240 VAC Wiring

John T · Jul 19, 2014

WOW, a lot of Misinformation below, in my professional opinion that is. I'm only here to HELP not fight, so to try and help, I with all due respect, submit the following for your consideration to take or leave at your own choice and peril NO WARRANTY DO NOT take my word for, consult the NEC or trained professionals or experts (or risk your life and home on what non profession non trained Billy Bob and Bubba may have to say) BUT I BET WHATS BELOW IS IN AGREEMENT WITH NEC ??? Any takers???

It can be perfectly safe, engineering proper, and NEC permissible to use 14 gauge wire for 240 VAC loads. PROVIDED THAT:

1) The voltage withstand rating (insulation integrity) exceeds the applied voltage potential and the wire typically could be say 600 VAC rated, and if such could be used on 120 or 240 or even 480 volts. NOT 120 ONLY AS SOME THINK in my professional opinion that is.

2) The branch circuit is protected by an overcurrent protection device (fuse or circuit breaker) of 15 amps. This assumes the ampacity of wire is 15 amps.

3) The maximum sustained continuous load does not exceed 12 amps (The 80% rule, 15 x 0.8 = 12)

Where do people get the idea you cant use 14 gauge wire for a 240 volt load??????? They must be confusing or do not understand the difference in a wires AMPACITY (how much current it can safely carry without overheating or damaging the insulation) versus the voltage withstand rating (insulation strength and integrity)

You could have even a 480 volt (TWICE 240) motor that requires less then 12 amps continuous served by wire that has a 600 volt rating and is 14 gauge.

14 Gauge wire IS NOT FOR 120 ONLY, that's NOT my opinion, its the wires current and voltage withstand rating.

Oh well, best wishes and God Bless yall

John T Retired Electrical Engineer so NO Warranty, its been a while, but the basics sort of stick with a guy ya know. Its your own life at risk, so do as yall please, you wont get a fight from me lol

Geo-TH,In · Jul 19, 2014

If Bubba and Billy Bob did some work for you and someone you know was killed or seriously injured, don't forget to call the law firm of DOWEE, Cheatam, and How. 1-800-BAD-WIRE for your part of a class action settlement.

No official wants to go after the Bad Boys and protect us like DOWEE, Cheatam, and How.

JohnT,
Just adding a little humor to your post.
George

John T · Jul 19, 2014

George, Ive heard of that law firm before, but they added one more partner ya know, its now:

Boyd, Dewey, Cheatem and Howe lol

John T Only a Country Lawyer ya know

Greg K · Jul 19, 2014

Its kind of humerous when I hear people tell me that "hey, I've got some 220 wire". I hear that line on a regular basis. Usually I just smile and go along with it unless they ask if that is accurate. That's one of those times where there is a fine line between being helpful and being a know-it-all. Keep up the good work John T.

Mark - IN. · Jul 19, 2014

From my perspective, wire is rated for current, generally not to excede 600 volts. Why voltage has to do with anything, I don't know. At the museum of Science and Industry, there is a glass ball that one can touch that somehow has a million (1,000,000) volts, static no doubt, that one can touch...million volts at minimal amperage, not get killed, burned, but may get an erection (they didn't say that, I just added it). Every wire guide that I've ever seen is based or rated on current.

Since we are on the subject of voltage being constant, current flows...lightning? A bolt of lightning that flows from the more negative to the more positive, and in this exercise involves a ground or tree strike...the bolt of lightning actually flows from the sky towards ground, or ground towards the sky? I know the answer, although my eyes don't really.

Mark

massey 333 · Jul 19, 2014

Greg,That can be true on the 220 wire statement,if someone would go in and ask for wire for a 220 useage,they would be given 3 plus gr.wire and not 2 plus gr.even tho either will work fine on 220.So that statement isn't untrue or dumb.

john in la · Jul 19, 2014

I always considered the whole reason for going 240 volt was so you could use smaller wire.

A well pump is a great example.
A 1hp Gould is rated at 16.2/8.1 amps
To get 8.1 amps at 100 feet 14 gauge will work.
But to get 16.2 amps at 100 feet you need to use 8 gauge wire.

But here is a question for you........

You use the chart to size wire for a sub panel such as in a shed or pump house.
Lets use the example of 120 feet run 12 gauge wire protected by a 15 amp breaker at the main panel.
If you break the legs at the sub panel to provide a 110 plug for a light or to run a small power tool are you now out of line because of the voltage drop.

