Adding 220v welding circuit to the shop/garage

[bky]

. 220 will KILL a kid, 110 will just shock them and make them think twice about doing it again.

OK I hate to get on a soap box. I hear this statement all the time. (it bothers the heck out of me) current kills weather it's 220 or 110 volts.

sorry i cant help it.

 

[tshep]

grs - you memorized a good rule, just not all of it!

310.16 *'s take you to 240.4 D, which basically says general purpose (non-exception) circuits are as you know.

BUT special circuits can be otherwise - 240.4 E through G.

For instance, I do heat pumps that call for smaller wires on bigger breakers - say #14 on a 20 or 25. Seems to be against the rules.
But, the idea is that UL has tested the failure modes for certain devices and they are such that the conductor will not fail with that size breaker protecting the circuit for startup time, for instance. If it is locked up, it's a short enough time yet such a big overload rate that the breaker will still trip long before the wire gets hot. The difference between load and overload is inherently greater than just one too many toasters!

The supply breaker, the conductor, and the specific load are all part of the system. Different loads act in different ways - and may have exceptions.


Another thought, for all, is not to just look at conductor cost if you are the one paying the electric bill. If there is some real chance you may actually spend some real amount of time paying to flow near max amps of electricity through that minimum size conductor - buy a bigger conductor made of copper, or you are just paying to heat up dirt, or your garage or worse - and maybe then paying again to aircondition that heat back out. All those ohms that make that conductor voltage drop multiply out to watts that convert directly to BTU's of heat. I can garantee you tommorow's electricty is gonna' cost more than today's copper!
Most electricians get into bidding habits, and then miss opportunities to save operating costs in their own systems.

 

[dstig1]

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.

Note I said 20 a PLUGS are rare, not receptacles. I have only seen 2 things in my life with a 20A/120V plug on it, and one was a high powered industrial heat gun. I've seen plenty of 20A/220V plugs, and plenty of 20A/120V Receptacles...

I am unfamiliar with the TR outlets you are referring to. Something new in the code???

 

[ssmith general]

OK I hate to get on a soap box. I hear this statement all the time. (it bothers the heck out of me) current kills weather it's 220 or 110 volts.

sorry i cant help it.

It's the amps that kill.

 

[not2old]

My small mig welder is a Miller that has an input of 20amps, 120 volts with a 15 amp plug from the factory. I've occasionally used it on a 15 amp circuit until the breaker trips repeatedly. Awhile after I plug it into a different circuit, the welder's internal breaker will trip before the next panel breaker trips. I'm told this shouldn't happen, but it has done so at several different places I've used the welder. Breakers and wire must both heat up, wether or not the load is at the maximum or not.

 

[grsthegreat]

Note I said 20 a PLUGS are rare, not receptacles. I have only seen 2 things in my life with a 20A/120V plug on it, and one was a high powered industrial heat gun. I've seen plenty of 20A/220V plugs, and plenty of 20A/120V Receptacles...

I am unfamiliar with the TR outlets you are referring to. Something new in the code???

TR receptacles are tamper resistant receptacles. they were new last code revision (2008). They suck, and i get nothing but complaints from homeowners about them.

they have a little trap door behind both openings that will not allow anything to be inserted into it unless something is inserted into both openings at the same time. and the black receptacles with the white TR doors (since all TR receptacles use the white colored interior covers) are not very attractive.

also, i realize that current kill, but Ive been shocked with 110, but Ive been thrown for a loop with 220. If there going to pass a law requiring TR receptacles for 110, it should also be passed for 220. thats all I'm saying. there are too many ambiguities in the code.

 

[dstig1]

Oh goody. Sounds like something that gets swapped out the moment the inspector signs off... I haven't heard about them around here, but we may not be on NEC2008 here yet. I need to check into that...

Edit - just checked and they adopted 2008 in early '09. Ah well...

 

[Inspector507]

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.

Actually if you use 90C wire it could possibly go as high as 80A. 200% of 40A is 80. But I wouldn't do it.


If you look at the text of NEC 240.3 it says:
240.3 Other Articles. Equipment shall be protected against overcurrent in accordance with the article in this Code that covers the type of equipment specified in Table 240.3. Copyright NFPA
Then look at Table 240.3. Under Welders or Electric welders I forget which it directs you to Article 630. That is out of the 2008 NEC, not 2011. We don't enforce that yet until maybe Jan 2012.

edit.........just checked the 2011 NEC. It's still the same.

