Very soon, I will be ordering a table saw, jointer, and maybe a
planer. Santa was VERY GOOD!!! All will run on 220. My shop has 220
at the box, at least 2 circuits. The previous owner ran a welder and
huge compressor, so the amps are there.
I did some wiring 25 years ago, but am a little rusty. I think I
want junction boxes every 6-8 feet or so around the shop, so I can plug
in things or move them to a different location. Is there a standard
plug, like a dryer or oven plug that I should use? Does it matter for
my shop? I understand I will want to keep the plug to equipment
distance as short as possible, but would like the ability to plug the
saw in on one wall, then maybe later on the other wall for a different
job, or for whatever reason.
Should I run separate conduit for the 220? I have 110 boxes every
six feet at chest hight currently, and it might be possible to snake
additional wire down the same conduit, and add a 2nd junction box for
Thank you all for your help and suggestions.
I used 20a 220 receptacles. It's very similar to the 120v flavor, but
one of the blades is horizontal rather than vertical. I believe it
uses the same faceplate, and plugs are pretty cheap. For 20A 220V
it's fine. The 30a or greater have those giant plugs, but for
converting shop tools to 220, 20A is sufficient. Realize all 120V
tools will run at 1/2 the amps on 220. You don't need 8ga wire and
30A plugs. I used 12ga 2-conducter (plus grd) wire, and 12ga cords
(bought long extension cords and cut it to size.. cheaper than buying
wire in bulk). I think most 1-1.5hp tools are wired with about 14ga
stranded.. I could have just used that. But I went ahead and rewird
with about 15-20' of 12ga stranded. I did this on my TS and Jt. I
just used the existing wire on my DC. I'm still running my BS and DP
Maybe an electrician can chime in here.. but I did some homework, and
simple 220V at 20A and below is pretty simple. I would not mix 120
and 220 in the same box.. but that's just me. Code might allow it.. I
just don't know.. but it seemed simpler for me to keep them seperate.
On 2006-01-30, nospam email@example.com
I've never seen where it was "legal" but my Practical view is that I
wouldn't do it even if it were allowed.
Even up to 60A (ovens) or higher is pretty straightforward. You decide
what ampacity you need by the nameplate of the device (required to be
accurate), choose your wire gauge based on your tolerence for voltage
drop, choose your conduit fill by looking it up in a table OR
Nothing about it is especially Difficult, but it Does require attention
Always work to your comfort level and call an electrician if any part of
the job makes you UNcomfortable, preferably before starting it.
My comfort level is, "If I can kill power and the source panel has
capacity. (space and ampacity) for the given job." YMMV and work within
your comfort level.
It's not a problem to mix 220v and 120v current carrying conductors
in a raceway (read: conduit), as the potential to ground for any single
conductor is 120v.
It is an NEC violation to mix 600v(for example) and 120/220 in the same raceway,
I didn't hear it, I was just guessing. My guess was based on the
safety factor - if you shut off a breaker to work in a box, it would
be dangerous if there were other live wires in the box. If each box
had exactly one breaker, shutting off one wire in that box shuts off
all the wires in that box.
My inspector's attitude is 100% health and safety - if it's safe,
he'll pass it, if it's not, he won't. It made it easy to guess what
Well, he told me what his attitude was when we first met, and his
actions backed it up. But, if you know something about my inspector
that I don't, please, let us all know about it.
For example, we were using a type of insulation he was unfamiliar with
it. Code said it was OK, but he also took a bit of it home to see how
it reacted to fire, just in case.
Since our town and state use the national code, I could probably argue
with him about anything that wasn't strictly code, but I'm not that
stupid. He was acting in my best interests, and it was obviously so,
and I was happy about it.
I'd bet a small sum of money, with no knowledge of your inspector that what
he really means is that if it meets code it's fine. Are you saying he
rejects wiring that is up to code because it does not meet his definition of
safety? Or perhaps even that he accepts things that are not up to code
because in his opinion they are somehow safe? I would like to believe he
does not view himself as above NEC and decides for himself what is safe. I
believe he probably relies on NEC.
And... I'll bet he passed it right? What did his "test" prove? Not to be
insulting, but this kind of inspector sounds like he is just entertaining
himself with his tests. He surely does not really believe that he is going
to somehow dismiss the findings of UL or any other industry certification
with his home grown tests, does he? My bet - no, he's going to defer to
If you're happy, then that's all that matters. You're wired to code and you
can't do any better than that, and you like what your inspector says. Don't
see how that suggests that he doesn't defer to NEC though.
Well, I've heard stories about inspectors that require more than what
code requires. For example, carpeting. Carpeting is not a health or
safety issue (assuming the underlayment is safe) but I've heard of
inspectors that require it for occupancy, and would fail bare floor.
No, obviously he requires the house also meet code. There's more to
an inspection than code, though. And there's more to an inspection
than the electrical bits too.
It proves that he doesn't blindly follow the code, and that he's
willing to learn, and that in the end it's HIS responsibility to make
sure the house is safe, not some book's.
Sure you can. Code says 15 amps, I can wire to 20. I have more
outlets than "every N feet". I have GFIs where they're not strictly
Well - I've heard that John F. Kennedy was assinated by the mafia too.
Sometimes you have to think about the logic of what you hear.
Indeed there is more to a house inspection than electrical, but the
conversation was about wiring. There is nothing more to it than code -
whether that is NEC by default, or local augmentations. But - electrical
inspection is not about some local inspector deciding to inspect based on
what *he* considers safe.
Wrong. And I'll bet his little home cooked test provided no meaningful
data. That "book" happens to be one of the most respected collections of
wisdom known to the electrical world. Any inspector who believes he's
somehow above that should get your worry sense in high gear. In the end, he
didn't accomplish anything to ensure your house or your wire was any safer.
He put on a good show, but where are the results of his tests?
Yeah - a lot of us do that, but I think you know what I was referring to
with my comment. I used a colloquialism.
Your inspector is constrained by the building code adopted by your
jurisdiction. In some states like Florida it is a statewide code with
no local yokel invented rules. They are currently on NEC 2002 and will
be 2005 in July.
It's called a multiwire branch circuit, and it's allowed.
It's allowed primarily because in any box there is never more than 120
line-to-ground, even though there is 240 line-to-line.
The CB which protects a multiwire branch circuit must be a "common
trip" type, so should a 120 side blow, the other 120 side and the 240
Essentially, you wire your boxes as 120/240, using 12/3+G; you tap into
120 alternating black (L) and white (N) then red (L) and white (N), and
so on, from box to box, and if you want 240 in a box then you tap into
black (L1) and red (L2). Wire G as usual.
That's the way I have my shop wired. In fact, I found fixtures that
have one 240 and one 120 outlet. I put one of these and one dual 120
outlet in each box, with the 120 outlet in the 240 fixture on one side
of the circuit, and the 120 fixture on the other side.
But I haven't seen the "common trip" discussion, just assuming that
was how it worked. How can I tell if that is what I have?
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.
I think they're just the common 240V breakers that have an "arm" which
connects the two switches together. That way, if either 120V leg
trips, the other one is automatically tripped as well. I suppose this
would be as opposed to using two 120V breakers in adjacent slots, where
they weren't physically bound together.
Am I right?
2 single pole breakers with a handle tie will not reliably trip the
other side when one side trips.
The 2005 code has addressed that and where common trip is required,
handle ties will not suffice.
A real 2 pole breaker does have internal trip capability that trips
both when one goes.
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