Another Electrical Question, similar to Steve's

I've been following the other thread on 240 and 120 volt circuits on the same line. Is this at all possible, under code?
Let's say I want to add a 240 and 120 line to outlets immediately below my subpanel. I have only two slots left. If I run 12/3 cable (black, red, white, and bare ground), can this be done? The first box would be 240 volt, and use the two hots (black and red), and the bare ground, but NOT the white (neutral). The white (neutral) and one of the hots (black) and the bare ground would continue to the second outlet box, which would result in a 120 volt circuit. Is this code? If so, what do I use for breakers? A double-pole 40 amp, or two separate 20 amps? I realize they must be beside each other, so that the black and red hot wires will be on L1 and L2.
If it is a double-pole 40 amp, could the 120 volt line still trip the breaker if overloaded?
Further, could you run the first 240 volt box (black, red, bare ground), then a 120 volt box (black, white, bare ground), and then another 120 volt box (red, white, bare ground)? What breaker combination would you use then?
I would just run a separate line, but my box is running out of space. I should also add that I assume the 240 volt box would NOT be running at the same time as either 120 volt circuit.
Thanks for any info. I know that, logically, this setup would work. But, is it code, and is it wise?
tt
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I am not an expert, although I did stay at a Holiday Inn Express this summer, so I don't know if the code allows this. And I am not giving advice here, but if'n it was me, I would wire up a stinger box on a short pigtail cable to accomplish that. It ain't hard wirin' so the code nazi's can't get ya, and it'll get ya where you're trying to go. Is it wise? About a million carpenters can't be wrong.
-- Bill Pounds http://www.bill.pounds.net/woodshop

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Yes.
Yes.

None of the above. Use a double-pole 20-amp breaker.

No, it would start a fire first. That's why you *must* use 20-amp breakers to protect #12 wire.

Yes, you can. Same breaker as above: double-pole 20 amp.

It's permitted by Code, as long as you lose the idea of using 40-amp breakers, and stick with the 20-amp breakers that are required for use with #12 wire.
Is it wise? As long as you label everything properly, to indicate that the two 120V receptacles are fed off of the 240V circuit, I don't see a problem there.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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On Sun, 26 Oct 2003 03:16:45 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Thanks Doug. I meant double-pole 20 amp, but thanks for the info and the correction.
tt
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Why not just add some 1/2 height/double, (what ever you call them!), 120 volt breakers on some old circuits, or add a sub panel? seems to be more logical than what you are thinking of! Greg
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On Sat, 25 Oct 2003 23:17:13 -0500, "Greg O"

This is already a subpanel, and even though I could squeeze some tandem breakers in, the panel is only rated for a certain number of circuits.
tt
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Iffy.
a 'double-pole' breaker, of appropriate load rating, is required.
note: 40A requires 8 ga wire.

From a standpoint of theory, "yes", "Code" may say otherwise.
Again, you simply need a double-pole breaker of appropriate amperage.

If you _really_ need 40A @240, adding 120V outlets on the circuit is *DEFINITELY*UNWISE*AND*UNSAFE. Without commenting on 'code' issues.
If you put a 'standard' 120V outlet on, it is only rated for 15A loads. even 'Heavy Duty" ones are only rated for 20A. And they're designed to take *ONLY* wire of appropriate gauge for _that_ load. (e.g. 12 ga. but to be safe for a 40A circuit, the wiring needs to be 8 ga. -- problem!)
Using that material where the breaker won't trip until you have a load "significantly" in excess of 40A is _asking_ for troubles. Like starting a fire, and burning the place down.
Depending on the type of panel you have, you -may- be able to get 'half-slot' breakers. Inspectors tend to 'frown on' them, but they are usually 'technically legal'.
If they're allowed where you are, put a double-pole 240 breaker in the two blank slots, for the 240 outlet. *AND* _replace_ one of the existing breakers with a double 'half-slot' breaker. use 1 half- slot to control the -existing- circuit, and the other half-slot for the new 120V outlet.
The alternative is to put in a sub-panel. Using those last 2 slots for a high-capacity breaker for the feed to the sub-panel. And putting the breakers for the actual 'outlet' circuits' in the sub-panel.
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I haven't seen any actually code that forbids mixing 240v and 120v, but the requirement that it be done in a workman like method might be enough to bounce it. You try to keep circuits as simple as possible, so the next guy doesn't do something stupid. Multiwire circuits are bad enough, but 240v and 120v combined is probably going too far.
I kinda dissagree with the guy who says that inspectors frown on half size breakers. Nothing wrong with them as far as I am aware.
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Naaaah.
Sorry, Wade, but you're waaaay off base here. This is common, and definitely *is* permitted by Code.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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Test Tickle wrote:

