LD1
Epic Contributor
Kinda odd how they will allow a 15A recepticle on a 20A circuit.
That sounds more dangerous than a 20a recepticle on a 15a circuit:confused2:
Adding 220v welding circuit to the shop/garage
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Kinda odd how they will allow a 15A recepticle on a 20A circuit.
That sounds more dangerous than a 20a recepticle on a 15a circuit:confused2:
grsthegreat
Super Star Member
That it does....but its the great NEC cra* shoot i go thru every day..
Sometimes i wonder why i didnt become a plumber
KennyG
Elite Member
The section on receptacles really surprises me. Does the exception referring to 630.11 allow a 50A receptacle on a lighter circuit? (I don't have a code book.) In my experience, it's a really common practice to put 50A receptacles on 30A circuits, pushed in part by welder manufacturers putting those 50A cords on machines that don't require it.
I don't know why they do it, but I don't think you could ever run my Lincoln 180 hard enough to pop a 30A breaker and most people could probably get by with a 20 amp.
I don't know why they do it, but I don't think you could ever run my Lincoln 180 hard enough to pop a 30A breaker and most people could probably get by with a 20 amp.
hr3
Veteran Member
Come on guys,, think about it for a min. If you have a 20a 120 volt circuit with a 15a outlet.. Well this outlet has 2 places to plug in not just one.. say you have 2 .. 8 amp loads you want to plug in,,,, each side of the outlet is rated for 15a.. If everything was wired and torqued properly it should run for a very long time with no problems..
Inspector507
Super Member
Not replying to anyone in particular. The NEC does allow 15A or 20A receptacles on a 20A circuit, provided there are more than 2 or more receptacles on that circuit. No restriction commercial or residential. NEC 210.21(B)(3).
The welder outlet can be supplied with #10AWG wire and protected by a 50A breaker. Look at the Overcurrent Protection for conductors in NEC 630.12(B). The wires can be protected at not more than 200% of the conductor ampacity. Article 240.3 specifically points you to Article 630 for conductors supplying a welder. The ampacity charts in NEC 310 no longer apply.
Enforcing the NEC has been my life for the last 23 years. I've taken flak before for posting the above, but that's OK, I have my appropriate PPE on.......LOL
The welder outlet can be supplied with #10AWG wire and protected by a 50A breaker. Look at the Overcurrent Protection for conductors in NEC 630.12(B). The wires can be protected at not more than 200% of the conductor ampacity. Article 240.3 specifically points you to Article 630 for conductors supplying a welder. The ampacity charts in NEC 310 no longer apply.
Enforcing the NEC has been my life for the last 23 years. I've taken flak before for posting the above, but that's OK, I have my appropriate PPE on.......LOL
grsthegreat
Super Star Member
630.11 just rates the multiplication factor for ark welders based on their duty cycles. .. and this is more or less applicable to multiple welders.
grsthegreat
Super Star Member
yeiks.......#10 MAY be rated for 50 amps ?? where do yo find this little tid bit?
i guess ill have to go buy a 2011 code book. they have just come out at our supply house. Im not due to take classes in the 2011 changes for 3 months.
Ive lived by tables 310....for ever. are you telling me that they no longer are going to be used???
And what about the caveat that stated that #14 shall not exceed 15 amps, #12 not exceed 20 amps and #10 not exceed 30 amps...EVER, no matter what the temperature.
210.21 that i posted earlier stated the info about the 15 amp recepticle on a 20 amp circuit.
Personally, i wish they did away with the entire code book.
as i've stated a few times, i'm not a professional, so my answer may not have the proper terminology, but the theory behind it should be correct. this isn't some new regulation, it's been there for some time. it is based solely on the circuit being used for a welder (duty cycle driven machine).
we all know that when a breaker sees a load in excess of its capacity, it trips instantly. when a wire sees an excessive load it does not instantly melt and burn the house down. it slowly heats up, and if the load is applied for too long, failure could then occur. since welders have a duty cycle - homeowner sized machines often have duty cycles of 20%-40%, meaning that in a given 10 minute period, the welder can only draw that maximum load for 2 to 4 minutes. because of this, the wire that is overstressed can cool down safely before the load is applied again. there is a calculation to determine how much you can undersize the wire by. i'm sure the previous poster can provide a link, and can probably explain it better than my layman's attempt.
dstig1
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Well think about it this way - you plug in a lamp to that 15 or 20A outlet. The lamp has 18 ga cord (pretty common). 18 ga isn't rated for even close to 15A, much less 20A so how is that allowed? For single family residential outlets, the code allows you some leeway with 15 & 20 A outlets, mostly as a convenience, IMHO. It allows you more flexibility to wire outlets on a 20A circuit for less breaker tripping potential, without requiring the 20A plug. An actual 20a 120V plug is pretty rare, but I have seen them a couple times in my life.
grsthegreat
Super Star Member
there not rare, just expensive. There called spec grade recepticles, and we use them on commercial jobs. There in the $6-8.00 range. But at least they dont have that crappy tamper resistance rating that i truly hate.
Anyone that allows those TR outlets to remain in their homes is a NUT IMHO....for what its worth. Stupid codes require all 110 outlets in residential to be tamper resistant, but NOT 220 outlets. 220 will KILL a kid, 110 will just shock them and make them think twice about doing it again.