All of the outlets in my gargae (my workshop) are 110 on a single 20amp
breaker. I would like to add some 220 outlets for my belt sander, table
saw, dust collector, etc. I have an unused 40 amp double pole breaker and
room for several more breakers. The questions I know to ask are listed
below. I'm sure there is more to it than that. If anyone knows of any
links to articles about wiring a workshop, they would be greatly
What guage wire do I use?
How many breakers do I need?
What amperage should they be?
How many devices can be run per breaker?
The general rule is:
14 gauge for 15 amps
12 gauge for 20 amps
10 gauge for 30 amps
For long wire runs, you need to increase the sizes, but assuming the
breaker box is in your garage, you should be able to reach anywhere in
the garage with the above. If you're putting in 220V outlets for
machines, go with all 20 amp circuits (even if the machine only requires
15). Some day you'll get a bigger machine and you'll be kicking
yourself for not putting in the 20. The extra cost is trivial.
One per circuit :-) How many circuits do you need? One way to do it is
to put each 220V outlet on its own circuit (this may even be required by
code), but in practice, in a one-man shop you could have multiple
machines sharing a single circuit because they'll never be on at the
same time. You want a separate circuit for your dust collector, because
that WILL be running at the same time as another machine.
Greetings and Salutations.
First off, I am not a licensed electrician, so these
are only personal opinions...not legal guidelines.
This gets kicked around REAL regularly on the metalworking
newsgroup. While this is not a Black Art, the most complex thing
about it is that every local has its own variation on the NEC
standards. The best thing to do is get a copy of the building
codes from your local government, and, use them at guidelines.
Remember, though, that they are the lowest common denominator
so, I tend to prefer to go one step up. If, for example,
the code calls for 10ga wire I will use 8ga. If it calls
for plastic conduit, I will use metal.
That depends on a couple of things, including the
maximum continuous amperage you are going to be pulling,
and how the wires are run (Nomex, or through conduit...)
One breaker for each circuit you are going to
See above comment about the wire size. However,
the bottom line is that the breaker will have to be
bigger than the MAXIMUM pulled amperage expected.
One less than causes the breaker to pop?
Again...this is a code issue. There may be limits
as to how many sockets you can put on a single run,
or, it may be an issue of how much power you are
going to pull. Local codes will answer this
(even if it IS in an obscure fashion).
The bottom line is that you want to have
wires, breakers and sockets set up so that the
electricity will happily run through and do
useful work without heating things up to a
dangerous point. Electricity can be your
friend, but, alas, it is a ravening beast
when it gets free. You also want to be sure
that the wiring is done in such a manner that
it is protected from impact damage (which is
a likelyhood in a shop). I believe that,
because of this, code calls for wiring
to be enclosed, either in a wall, or in
conduit when it drops closer to the floor
than 6' (I forget the exact number, but
that should be close enough).
Although an electrician is not
cheap...it can be cheaper to have one
come in and do the job than do it oneself,
simply because it will get done quicker, and
is more likely to pass inspection.
I and many others have gone through the same thing you are going through.
For what its worth, let me tell you about my final solution and the reasons.
I ended up running a new feed to my shop to a new panel. It was fed by a
branch breaker in my house main panel. Whereas this sounds like a big
effort and expense, its actually no more effort and expense than running
just a circuit or two from your existing panel. Its amazing how cheap a new
panel with a few breakers is. Here's a list of things I did:
1. 60 amp 2 pole branch breaker added to existing home panel to feed shop
2. #6 INDIVIDUAL stranded wires (red, white, and black) for power, #10 green
stranded for ground
3. Run feeder wires to shop outside in 1" PVC conduit mounted under eave of
house (garage is semi-detached)
3. New panel in shop (about $18)
4. New breakers in new panel ($6-$8 each)
The total parts cost was between $150-$200.
Individual wires are cheaper and much easier to deal with.
If you do this, you will pat yourself on the back every day for the next two
years. For a one person shop, this scheme will run just about anything you
can throw at it. Those who have ample power to their shops smile every time
the table saw, dust collector, lights, and compressor are all running at the
As to books, I highly recommend "setting up shop" by Sandor Nagyszalancszy,
published by Taunton press. Its got chapters on all the key topics that
people worry about in putting a shop together. The chapter on electrical
power is pretty decent with good pictures.
12 (assuming you have nothing over 20a) unless the run is over 100', then
10. 12/2 is fine for purely 240v, but you might want to run 12/3 just in
case you some day want to use it for 120v also.
One double per circuit.
20a for a 20a circuit.
Devices or outlets? As many outlets as you want; as many devices as you
have power for.
The important thing is to figure out the amperage requirement for everything
you will be running, and then figure out what will be run at the same time.
I can run my TS (9a) and my DC (8a) together on a 20a circuit, so I only
needed one. If your equipment is bigger, you might need 2 or 3. If you are
getting up to 3 circuits needed it is probably just as easy to put in a
subpanel, as someone else suggested; especially if your panel is crowded or
240v is no more dangerous or difficult to install than 120v, but unless you
are sure you know what you are doing (and having to ask these questions is
not a good sign) it is best to get someone who does. There are a lot of
little things that have to be done right for a safe (and legal)
installation; they are not difficult, but you have to know what they are.
It is also good to ask your town if they have any special requirements
regarding conduit, inspections, or anything else.
On Sat, 24 Jan 2004 17:07:00 +0000, Bob Bowles wrote:
Find an electrician who will let you do all the work. Pay him for advice.
Electricity is nothing to fool with. Unless you can be absolutely
certain the advice you get from newsgroups is correct, you are taking
People get hurt and fires start from poor wiring jobs.