If you have a Federal Pacific panel, probably not. :)
--
Michael McIntyre ---- Silvan < snipped-for-privacy@users.sourceforge.net>
Linux fanatic, and certified Geek; registered Linux user #243621
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From my personal experience, even the single pole FPE breakers are bad also.
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I had a FPE box in a house once. An electrican friend told me to not waste money on a welder, just short circuit a wire and go to work.

also.
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I would use the 2 slots to run the 240volt outlet. I would then run the 120volt outlet off of a slot that already feeds 120 volt outlets by replacing the existing breaker with the kind that has two spaces on them (sorry, I can't remember what those breakers are called)
Another option would be to run a subpanel off of this panel
Frank
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I have followed these two threads and they both remind me of what I did and should have done before the electric fire I had. Looking at it in its simplest form what we have in a 240VAC are really two 120VAC's. The diff's lie with the circuit panel whereas mentioned already is the AMP rating. Do not know where you live but local laws apply when you do a job like this so check first otherwise if a electrical fire arises! good luck getting your insurance money. Lets say a rating of 240VAC is 40 amps. However whether you actually get 240VAC is another question by law you must under rate the amp load by 20%, (use Ohms law) next if we take a only a 120VAC leg again amp load is under cut by 20%. Now, since we are relying on the original 240VAC to trip a 120VAC leg it will not happen early enough. Why because the maxium safety amp rating on 120VAC is 30amps with a earth ground copper rod. 20 amps with earth ground galv pipe. We have now created the perfect condition for a electrical fire. However, if and when it strikes is another matter. I used the above approach for a very long time. Then one day when I was gone it happend ELECTRICAL FIRE! no equipment was running at the time. To make a long story short, based upon the insurance and fire department investigation over time the electricity broke down the components and wiring sheaths and shorted. Yea right! but after the fire the only tool untouched was my table saw (110VAC). I took the motor apart and examined the motor windings and brushes. Sure enough I saw evidence of arc's on the windings and severe electrical arc burns on the brushes. Fact or fallacy as the cause or result of using a leg off a 220VAC?
Your guess is good as mine. I can tell you that it took me 9 months to get the Insurance to pay. After which they cancelled my policy. Today, I still use 120VAC legs off a 220VAC but with one big difference. I use a high voltage power distribution transformer. It supplies 220VAC and 120VAC in a safe manner and can turn every light and tool on. Yes, it cost me money about $800.00 but can tell you that the insurance company even gave me a 20% discount on my policy after installing it. My friend also picked one up at a auction for $50.00, twice the capacity of mine.

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I think I understand why you had an electrical fire. Please don't attempt any more electrical work in the future.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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Yeah Doug,
The work was done by an electrican. Had to sign a waiver and he did the job even the city signed off on it with warning. As the city inspector said to me "short cuts lead to short circuits". The hassels with the insurrance and all was not worth the money saved. Do it right the first time or don't do it at all.
The thing that kills me is simply Yes it can be done as everyone has talked about and the city will sign off on it but you just put yourself at a fine line or I should say a fire line! One thing I was told by the Insurrance company that if it was a commercial building the city would have never allowed it in the first place!
Lesson learned: All or any modifications to my home shop and home are done based upon commercial code! Overkill perhaps, but I sleep better at nite.
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