Over in Knots (Finewoodworking) there’s a thread that deals with stealing 220 volts from a dryer circuit (30 amps) to supply an outlet box for a 220 volt cabinet saw. In my view, this is not code but I’m curious as to what the folks here think.
He evidently has his connection in a J-box, and has run #10 wire to the new outlet box. But I don’t think this is code.
Clearly, the guy didn’t get a permit but that’s another topic. Opinions?
John
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Replies
Here where I live, we can do the work ourselves, no codes, permits,
etc.
You can run into trouble selling later if you haveen't met all the
standard codes.
I always follow the national codes for safety anyway.
Commercial is different though.
Jeff
Thanks. I didn't realize there were places where residential wiring could be done sans permits.
In your opinion, would the wiring in question be done according to code?
John
I'm no expert.
But, I think your ok.
Jeff
Thanks. I appreciate the input.
But the purpose of posting here in Breaktime was to get a real opinion about the correctness of all of this. Will it work? Probably. Is it code? I really don't think so. And I also think that having the 30 amp breaker for a saw that is 3 HP is over-fusing it, which is a separate problem.
John
The fuse or breaker is not there to protect the saw or the dryer. It is there to protect the wireing of that particular circuite!
A 3hp table saw at 220v is commonly placed on a 20 amp circuite (#12 wire). Hopefully the saw motor is thermally protected so that it will trip itself out befor it is toast.
If he is sharing a circuit (wire & breaker) with the dryer it is not smart, no matter what combination of wires he is using. My code book is at work, or I would site the section prohibiting this in residential wireing.
Maybe 4Lorn or IBEW Barry will jump in here and qoute you chapter and verse.
Dave
Thanks very much.
He's continued the #10 wire to a receptacle for the saw, so he's not only sharing the circuit with the dryer he's (IMO) over-fused the portion of the circuit for the saw.
John
Hello
In older codes the range and dryer circuit were permitted to use the neutral conductor as an equipment ground if the circuit originated at the service entrance equipment (not a sub-panel). This conductor is white or gray. Given the saw is 220v only, not 120/240, (doesn't need any 120 voltage) the procedure would be to strip the insulation off the white (at least six inches) leaving it bare or taping it with green tape at the receptacle and at the service box. You would then have a legal 220v 30 amp circuit if you use a receptacle that is 220v, 30 amp. The neutral has become your equipment ground.
You no longer have a legal dryer circuit
Modern dryer circuits by code have an equipment ground thus they are 4 wire. Here you would change from the 120/240v receptacle to a 220v only and abandon the neutral.
Again no longer a dryer circuit.
Must be a very large saw. If not, than under fault, the circuit is to large to properly protect the saw , so we need to fuse it down.
Butch
Here's a question I have to ask. What exactly is the safety issue here? I understand that it's not code, but if I hooked up inside the dryer outlet, used the same gage wire to run to a 220 saw, everything would still be grounded and if I tried to run the dryer and the saw at the same time the fuse would trip. How exactly is the neutral a problem?
To answer this , first look at your dryer outlet and tell me the number tine slots. It will be either 3 or 4 , depending on the year the dryer circuit was installed. From there I can simplify the answer.
The saftey issue will be on how we get the frame of the saw grounded.
Butch
I see no problem using the power for the saw and letting the wife and kids use the clothes line.<g>
Ive done it temporarily, but both running together no. Not code. Each needs a dedicated circuit.
Tim Mooney
(Someone tell me a polite way for me to tell my wife to shut-up so I can post a response. Sorry the summary is with yapping in my ear.)
Code has changed no longer permitting an uninsulated conductor to act as a combined grounded conductor (neutral) and equipment ground. I don't know the NFPA's specific reasoning but can't see a technical reason why the change was made. It has worked for the 20 years I've been in the business.
Nevertheless, as far as tapping from the dryer circuit to serve a saw, technically it will work just fine as long as the wiring extension is the same as the dryer circuit (overcurrent protection of conductors meet Code). Although I doubt it is per Code since both the dryer and saw could work at the same time thereby subjecting a load on the branch circuit that would exceed the permitted rating. Consider that a typical electric dryer is rated 4.5 kW and draws 19 amps. This value needs to be increased by 125% per Code to yield a 23 amp effective load. This leaves 7 amps for a saw (if in fact Code permits, I'd have to check) but motors also need a 125% minimum factor applied per Code. These factors account for added heating due to continuous loading and increased heating due to higher inrush of motors. This would permit a maximum saw amperage of 5.6 amps but again, I would need to look into this further.
If you upset your wife and then she starts to nag you, Then you p i s s her off and she gives you the silent treatment, Would it not be worth the extra effort every time?
No other reason to post but that deep thought for the day.I'm all here....... 'cause I'm not all there!