Electrical Supply Question

Nail Gun · Dec 9, 2018

I need to run power to my shed but I’ve discovered the cost of cable is outrageous. I’m not exactly knowledgeable on the subject so I’m looking for input.

A buddy gave me a roll of aluminum 8/3 but I’m not sure if it would be enough. Per an electrician I spoke with he suggested copper 4/3.

It’s going to be a 95’ run. I’ll be powering a 12k btu window unit. LED shoplights, 220v radial arm saw, 220V sander/grinder and a host of 110v equipment such as band saw, drill press air cleaner and handheld tools.

Will the aluminum 8/3 be enough? If not, does anyone have a lead on decently plriced copper?

highstandard40 · Dec 9, 2018

I'm not an electrician, but 8/3 aluminum will fall far short of your requirements. Aluminum can serve you well and will be cheaper but you will need a much larger size. I just ran a similar distance for a 100 amp service and I used #1 aluminum, if I remember correctly. You can google what size to use based on load.

Edited response. I just checked a chart and for a 100 foot run 100 amp 240 volt service, 1/0 aluminum is suggested, or #1 copper.

Magdump · Dec 9, 2018

Definitely no on the aluminum. I’d go with the rec you got from the electrician at the very least, considering the amperage drop on those big motors can burn stuff up. You’re at that magic 100 foot where things can get nasty. You also have to figure in whatever length is hardwired in your shed per circuit. 6ga copper for anything 220 is my minimum, but that kind of length I’d go 4ga at least.

Danny Abear · Dec 9, 2018

Look at the service feeding your house, prob not too much, may be better/cheaper to put new service to the shop

Nail Gun · Dec 9, 2018

Thanks for the info guys. You confirmed my fears...

The service I have gives me the most direct run to the shed. It also has two open slots I can tap into.

If anyone had at least 95’ of cable in good shape hit me up please. I have added some tools for trade in the General Marketplace. Some of the pics didn’t upload so you’ll have to hit the links.

Thanks!

SVTFreak · Dec 10, 2018

If I'm not mistaken, aluminum won't meet spec in a house. Too much expansion and contraction with heat and then chance of loosening and arcing. I would not use it in my homes panel.

I ran #1 3 conductor (+ bare ground) thhn on my 100 ft run to my shop. That puts it good for about 130-145 amps depending on temp. Then I put a 60 Amp breaker. I can always up to 100 Amp if needed. When my 220v compressor kicks on, lights don't even dim. I weld with a small mig with no trouble. Price on cable online wasn't bad. I think I got it from Houston wire and cable maybe? When though I did it myself, I sat down and showed a licensed electrician my plan to make sure it was safe and functional.

FYI, table for info
https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/

LACamper · Dec 10, 2018

An an insurance agent I started twitching when you mentioned using aluminum! We attributed a lot of the home fires (not to mention trailers!) to the aluminum wiring of the 60's. Take that roll to the nearest metal recycler and cash it in.

TooOld · Dec 10, 2018

I'm no electrician, but I have been running a 220 table saw, air compressor and wood planner in my shop for over 30 years. If I remember correctly, my feed is either a #2 or #4, 3 wire and have never had any problems with anything in the shop. The reason for this is because I only use one of the 220 volt tools at a time, I have no reason to run any two at once, if I'm planning then the other two are off, same with table saw. Only time I use the compressor is finishing projects or cleaning up in the shop. Like STV, my lights do not even blink when powering up one of the tools. So with your set up, I think you would have to figure at least two pieces of equipment running at the same time being you have AC (sure wish I had that in the summer LOL).

With the above said, I also believe bigger is better and safer, but we also have to look at costs. Only other thing, I'm not sure of your building codes and if the parish, town, or city requires a building inspection (mine did not, I built before all those requirements).

MRBULLRED · Dec 10, 2018

I would believe a 60 amp sub panel would be sufficient for what you want to run off of it. However I've included recommendations for both aluminum and copper 100 amp & 60 amp service with a run of a 100ft.

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swampfoxx · Dec 10, 2018

Most modern panels are rated AL/CU, and there is a dope that you can apply to the aluminum cables to prevent the corrosion.

340six · Dec 10, 2018

swampfoxx said:
Most modern panels are rated AL/CU, and there is a dope that you can apply to the aluminum cables to prevent the corrosion.

That is what Entergy did where the lines meet the panel. They had to run a new line to my meter panel. When my home was elevated the had to put it back onto the panel. FYI used a,large aluminium cave to feed all the homes here. But everything from that point on here must be copper or at least that was what the inspector said.

Nail Gun · Dec 11, 2018

That’s great info guys. Thanks, you saved me a bunch of trouble.

frhunter13 · Dec 12, 2018

If you think copper cable is expensive, what about burning down your shed? What you describe is probably a 100 amp, 240/120V requirement of 2C AWG 2 with a No. 6 ground if you balance your 120 pretty well. Copper wire is less likely to expand and contract so as to create loose connections over time.

Thoughts from an EE.

Electrical Supply Question

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