Garage shop wiring


Old 07-05-04, 11:59 PM
Thread Starter
Join Date: Jul 2004
Posts: 36
Garage shop wiring

Hello all. I do some woodworking in the garage, and for the last couple of years have had no issues. My wife bought me a new table saw for an early birthday present, and it's just a TINY bit strong on startup for the 15A 120V circuit.

I'd been leaning towards upgrading out there, but until now didn't have a valid enough reason for the little woman.

Currently, we have a fusebox with, and I'm guessing, at least 100A service. We have a 24 space box, with 10 of the plug fuses, and 6 of the bayonet fuses. Here is the layout of the box, along with the assignments for each. We have 2 open.(15,16) To the best of my knowledge, 17 is unused as well.The ones for the range are unused. The assignments were filled in by wife's father when he lived here, and we now have a gas range. I 'm posting it to give an idea of our power supply, and to confirm whether my estimations are correct.

Our meter reads CL200 240V. If I'm right, that means it's rated for 200A, and 240V.

I would like to either add a 60A subpanel in the garage, by tapping into the meter via the knockouts, and running 3 or 4 ga to the garage in conduit, or tap into the unused circuits from the range.

The garage is attached, and around 30 feet from both the meter and the main panel, which are piggybacked. It's 20x24 feet, with 2 existing 120V outlets. Fire rated 5/8 drywall with R-13 insulation stapled to the studs.

Ideally, I would keep the current circuit to the garage from the main panel for the lights and garage door opener. The subpanel would be nice because I would have fast access, and it would be outside the main part of the house. I would like to have one 240V 20A circuit for the table saw, which can be wired for 240. The others would be 120V 20A. I would like to add one, possibly 2 240V outlets, and 2-3 120V outlets.

Typical load for the house when I'm working out there isn't high. In the spring/summer the constants are 1 TV, 1 refrigerator, 1 upright freezer, and 2 or so fans, as well as 2 ceiling fans. Sporadic loads include a microwave, a washing machine, and the A/C. In the winter it's basically the same, minus the fans and the A/C and plus the furnace. Also if I do this, I may work out there in the winter with an electric heater.

Does this sound like a feasible plan based on my description of our service and supply panel?

Also, would the lines for the 240V and 120V circuits be run separately from the meter, or is one line run from the meter, and they're wired separately in the subpanel?

I understand that the 240V has two hot wires, the neutral is not necessary, but the ground wire is imperative. The house was built in '67, and I imagine it's grounded to the cold water line. Should I have a separate ground for the subpanel, and if so, where would I locate the grounding rod?

If the subpanel isn't feasible, how complicated would it be to re-route the unused circuit from the range? Could I also run that outside to the garage.

Are those enough questions?

My level of knowledge is above fundamental, but far from profound, so be gentle with me.

Thanks in advance!


Last edited by DaveK145; 07-06-04 at 12:01 AM. Reason: Typographic error in title
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Old 07-06-04, 05:37 AM
Join Date: Dec 2003
Location: Minneapolis, MN
Posts: 80
Well, first thing, from the diagram you linked to, you have a 60A service, not a 100A service. This doesn't preculde you from doing what you want, but it is worth noting. The rating on the meter only describes what it is capable of, not what service you have, or what your wiring can support.

If I read the diagram right, each 240V circuit uses 4 spaces, so
17, 18, 19, 20 are the A/C. Not just 19 & 20.

You cannot add your new panel to the meter directly. It must be connected to your existing fuse panel.

You could repurpose the 240V fuses that used to be for the range, though without knowing more it's not possible to say if the fuses could safely be upgraded from 30A.

But, with the number of circuits you want to add in this subpanel, in my opinion, you're looking at far more than a 60A service should be expected to provide.

I'd look into getting the service upgraded first. And you'll want to have a professional electrician do that (unless you like not having power for days while you coordinate the power company and inspector).
Old 07-06-04, 09:12 AM
Thread Starter
Join Date: Jul 2004
Posts: 36
I was wondering about the way the bayonet fuses were laid out. I read something in a different post, but I guess I was just being cautiously optimistic.

I spoke with someone about it who said they had worked with things of this nature and they thought otherwise, but it's entirely possible they read the diagram wrong. I had no idea, myself. That's why you seek out second opinions.

Anyway, I appreciate the response. It certainly opened my eyes some.
Old 07-08-04, 03:44 AM
Thread Starter
Join Date: Jul 2004
Posts: 36
Okay, another question: If I upgraded the service to the house, would there likely be partial or total rewiring involved? I'd actually welcome the upgrade to a breaker panel, and I would likely keep the current circuits at their current amperage, then have new ones installed and run out to the garage rather than installing the subpanel.

I wish I could figure out more about how the circuits in this dang place were run without unscrewing fuses and running around with a multimeter. What I listed on that layout image was my best interpretation of what was written on it by the previous residents. Some of the entries make no sense at all to me. My wife has lived here for over 30 yrs., and I've been with her here now for 10, and she says the wiring hasn't been touched since she's been here, save a new meter.

Couple that with how randomly it seems they chose to run the circuits, and it's frustrating. The one circuit controls fixtures or outlets in 5 different areas of the house on 3 different floors.

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