Well I'm a qualified electonic engineer and back where I come from all
power is supplied as 240V 13amp. None of your whimpy 110v torch
stuff for us Brits, if you don't come close to killing yourself when
electrocute yourself what is the point?
Now I am living in the US I am trying to work out what is really
in adding some 220V outlets to the basement to power my table saw,
Would it be necessary to upgrade the power hookup to the house or is
the standard supply balanced 110V 0 -110V so all the electrician has
to do is
stick a circuit breaker in across the 110V and -110V to get 220V?
If I turn out to need to upgrade the power hookup to the house anyway
(we have several breaker panels already) what is a reasonable fee? I
quoted $3,000 which seems rather a lot to run a wire from a utility
20' from the house.
Depends on how old your house is. I would guess anything built in the
last 30-40 years or so is likely to have 220V service. Before that,
Look in your circuit breaker box. Do you have any 220V circuits
already? They typically look like two regular circuit breakers with the
handles bolted/riveted together. In a single-family house, the most
likely uses would be really big window air conditioners, central air,
electric heat, electric stove, or electric dryer.
The real test is to open the breaker box and stick your tounge on the
bus bar. If your toenails curl up, it's 110. If your belly button
inverts, it's 220.
It's not just a new wire. It's a whole new breaker box. Not to mention
a new meter and perhaps conduit to/from the meter.
I was about to say that this should be attempted only by
professionals, but then I recalled the story I heard about
a "professional" electrician who decided to measure the
voltage across the 13.8KV lines with his 600V VOM! He
was lucky to be only temporarily blinded and deafened by
the flash and boom that followed and the burns were minor
when the test leads vaporized. The meter was a total loss...
I can't seem to find the 240volt service in my new shop. I wired all day
and the inspector even signed off on it today!! and not a 240volt service to
be found in the whole place:-)
firstname.lastname@example.org (Phillip Hallam-Baker) wrote in
I just did the same thing, including emigrating from the uk. I found that
getting a definitive answer on code related stuff is often difficult and
confused here, with enough leeway left to the inspectors interpretation
to make life irritating. Heres my experience in FL, it will probablt be
different anywhere else..
It depends upon your local codes but usually the utility company owns the
wires up to the house attachment. You own the wires from that point down
into the meter and on. If you need to upgrade the panel or have work done
on it then generally a contractor is necessary or someone who is
registered journeyman or master electrician and insured for the job...
again a local city codes issue.
They or you will have to pull permits for the work and have the work
inspected. The contractor will do the work changing everything related to
the panel including upgrading the meter if necessary, up to the utility
attachment point but not running wire from the utility pole. The
contractor should organise with the utility co to have the run to the
house upgraded if necessary.
I just upgraded my panel to a 300, involving a new panel and meter but no
new wiring from the utility required. The total cost was a little over
$900 in FL. I also ended up correcting a lot of issues post contractor
(no 'earths' connected, no leg load balance, dedicated earth for computer
stuff, shop subpanel) and had it re inspected by city without issue.
As you say unlike home with 220 lve, neutral and true earth, here the
panel usually has two 110 legs and a common neutral bus. I was suprised
to see that the panel case was earthed to a ground rod and house plumbing
but the house circuit earths actually went to the common neutral bus and
so back to the utility.
The legs are generally alternating down the panel so if you have a 110
circuit the breaker is one slot wide and attaches to one leg. For 220 the
breaker is two slots wide and attaches to both legs, with the socket
having either three or four conductors depending where you are and age of
the house, two 110 legs and neutral / earth or separate neutral and
earth. Confusingly the code in FL required a four conductor setup for my
220 shop subpanel and actually produced a setup where the neutral and
earth on the four wire both being terminated on the same neutral bus on
the main panel......
hope thats of use
I'm not sure what you got from all these answers.
Your feed is 120/240, as tou suspect.
All you need is a double breaker and three or four wire cable. Four wire
gives you slightly more safety and is in most codes now. 120 outlets in
basements need ground fault protection. You can do it with a breaker
(expensive), or with GCFI outlets. One GCFI outlet can feed others
Myself, I don't use four wire or GCFI on my 240 outlet.
Look at your box. You should find some double breakers for stove, water
heater, or air conditioner.
All you need is 12 ga wire, 20A, for any reasonable shop tool. If you only
run one at a time, the 30A breaker will do it. That said, it only costs a
tiny bit more to pull a 10 ga wire and put on a couple of outlets for who
Having a local electrician pull one circuit "should" cost only a couple
hundred bucks, but there are plenty who will gouge you. Get some bids and
ask friends for recommendations. But if you are comfortable with working in
the box, then it's no big deal. Just don't use it as a learning experience.
We don't like to lose members unnecessarily!
Yeah, and you guys put those silly fuses in all your plugs. I kept thinking
I had a bad run of extension cords when I lived in Ireland, than discovered
they had 5 amp fuses in the plug. I replaced them with 13 amps and did not
report myself to the electrical police.
...Ireland apparently adopted the UK standard...equivalent of a plug in the
US that we would use on an oven but needed just for a table lamp. Our
little plug end is HUGE in the UK.
I guess it is due to some fire that they had about a million years ago
(ok...was less than that but I'll have to add that it was a blessing in
disguise as it burned all the black fever carrying rats) they are obsessed
with fire. They don't trust the circuit breakers, which trip with static
electricity on the carpet, so they also insert an in-line fuse in the plug
Can't get much closer than that, can you Moe? I think maybe he was being a
little humorous. Strong Brits, using the he-man electricity and all vs us
with our wimpy little 110. Sounded funny to me and I'm not even British.
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