Electrical for a workshop/garage.

Cliff_Johns · May 11, 2004

I'm working out plans for a workshop/tractor shed/garden shed. It's really a 14X20 concrete floored garage in my back yard.

The question is, what the electrical design will look like. For my needs now, a 110 plug on each wall, and one on the ceiling for an opener plus a switched one on the ceiling to plug lights into would be sufficient. Maybe some coach lights on the outside.

But, I am thinking about taking a welding class later this summer and I would regret having to redo this if I decide I like welding and want to do more of it. If I want to do some welding, should I have 220 run to the workshop? 20 AMP circuit enough for most work? Or could I get along with a 20 AMP 110 circuit just fine?
Cliff

Junkman · May 11, 2004

The answer to this question is dependent on what you want to spend and how much you think that you will ultimately need. I have a 200 amp service in the house and I have pulled off a 100 amp service for my garage sub panel. I know that I will never need that much power, but it is inexpensive when you are doing it yourself. Materials is the only cost. I purchased the 100 amp Square D main panel used at a local flea market and it looks like new. It cost me $10, or $13 if you figure the cost of parking. It was full of breakers also. No matter what I will want to do in the future will be hampered by not having the power to do it. Try to plan ahead for the future as best as you can and you will never go wrong...

JimR · May 11, 2004

I installed a 200 amp system in my house when I added on the second story in 93. I took the old 100 amp box and installed it in the garage. I have each wall covered with plugs. I installed a 50 amp plug for my welder near one of the garage door. I have a 30 foot extension should I need to weld elsewhere in the garage that I can't reach from there. I also have a 30 amp plug for my air compressor under the stairway that goes upstairs. Make sure you use 20 amp plugs and wiring in the walls. I used 15 amp and wish I hadn't. Put in a sensor light outside so that it goes on when you get near the building. It makes life easy at night when you are heading in. Run 220 out there.

Boondox · May 12, 2004

Cliff -- I agree with the others that you can never have too much power. I have 200 amp service to the house, and a 100 amp sub-panel in the shop. While the shop was being rebuilt I carefully sketched out where I wanted the outlets to go (4 20 amp 110 circuits and 3 20 amp 220 circuits) but I didn't lay them out right away. After the shell of the shop was up, I brought in all my tools and reorganized several times. Only when I was satisfied that the layout was the way I wanted it was the wiring installed. One of my better decisions!

Have fun! Pete

Henro · May 12, 2004

At the risk of sounding like an echo...I put a 100 amp panel in my shed...mainly because of the welder.

Each welder has its own current draw, but I would bet you would want a minimum of 50 amps available if you are going to do and welding of fairly thick material with a stick transformer machine.

Like Junkman said, if you are doing it yourself prices are not too bad for electrical panels. Actually cheap if you price them in sheets of plywood rather than dollars! Can you see the shock on my face? I noticed 1/2 inch CDX plywood priced at $20 per sheet at Home Depot yesterday /forums/images/graemlins/frown.gif. Must have had my head in the sand for a while... /forums/images/graemlins/crazy.gif

The important thing is to get a large enough panel installed and wired up. You can worry about using the power later, like Boondox did.

Learning to weld opens the gate to a whole new "do it yourselt" world. If you take that class, and are like me, you will wonder why it took you so long to learn the skill. My guess is that you won't regret putting in enough house power... /forums/images/graemlins/smile.gif

Cliff_Johns · May 12, 2004

Well, thanks everyone. I guess I already knew, but I was hoping I was wrong. Problem is I live in town and they require everything that can be required when it comes to building codes. Even in a detached garage without wall covering or insulation, they require conduit, for example. They also require that electrical work be done by a licensed electrician. Somewhere around $1,200 for running the wire 40 feet across my basement, and another 40 feet underground then putting in an 50 AMP subpanel and outlets. (plus $100 for permits) They will let me dig the trench for the outside run if I ask nice.

I'm hoping I can find an electrician who will let me do most of the work, then just look it over to make sure everything is done correctly and do the final connections, but they're not reallyt supposed to do that and even that is going to cost me.

Oh, well. I'll bite the bullet now, or I know it's going to annoy me for many years to come.

