Electrical Question - New Detached Workshop, 100Amp Subpanel

[Bob Kinsman]

House three way switch or low voltage goes along with what I would recommend. I also accomplished this same detached garage sub panel a bit over a year ago, using 3 #3thhn hots/neutral 1 #6thhn ground in conduit. I only feed the sub off a 60amp breaker but wanted to have the correct cable in the ground if I ever got the itch for 100amps.


Suggestion: Make sure you put two tubes of conduit in the ground while you have the trench open for the power!

'Cause someone's gonna think cat5e or coax goes mighty well with a well supplied shop!

[Jeff Caulk]

I'll leave the electrical code to the experts, but the schematic above is what I understand and how my shop is wired.

As for capacity, I have a 20 x 40 shop on a 100A sub panel fed with a 100A breaker.
Rememeber that's 100A per each 120V leg.
I have three 20A 240 circuits, dedicated table saw and dust collector circuits and a third for the band saw and jointer (only use one tool at a time).
There is a 20A 120V general lighting circuit, an exterior 20A security lighting circuit, five 20A receptacle circuits, a dedicated 20A compressor circuit and a 20A feeder to another outbuilding.
I have two double space couplers for my automated lighting system.
With all that I still have 6 spaces open.
100A is more than enough capacity for a one man shop.

I ran conduit for power between the primary building and the shop along with two additional conduits for LV wiring.

[Richard Yeskoo]

Is there a disconnect at the pole or just a meter?

Both meter and disconnect.

[Lewis Anderson]

Both meter and disconnect.

Per current code the ground should be bonded at the disconnect and you should have a 4 wire feeder going to the house. If that is the case than it would be easy and up to code to tap on after the disconnect to feed the outbuilding with another 4-wire feeder. If not, I would recommend, as mentioned above, speaking to your local inspector or electrical contractor to see what they will accept.