Steve Sells,
I am sorry if I took your comments as an attack but the posting seemed to me to be very emotionally laden and accussing me of being an amature, not knowing what I was doing.
Facts and errors can and should be comunicated, However high emotional content often clouds the meassage.
I am currently hospitalized and I was going by memory as I did not bring my NEC code book to the hospital with me and I did not remember the exact exceptions.
I now remember the basic contents of 240.4 after reading your reply and I admit that 240.4 limits a #12 Copper conductor to 20 amp overcurrent protection in most situations.
So in most situations your are correct on the NEC (National Electric Code) limit of 20 amps, but this is based on reasons other than the amp carrying capacity of the wire.
However their are mutiple exceptions addressed in 240.4 that allow more than 20 amps for #12 Copper conductor so your comment that the NEC never allows more than 20 amps is not accurate. In wiring a house are you are correct.
But the entry of 25 amps as an allowable ampacity in table 310.16 clearly means that #12 copper with THHN wiring is good for 25 amps without the damage of overheating of the wire or the insulatation when used as indicated. (no more than 3 current carrying conductors in raceway or cable etc).
Do you agree that the ampacities listed in table 310.16 are the ampacities so that the conductors will not overheat and damage the insulation?
I was simply observing that a #12 can safely carry 25 amps which is true. Simple math would further indicate that if you were to desire to run parrallel #12 romex cables that they would carry 50 amps without overheating or burning but I clearly stated that this would be CONTRARY to the NEC. This was in the context of a "cable assembly" to power a welder when not near an outlet, not as permanent wiring, if you reread my original posting.
I don't want to get in to a nitpicking mode here, but table 310.16 states the allowable amp carrying capacity of the the conductor and does not provide the information required for voltage drop calculations. This information is elsewhere in the Code.(near the back of code if I remember correctly with tables of Ohms values for the conductors and Impeadance for wire and raceway assemblies, again I don't have my NEC book with me)
I understand your somewhat porochial view of electrical wiring systems and the NEC code. This has been a key message of the Union to which you are a member. And in general my expereince is Union electricians are better trained and provide better work than most others.
But what do we do with mechanical codes and trained mechanical trade techicians?
The balance of the NFPA (National Fire Protection Association) of which NEC is only one section, is generally as applicable in the most local governemental jurisdications as the NEC. The alternate name for the NEC is NFPA 70
Is your forge a portable forge that is only operated outside your blacksmith shop? If not, it most like a fuel burning appliance whose "installation" must be in compliance with the all provisions of the NFPA codes. Further most goverment authorities will insist that fuel burning appliances be listed by the UL (Underwriters Lab), ETLM (Energy Testing Lab of Maine) or CSA (Candian Standards Association). If it is a gas burning appliance then it must be a tested and listed by the AGA (American Gas Association)
As I have previously indicated nearly everytime we fire up our forge we violate the Mechanical Codes which are just as important or in some cases more important than the NEC.
But I will admit that most inspectors will "wink" at a forge installation if basically safe as they don't want the hassle digging thru all requirements and most appreciate at some level the craft we are involved in.
We as blacksmiths are somewhat a fish out of water and would fit in better to our society 100 years ago than in today's highly regulated enviroment.
Bottom Line: We must understand the risks, manage the risks and behave appropriately. If we do not understand the risks we should not play.
Keep Forging!
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