Junkman
Super Member
Don't forget AndyMA.... he is an electrical engineer.... but I am not sure if that means that he knows how to operate electric trains
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Wiring 220V compressor
- Thread starter Volksfolks
- Start date
- Views: 6759
TWINKLE_TOES
Veteran Member
- Joined
- Sep 3, 2000
- Messages
- 1,366
Whoops, should have said <font color="blue"> we need another good electrician </font> No offense intended to the other electricians. BTW Mike who did I miss?
CTyler
Veteran Member
Hello...
Yea I get a little touchy sometimes and here's a brief on why.
There were several things assumed. He talked to the"Expert" at Home Depot. Now I don't know if he meant that as a joke or not. Some folks there are knowledgeable others are not. I assumed that the "Expert" gave him some advise and he wanted to confirm the wiring. I also assumed some very basic electrical knowledge. I then went stated in a another post how to do it safely and what is typically done. Then your post comes along lamb basting everything.
I have nothing against people preaching safety. I try to make it a habbit of asking "Is what I am doing safe?".
I'm not P.O.ed or anything, just needed to clear the air is all.
Have a good day.
Chris
Yea I get a little touchy sometimes and here's a brief on why.
There were several things assumed. He talked to the"Expert" at Home Depot. Now I don't know if he meant that as a joke or not. Some folks there are knowledgeable others are not. I assumed that the "Expert" gave him some advise and he wanted to confirm the wiring. I also assumed some very basic electrical knowledge. I then went stated in a another post how to do it safely and what is typically done. Then your post comes along lamb basting everything.
I have nothing against people preaching safety. I try to make it a habbit of asking "Is what I am doing safe?".
I'm not P.O.ed or anything, just needed to clear the air is all.
Have a good day.
Chris
bxbuster
Bronze Member
This is an interesting thread. I guess you learn something everyday. So, if I read this right, it is illegal to use a plug that is over rated for the circuit? I cannot put a 20 amp outlet on a 15 amp circuit? How about a 20 amp switch on a 15 amp circuit? I have never heard of this. Thanks for the information!
bxbuster
Bronze Member
Interesting enough it appears that to be code compliant you can install a 50 amp outlet with a <font color="red"> </font> 50 amp breaker and use only a <font color="red"> </font> 10 gauge wire if the outlet is to be used by a welder? /forums/images/graemlins/shocked.gif If you want to read it for yourself, it is pages 785 to 788 of the 1999 National Electrical Code book. The NEC is written by the National Fire Protection Association. I believe that they know what they are doing!!!
Thanks again for all contributors to this thread.
Thanks again for all contributors to this thread.
johnbilt
Silver Member
Hi
Section 630 of the NEC is for Electric Welders. I checked my 1999 copy and see that they allow a calculation based on duty cycle to determine an adequate supply wire size. I don't see where it specifies a #10 conductor as stated above. Perhaps there is another reference in a separate section.
I suppose that this could apply to a plant setup where multiple welders are being used.
But why would I derate my own shop setup, and introduce a significant voltage drop ?? Just to save $10 in wire ?? I use #6, rated at the full 50A service, with the proper grounds. It works great and I sleep well at night !!
Just my opinion /forums/images/graemlins/cool.gif
John
Section 630 of the NEC is for Electric Welders. I checked my 1999 copy and see that they allow a calculation based on duty cycle to determine an adequate supply wire size. I don't see where it specifies a #10 conductor as stated above. Perhaps there is another reference in a separate section.
I suppose that this could apply to a plant setup where multiple welders are being used.
But why would I derate my own shop setup, and introduce a significant voltage drop ?? Just to save $10 in wire ?? I use #6, rated at the full 50A service, with the proper grounds. It works great and I sleep well at night !!
Just my opinion /forums/images/graemlins/cool.gif
John
fractal
Gold Member
</font><font color="blue" class="small">( My compressor only has places for 3 wires. I was told by the "expert" at Home Depot to wire the green and white wires together and put them on the green spade.)</font>
That expert is wrong. Very wrong.
The white (neutral in the us) and green wire (ground in us) should be connected one place and only one place and that is at the service entrance panel.
I am not an electrician but I seem to recall the NEC specifically prohibiting using dual mode 120/240 outlets for 240 only appliances. I have no clue why, but I have been told that it is prohibited.
If you want to do it right, then I would suggest the same thing that the others have recommended, running a dedicated 240/15 or 240/20 outlet for the compressor.
On the other hand, let's remember who wrote the NEC and what its job is. It was written by firemen who don't want to see your house go up in smoke. The 30 amp circuit breaker on your dryer circuit is there to protect the wiring inside the wall to ensure it does not overheat and catch fire. Honestly, it is. That circuit breaker is not there to protect your appliances. It is there to protect the wiring and connectors. Connecting a 15 amp appliance to a 30 amp circuit "should" present no hazard. After all, how many of us plug in lamps wired with 18 guage wire (rated at about 6 amps) into a 20 amp standard wall outlet? You put a partial short in the lamp and the wire / plug will melt before the circuit breaker pops..
That expert is wrong. Very wrong.
The white (neutral in the us) and green wire (ground in us) should be connected one place and only one place and that is at the service entrance panel.
I am not an electrician but I seem to recall the NEC specifically prohibiting using dual mode 120/240 outlets for 240 only appliances. I have no clue why, but I have been told that it is prohibited.
If you want to do it right, then I would suggest the same thing that the others have recommended, running a dedicated 240/15 or 240/20 outlet for the compressor.
On the other hand, let's remember who wrote the NEC and what its job is. It was written by firemen who don't want to see your house go up in smoke. The 30 amp circuit breaker on your dryer circuit is there to protect the wiring inside the wall to ensure it does not overheat and catch fire. Honestly, it is. That circuit breaker is not there to protect your appliances. It is there to protect the wiring and connectors. Connecting a 15 amp appliance to a 30 amp circuit "should" present no hazard. After all, how many of us plug in lamps wired with 18 guage wire (rated at about 6 amps) into a 20 amp standard wall outlet? You put a partial short in the lamp and the wire / plug will melt before the circuit breaker pops..
