker up top then you do not need another master disconnect at the garage for the feed coming from the house.
 
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Old 01-16-22, 02:26 PM
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#2 aluminium is good for up to 90A. Aluminum Mobile Home Feeder (MHF) is commonly used and is an assembled cable and is direct bury but it does need to be placed in conduit where above ground. The size is 2-2-2-4 or 2-2-4-6.
I was under the impression from your post you had already ran new wires to the garage.
 
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Old 01-16-22, 03:58 PM
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That outside junction box in the picture is not a weatherproof box and is WAY too small. The conduit is also too small. All of that will need to be replaced to run the new feeder.

As AllenJ posted the main breaker in the new panel counts as your disconnect as long as the panel is mounted to an outside wall and the conductors feeding the panel takes the shortest path to the panel.
 
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Old 01-16-22, 04:58 PM
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Tolyn Ironhand yes that circuit will be retained but updated properly to gray box and only for the two outside receptacles. Will pull new wire/conduit all new line from main panel to garage sub panel.
 
 

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