 

[grsthegreat]

Actually if you use 90C wire it could possibly go as high as 80A. 200% of 40A is 80. But I wouldn't do it.


If you look at the text of NEC 240.3 it says:
240.3 Other Articles. Equipment shall be protected against overcurrent in accordance with the article in this Code that covers the type of equipment specified in Table 240.3. Copyright NFPA
Then look at Table 240.3. Under Welders or Electric welders I forget which it directs you to Article 630. That is out of the 2008 NEC, not 2011. We don't enforce that yet until maybe Jan 2012.

edit.........just checked the 2011 NEC. It's still the same.

the only thing i know for sure anymopre....is the inspectors only allow us to use the 60 centigrade tables anymore for our load calcs..been that way here for about 6 years (2 code cycles)

 

[Inspector507]

is the inspectors only allow us to use the 60 centigrade tables anymore for our load calcs

As you can see, there are more ways to apply ampacity limits than just 310.16. Just depends on your application. On 100A or less you use the 60C column. On over 100A you use the 75C column. For derating you use the 90C column if you have 90C rated conductors.

Well......
Unless all your terminals are rated higher
Unless it's a wet location
Unless it's in thermal insulation
Unless..........

There are so many exceptions in the NEC it's mind boggling.

 

[SixHoeBob]

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.

ARK welders - I thought Noah used wooden pegs and maybe nails.

 

[grsthegreat]

ARK welders - I thought Noah used wooden pegs and maybe nails.

ya well......ARC

happy now LOLOL:laughing: :laughing: :laughing: :laughing:

 

[SixHoeBob]

OK I hate to get on a soap box. I hear this statement all the time. (it bothers the heck out of me) current kills weather it's 220 or 110 volts.

sorry i cant help it.

I was absent from school this day, so I missed the excitement.

Eleventh grade science class... One of the students (reasonably intelligent male) was bored while listening to the teacher. After a while the situation developed where he put one end of a generic staple into a 110V outlet at his lab table. The other end touched the metal cover. Instant heating element, that burned a path in his finger and thumb. He learned that day to respect electricity. In fact, the whole class might still remember that lesson.
Tolerable pain is a good teacher.:thumbsup: And yes, Weather and 110 can be a bad combination.

 

[grsthegreat]

there making everything so child proof...even adults cant use it.

wait till theres a batch of kids that have never been exposed to any dangers growing up...suddenly travel to another country or?? and find something thats not child proofed, BAM.

Were just dumbing down generations of kids. Its truly amazing that i was able to live this long without safety helmets on bikes in school, without seat belts in my parents car, playing with electric outlets, rebuilding toasters, pulling bullets apart to get to the gun powder.....heck i used to have a 30-30 winchester in the gun rack of my truck while attending college in Calif back in the 1970's. (id be labeled a terrorist now daze).

 

[crazyal]

I love how a simple question "I'm going to get a quote from an electrician but before I do where should I mount an outlet for a welder?" (not exact words but sums it up nicely) has turned into a lesson on codes.

To Nickel if you haven't done it yet I would future plan. I would have the electrician wire up an outlet for a NEMA 6-50 outlet. It may be a little overkill but you can always change the plug on your welder and if you ever upgrade or buy a plasma cutter you'll be all set. Secondly I would think about adding a second outlet for an air compressor (I don't remember reading that you have one). I doubt it'll add too much to the cost.

 

[beppington]

It's the amps that kill.

I've only ever seen High Voltage signs, not High Amperage signs ...?

 

[Mace Canute]

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.

I suspect that the reason for TR 120V receptacles is because they are so much more common and easily accessible in residential. I have only two 240V receptacles in my house, the dryer and the stove. The stove's is inaccessible without moving the stove and the dryer's is very hard for a small child to reach...about 4 feet above the basement floor and behind the dryer...whereas there are many many easy to reach 120V receptacles throughout the house.

