Wiring a basement shop

[Sean]

OK guys, here is some background. I am not an electrician but I have completely finished 2 sizable basements in previous homes and did all the electrical by myself following all code guidelines etc. I never had a problem and consider myself pretty good at it.

I have a new house now that is a ranch style with a partially finished basement. I already built my shop in a back corner of the area (about 250 sq feet). When I return home after the Holidays, I am going to expand the shop by about 300 sq feet. I have a full complement of power tools including PM 64a saw, Jet 6" floor jointer, Jet Planer, Delta Drill Press, Jet air filtration, and Jet model 1100 dust collector.

The problem is, the house is brand new and the breaker box is in the garage. There is no way to run new wiring from the box to the basement through walls becase the garage is on a cement slab. The builder did put two 20 amp spare breakers in the box and ran them to a dead outlet in the basement. I used these to power my existing shop space. I used both circuits and powered two outlet boxes with each (for a total of 4 boxes) They were located so that the large tools would be on separate circuits. I expanded the lighting for the new space by tapping into the existing circuit that the other lights in the basement were on (I added 4 porcelain single bulb lights that have 75watt bulbs in them) I also added a small flourescent light over the bench which is plugged into an outlet that screws into the light socket. So... the lights are on a different circuit than the tools.

Now for my question. Is there a way to install a sub panel in the basement. If so how could I run the wiring to the main panel in the garage. Also, to throw another wrench in the equation, as mentioned, the builder put two spare 20 amp breakers in the box but that completely filled the box and there are no unused spaces).

I guess another solution would be to tap into the 20 amp outlets previously wired and add new outlets in the expanded space. I just do not want to overload the breaker obviously. Does running new outlets in itself add to the load or is it only if a tool is running. Also, I am going to need alot more lighting. Should I continue to tap into the overhead light circuit already there???? What is some good lighting that does not take too much ampage??? How can I calculate the appropriate number of lights that can go on a single 15amp breaker.

Long post, I know but any help would be appreciated.

P.S. The talbe saw is not 220. I would like to someday do that but based on what I have explained....I do not know if that is possible.

Thanks for your help!!!!

Sean.

[Lou_williams]

"The problem is, the house is brand new and the breaker box is in the garage. There is no way to run new wiring from the box to the basement through walls becase the garage is on a cement slab. The builder did put two 20 amp spare breakers in the box and ran them to a dead outlet in the basement"

The above it the key. I don't know the relationship between your gargage and the basement. But wires had to be run between the two locations. You can't directly run wire though cement. So the wires had to be run through conduit or through the walls. In both cases you should be able to run new wire along the same path.

What I would do is replace the two existing 20 amp breakers with a single 220 60 amp breaker and run the new wire to support this breaker, I don't have my code book handy but that would be # 4 or 6, But a sub panel in the shop. The two existing 20 amp breakers and circuits could then be rerouted to the new panel, you could add a new lighting circuit and new 220 amp circuits to support your tools. I would use one 20 amp 220 for the tools and one 20 amp 220 for DC. I would also add one 20 amp 220 for a future large compressor.

Lighting circuits you want to limit the total current to about 3/4 the breaker limit. So for a 15 amp breaker go a max of 10 amps, That would give you about a total of 1200 watts of light on one breaker.

In a shop it is also a good idea to have two different lighting circuits. As far as how may plugs you can put on a circuit, there may be local code issues, but in a shop environment with only one user, it does not matter how may plugs are on the line. YOu just can't draw from all more than the rated amount.

To find out how to route the wire, check and see if the builder will tell you how the wire was feed. Open the drywall by the panel carefully. Find the electrical sub and ask them how they did it.

good luck.

[Chagrin]

For wiring the subpanel, the solution that seems obvious to me would be to run the cable for the circuit to the subpanel through the path that your already existing 20A circuits use (and then wire those 20A circuits to your new subpanel). You'd take out the two breakers for the 20A circuits and replace them with a double pole breaker for the circuit to your subpanel.

Adding additional outlets to the circuit can be problematic if the circuit gets too long - the rule I generally see is 50'. The long circuit drops the voltage to outlets on the far end. The easy solution is just to replace the 20A breaker with a 15A breaker.

The most efficient lighting is flourescent.

A 110V, 15A circuit is capable of carrying 1650W (V * A = W, or 110V * 15A = 1650W). This is not to say that you should completely fill the circuit - hopefully another soul can detail the appropriate fill percentage (IANAE). Basically, just total up the wattage of your fixtures and keep it under 1650W.

...hope that answers your questions. But now for my question: do basement shop circuits require a GFCI?

[Sean]

Thanks. But I think I have other problems. The main panel is on the far left side of the house and the area of the basement where the shop is is on the far right....a distance of about 70 feet. All the walls are finished drywall with paint. Your reply got me thinking and the wiring route for the basement circuits may go up through the wall into the crawl space in the attic and over the house and down through a wall, or it may go horizontal on the wall of the garage accross half the house (and of course through hidden studs in the wall), and down through the floor. In any case it seems as if major destruction/construction would have to be done and I do not know if I am up to it.

Is there is possibitly of replacing the 20 amp circuits with 30 amp or more in the same space??? Would this create more capacity for my existing outlet run???? Or, would it make sense to replace the 15 amp circuit that powers the existing lighting run with 20 amp or more for the same reason???? I don't know, but maybe a 220 is not feasible for me now but am wondering if there could be another solution to increase capacity safely.

A possible alternative solution for the subpanel..... Can wiring be run outside of the house and around the house and through the other wall???? Would an electrician in his right mind do that???

Perhaps thats the key. Maybe its time to get some professional help.

Sean.

[Sean]

I am not sure if GFCI is required, but I plan on having the initial outlet in the run GFCI anyway.

Sean.

[Keystone]

Sean

What about running it outside along the house and re-enter your shop? Bury the line of course.

[Lou_williams]

For the existing 20 amp line you have 12 gauge wire. For a 30 amp service you have to use as a min 10 gauge. I think the best bet is to wire outside.

[Super Ry]

I can say out here in AZ they sell this stuff called UF (underground feed) wire. Its real heavy stuff with extra insulation. Some city codes will let you run this stuff underground just by itself. I always run it inside someithing if it's not inside a wall.

My vote id be to run new lines outside the house using UF inside some nice heavey conduit. 220 would be nice but it does complicate the wiring a bit.

Good luck and congrats on the new LARGER shop!!

[Frank]

You'd better check up on running insulated wire thru conduit- that's a big no-no. Too much insulation inside conduit can cause overheating, causing insulation break down, causing short, fire, etc...
Sean- sounds like you're on the right track. In situations like what you describe, we usually bury it, but going thru an attic can save a lot of digging. Keep us posted and good luck!

Frank

[PastorPaul]

Frank,

I had four brothers that were electricians. They rarely ran wire underground, even the stuff designed for that, without conduit. They just made sure that the conduit was large enough to allow some air space around the wire. That also made it easier to run new wire in the future if necessary.

Pastor Paul

"If they don't have woodworking in heaven, I ain't going!!!"