Another 220V question...which way to do it?

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Forum topic by mtn_goat posted 08-10-2010 08:19 AM 1348 views 0 times favorited 8 replies Add to Favorites Watch
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11 posts in 3135 days

08-10-2010 08:19 AM

After reading a myriad of posts regarding how lumberjocks have wiring their shops with 220V, I’ve decided there are as many ways to do it as their are shops! If you will indulge me one more question about the subject I would be grateful: First, a little background. I am looking to wire a small outbuilding for my tablesaw and a few other tools to give myself a dedicated woodshop. I would like to have 3 circuits…Lights (110 15A), TS (220 20A), and outlets (110 @ 20A). The building itself is only about 10 ft from my house, but the main panel is approx 50’ away by way of crawlspace. My question is what would be the more acceptable (and cost effective) way to run the wire. run 3 circuits from the main box to the outbuilding…romex in the crawl space? or would putting a sub panel in the garage to feed the three circuits be a better way to go. A complication may be that the building sits on a slab of concrete (old RV pad) making the use of a ground rod at the shop difficult. I would appreciate any advice those clearly more skilled than myself can give. Even if there is a different prospective I am not seeing?
Thanks to all.

8 replies so far

View TopamaxSurvivor's profile


18424 posts in 3915 days

#1 posted 08-10-2010 09:04 AM

Code says you have to have a disconnect at or in the separate building. That means a feeder for the panel with a main in it or a disconnect switch that opens all current carrying conductors.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Gene Howe's profile

Gene Howe

11163 posts in 3668 days

#2 posted 08-10-2010 01:36 PM

”Code says you have to have a disconnect at or in the separate building. That means a feeder for the panel with a main in it or a disconnect switch that opens all current carrying conductors.”

That’s the safest method.
Sink the ground rod as close to the outside wall where you mount the box. Run the solid copper wire through the outer sheathing as close to the floor as possible (above the plate) and up the stud closest to the connector in the box.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View bill1352's profile


130 posts in 3361 days

#3 posted 08-10-2010 02:54 PM

I wouldn’t think of doing it without a panel in the out building. If not for safety then ease of use. You know what you want or need now but how about 6 months from now or a year. The day will come when you mumble to yourself that a line right here would be nice.

-- Keep Your Stick On The Ice

View MedicKen's profile


1615 posts in 3702 days

#4 posted 08-10-2010 03:02 PM

Call an electrician

-- My job is to give my kids things to discuss with their

View SnowyRiver's profile


51457 posts in 3720 days

#5 posted 08-10-2010 03:10 PM

I would do the separate panel in the shop too.

-- Wayne - Plymouth MN

View mtn_goat's profile


11 posts in 3135 days

#6 posted 08-11-2010 05:06 AM

Thanks! it seems there is a consensus. Separate in panel it is.

View Lalaland's profile


44 posts in 4218 days

#7 posted 08-11-2010 05:38 AM

Another thought, go bigger than you think you need. It won’t cost much more now, but re-doing it will add much more. If you think you only need three circuits, add a big enough wire to increase the ampacity. You won’t regret it.

View canadianchips's profile


2616 posts in 3237 days

#8 posted 08-11-2010 05:56 AM

Definately. SEPERATE panel in the shop. Drill hole through concrete pad, pound the ground rod in. NOT A PROBLEM.
Call a local “SPARKY” for advice as well.
Trying to save money on electricity to shop in the short term WILL COST you money in the long run.
Burnt out motors because of drop in voltage.
Electric shocks due to poor ground.
And lastly you DO NOT want a Fire because of wire over heating !
Please take the time and do it right.

-- "My mission in life - make everyone smile !"

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