Thanks again,
Cliff

DaveNay · May 12, 2004

Cliff, I am fairly sure that code in Illinois allows the homeowner to do all of the rough and finish electrical work themselves, as long as all of the appropriate permits are pulled, and inspections are performed.

But then again....you do live in a fairly conservative area, known for having ridiculous requirements, so the local town regulations may be taking precedence.

Dave

Cliff_Johns · May 12, 2004

( But then again....you do live in a fairly conservative area, known for having ridiculous requirements, so the local town regulations may be taking precedence.
Dave )

You got that right. I have a suspiscion that many of the rules they impose for my safety are actually to keep any inexpensive housing out of the community. I will double check the town codes about doing it myself, but this is how I understood what the inspector told me. I don't mind having a licensed electrician look things over and do the final hookup, in fact I'd do that even if I didn't have to.

Cliff

EddieWalker · May 12, 2004

When I lived in California I had to have a permit for any home improvement valued at $100 or more. It was so rediculous that nobody bothered to get them. The city had an department whose only job was to find un-permited home improvement and construction jobs. Of course, they were underfunded and overworked, so it really wasn't a big deal.

The end result is the number of permits requested droped dramatically, but the amount of work was increasing tremendously!

I'm not suggesting you violate any law and just do the work yourself, since nobody will be the wiser and you'd save thousands $!, No, I wouldn't suggest you find out what the local code is for your area and just do it yourself, since it's such a simple project and an easy do it yourself job.

Depending on what you have available to your house will dictate what you can run to your shop. Do you have 200 amps to your house? If so, then 100 amps to the shop isn't an issue. Lots of older homes only have 100 amps.

If your interior walls are exposed, then you MUST run conduit. Grey plastic is cheap and easy to use.

I'd have a minimum of two outlet boxes on each wall and over your work bench I'd put in an additional two double boxes at a minimum. In my shop I'm running double boxes every ten feet.

It's just nice to leave the big power tools pluged in, like table saws, drill press, air compressor, chop saw etc...

Even if you don't have the tools yet, you will.

Another common mistake is not enough lighting. I used the 8 foot flourecent lights. Plan on lighting the work area. Too often lights are placed in the middle and when you're working on a vehicle or at a bench, the light is behind you and blocked by your body or the vehicle.

While your doing your 110 wiring, run the 220 for the welder at the same time, you don't need to connect it to the panel, or you can, but it sure is nice to have it all done at once.

Add a phone line while your at it. I made the mistake of thinking I had a cordless and didn't need a phone in the shop. Problem is I had to bring the cordless into the shop with me all the time, which I didn't do, and when I did I'd get it dirty or I'd loose it in a pile of sawdust. Put a cheap phone in the shop in a permanent location.

Depending on how your layout is, an additional door bell from the front door is also a nice feature.

Good luck,
Eddie

Cliff_Johns · May 12, 2004

Thanks for the advice Eddie. My wood shop is in the basement, but I may put a large resaw bandsaw in the outside workshop. I agree that lighting is key to any detailed work.

( If your interior walls are exposed, then you MUST run conduit. Grey plastic is cheap and easy to use. )

I didn't know they had plastic conduit. They don't sell it around here, metal is required. Other places I've been will allow armored wire for such installations (or they didn't care at all)

Cliff

EastTexFrank · May 12, 2004

Lots of good advice here. The only thing I'll say is, "Put in plenty of outlets" and put in the 240 volts now. When I had the shop rewired I put in 240 volt outlets for a welder, window a/c, table saw and dust collector. The window a/c was already there and I have picked up the rest over the last 7 years.
That's good advice about the lights too. I had 3 lights installed, one at each end and one in the middle. I also put them on 2 different circuits. If you throw a breaker and a light goes out, you will still have one circuit operating and light to reset it. I did that after a friend ended up with 8 stitches and a concussion when he tripped over stuff on the floor when when the light breaker tripped in his shop at night when he was piddling.
By the way, if you do nothing else, put in a 50 amp, 240 outlet for a welder. I started with a 110v mig and while it is a good machine and does lots of things well, it is limited. It won't be long before you are wanting a bigger 240 volt machine.

Cliff_Johns · May 12, 2004

50 amps at 220 volts! Good grief. Welding is expensive, and I haven't even taken the class yet.