As far as which voltage is "safer"...one killing and one just shocking...well, that statement is absolutely incorrect. ( A little FYI...the UK has fewer deaths per capita by electrocution than the USA and yet they use 240V in residential. ) It is very difficult to get a 240V shock from a properly installed receptacle since you have to contact BOTH hotlegs at the same time...if you touch just one hot leg and get a shock, it's a 120V shock and it's to ground. I've had a 240V shock and it HURTS!!! :shocked:Cracked insulation on a 480V between hot legs/240V to ground undergound streetlight cable, eh.

 

[Mace Canute]

I've only ever seen High Voltage signs, not High Amperage signs ...?

The voltage (difference of potential) is what drives the current and the current is what does the damage. If you scuff across a rug, you can charge your body to several thousand volts and yet you are unharmed when it discharges in a small spark since there is such a minuscule amount of current involved with the static charge. A larger static charge might very well have enough amperage available to injury or even kill you...lightening being the most common example of this. From Lightning "The average lightning stroke has a peak current on the order of 30,000 amps. But some discharges, especially those that are totally within the cloud, are only several thousand amps. On the other hand, superbolts do occur, occasionally reaching 300,000 amps or more. The electrical potentials involved in lightning discharges can range up to 200 million volts."

Anytime you see a high voltage sign, trust that there is enough amperage available to cause you injury and /or death. According to the 2002 National Technology Transfer's manual, Electrical Safety Requirements and Procedures, the average male can perceive electrical flow from 1 milli-ampere (mA - also called milliamps) - 10 mA (0.001 amps - 0.010 amps). From 3 - 10 mA the sensation is very painful. At 10 mA is the paralysis threshold, where you can't release your hand grip on an object. At 30 mA (0.030 amps) is the respiratory threshold which causes a stoppage of breathing and can be fatal. At 75 mA (0.075 amps) is the fibrillation threshold where heart action is discoordinated. Fibrillation can not be treated with CPR and at this state it can be fatal if a defibriillator is not applied within several minutes. Typically, the thresholds for women are slightly less.

 

[beppington]

The voltage (difference of potential) is what drives the current and the current is what does the damage. If you scuff across a rug, you can charge your body to several thousand volts and yet you are unharmed when it discharges in a small spark since there is such a minuscule amount of current involved with the static charge. A larger static charge might very well have enough amperage available to injury or even kill you...lightening being the most common example of this. From Lightning "The average lightning stroke has a peak current on the order of 30,000 amps. But some discharges, especially those that are totally within the cloud, are only several thousand amps. On the other hand, superbolts do occur, occasionally reaching 300,000 amps or more. The electrical potentials involved in lightning discharges can range up to 200 million volts."

Anytime you see a high voltage sign, trust that there is enough amperage available to cause you injury and /or death. According to the 2002 National Technology Transfer's manual, Electrical Safety Requirements and Procedures, the average male can perceive electrical flow from 1 milli-ampere (mA - also called milliamps) - 10 mA (0.001 amps - 0.010 amps). From 3 - 10 mA the sensation is very painful. At 10 mA is the paralysis threshold, where you can't release your hand grip on an object. At 30 mA (0.030 amps) is the respiratory threshold which causes a stoppage of breathing and can be fatal. At 75 mA (0.075 amps) is the fibrillation threshold where heart action is discoordinated. Fibrillation can not be treated with CPR and at this state it can be fatal if a defibriillator is not applied within several minutes. Typically, the thresholds for women are slightly less.

OK, I get all that - Just curious why High Voltage was chosen as the warning sign over High Amperage ...

 

[crazyal]

OK, I get all that - Just curious why High Voltage was chosen as the warning sign over High Amperage ...

Voltage is what jumps. A spark plug works because of high voltage, lightning strikes because of high voltage. The simple fact is voltage and amps are tied together.

Just saying it's the amps that kill you is only sort of true. For the amps to kill you it must get to your heart. The human body has a fixed resistance, you can drop it when you wet your skin, but let's assume you are not stingin knee deep in water in the pouring rain working on an AC panel.

If you have ever heard of ohm's law you know that V(volts)=I(amps)xR(resistance). If the resistance stays the same and you increase the voltage then you decrease the amps needed. And like Mace pointed out it only takes a small amount of current, 75mA to kill, if it reaches your heart. I avoided the effects of frequency to simplify things.

In the real world when ever you see that sign it means that high voltage and high current, beware.