Cliff

JeffRey30747 · May 12, 2004

All of this sounds like good advice to me. I can add:

More switched outlets in the ceiling. I use the 4' shop lights that you hang and plug in. If a ballast goes bad, you buy another light and plug it in where the old one used to be. You might even consider more than one switch. Half my lights are on one switch circuit and half on another.

Put your lights on a separate breaker circuit than your wall outlets. If your table saw trips a breaker, you won't be fumbling around in the dark to get everything back in service.

Jeff

uhmgawa · May 12, 2004

( ..and put in the 240 volts now.)

Assuming you are going to drop a subpanel in the new shop running a
240V lateral may be your only option. I don't believe I've ever seen a
120V panel nor would one make much sense. The intent is to distribute
the collective load over both poles of a service.

What you'll need is a main lug panel with as many breaker locations as
you can find. Don't scrimp here -- it pays to invest in the real estate for
future work. The panel cost will be trivial compared to the project
cost.

One important note is the subpanel needs to have a separate insulated
neutral bar in addition to the ground bar it will have by default.
The panel is then fed with a lateral consisting of four conductors (2 live,
1 neutral, 1 ground). You can typically buy the additional bar from
where you purchase the panel and just drop it in.

rambler · May 12, 2004

This is a really small shed, so we needn't get too carried away. It won't need _everything_.

Anytime you mention a welder or a real air compressor, you are talking at least 50 amp serive, 220. Anything less & you will be real sorry. Even if a small wire welder or compressor runs on 110, you make the lights dim if you don't have the 220 service to split from....

Since you need to hire it all done to be legal, there is only $200 difference in materials to go from a 20 amp 110 service to a good 100 amp 220 service. You'd be thick in the head to do anything less than the 100 amp 220 service! /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Not suggesting you avoid the legal regs, but once an electrician installs the basic 220 service & panel, most anybody can easily & without notice add more electrical outlets, lighting, etc. for the cost of materials & follow the code so it would pass any surprise inspection............

--->Paul

Boondox · May 12, 2004

Cliff -- Check on that prohibition on plastic. Most places allow either, though the metal boxes have to be grounded. I used plastic on my high amp circuits because the 10ga wire is a pain when it comes to multiple pigtails and the plastic boxes have greater volume. For the lower amperage circuits and those within chew range of the sheep I used metal. Nice installation, but not as easy to use as the plastic IMO.

I saved a small fortune by mounting the boxes/conduit and running the wires myself, then having a licensed electrician come in to make the connections and put his stamp of approval on everything. It didn't hurt that I got his blessing on the wiring diagram before the work started. He compared my work to the plan, grunted his approval, and spent less than an hour hooking everything up.

Good luck! Pete

Lazy · May 12, 2004

One important note is the subpanel needs to have a separate insulated
neutral bar in addition to the ground bar it will have by default

Hi could you give a reason why you need the insulated neutral bar?

Charlie

Inspector507 · May 12, 2004

In a nut shell.........you are not permitted to ground anything with the "neutral conductor" beyond the main disconnect. Hence a 4-wire feed needs to be run to the separate building if you run 220 out there. The neutral and ground cannot be connected together.

Lazy · May 12, 2004

Hi
what NEC article covers that requirement? I'm still learning when it comes to the NEC.

Charlie

johnday · May 12, 2004

What you are winding up with is called a subpanel. You not only have to "debond" your nuetral from the panel, you also have to be sure to "bond" your grounding busbar to the panel. All the reasons for this were once known by myself, but I can't recall all of them[ getting old you know]. I'm a carpenter anyway and picked up electrical when I was an apprentice electrician.
In some jurisdications, an electrical permit cannot be refused a homeowner. That is generally true in Michigan. Unless there is an ordinance of some type. I do all my own wiring and also help out "good homeowner friends". I'll have them pull the permit since I'm not licensed and show them what needs to be done. It's too bad you don't have that luxery. Don't claim to know more than a journeyman, but the inspector doesn't make any more than two trips. One for rough and one for finish.
Good Luck, let us know how it tuns out.
BTW, there is an electrical inspector on this site that could maybe help you out. Inspector 507 I think.