FLOLDFORD · Jul 19, 2014

John T
Remind me to pay you your retainer when you get to Florida this winter. Hate being without a lawyer good or bad

Gary

David G · Jul 19, 2014

John,

I would like to add to your clarification. Wire size determines ampacity, insulation rating determines maximum voltage that it can carry.

buickanddeere · Jul 19, 2014

(quoted from post at 09:42:32 07/19/14) Greg,That can be true on the 220 wire statement,if someone would go in and ask for wire for a 220 useage,they would be given 3 plus gr.wire and not 2 plus gr.even tho either will work fine on 220.So that statement isn't untrue or dumb.

Wrong . Why is 14/3 required to use 240volt?

John T · Jul 19, 2014

I will hold you to that Gary, hope to see you there...........

John T

El Toro · Jul 19, 2014

You also need to figure distance. My AC and air compressor are wired with #10. That was in 1970
when I wired them. Hal

John T · Jul 19, 2014

David, Good point, and the two (wire size PLUS insulation) are related as I was taught years ago. Here's my more complete take on it now that you brought it up as I best recall, but that was yearssssssssss ago lol so again NO WARRANTY.

You could rate a stand alone bare wires ampacity considering how much current it can carry BEFORE it might heat to the point it looses mechanical strength or integrity or a certain degree of conductivity.

NEXT when you encase it with insulation, the insulating materials (such as a THHN thermoplastic) design and quality has a certain rating such as how much current the enclosed wire can carry BEFORE the insulation degrades or deteriorates and at what current is there enough heat generated which could degrade or overheat or melt the insulation.

I see it takes BOTH wire size and wire type PLUS the physical and chemical characteristics of the insulation all coupled together to achieve a final "ampacity" rating. If you have No 6 bare copper wire in air it may have a higher ampacity rating then if it were covered with a thermoplastic insulation which heats up the more current the inner wire carries, therefore if insulated you may not be able to conduct quite as much current because you have to consider the chemical property of the insulation and how much heat before it degrades.

If you look at NEC ampacity charts, there are columns based on ambient temp,,,,,,,,, type of insulation (like THHN),,,,,,,,,,,,if enclosed,,,,,,,,,,,,if in free air or if buried or how may conductors inside a conduit etc etc SO I SEE IT AS WIRE SIZE PLUS INSULATION PLUS SURROUNDINGS ALLLLLLLLLLLLLL WHICH DETERMINE AMPACITY

That all has to do with current. The max voltage rating has to do with the insulation such as the type and thickness and wire spacing etc etc.

very fun chattin with you

John T

John T · Jul 19, 2014

EXACTLY The AMPACITY concerns the wires current rating while VOLTAGE DROP is also a consideration when computing wire size that should be used. However, to my intended point, theres still no reason why 14 gauge 600 volt rated wire cant be used for 240 or even 480 volt branch circuits. Then after you consider sufficient ampacity take a look at voltage drop to see if a larger gauge is required.

Very fun chattin with you Hal

John T

Anonymous-0 · Jul 19, 2014

I don't get your remark B&D,you only need 2 plus ground for 240 only.But if someone goes(asks) to buy wire for a 240 job(need),99% chance they will be given a 4 conductor wire(which is what I said).

John T · Jul 19, 2014

Hey Massey Man, I owned a Massey 333 and loved it, wish I still had it grrrrrrrrrr

I have a question regarding your statement "if someone would go in and ask for wire for a 220 useage,they would be given 3 plus gr.wire and not 2 plus gr."

If a person indeed asks for a wire for 220 useage (NOT 110 PLUS 220) why would he need or be given 3 plus ground???????????????????? If its indeed 240 VAC Single Phase (NO 120 involved) THREE wires suffice, 2 insulated conductors PLUS an Equipment GroundING Conductor. That's ONLY 2 plus Ground. SURE if he just had to have or wants to buy 3, 4 or even 5 conductors it will still work, just wonder why he needs more then three wires (2 Hots & Ground)???

Not wanting to start a fight or argue remember Im here to help NOT fight, just asking as I figure Im never to old to learn

John T

TomH in PA · Jul 19, 2014

Many students slept through physics when volts, amps, and watts were explained. More power must mean you need a bigger wire, right?

On a slightly related note, last week I listened to a couple of my cousins arguing that students should be taught how to calculate flux - because the concept and formulas are really the same whether you"re talking about flowing electricity, heat, water, whatever.

David G · Jul 19, 2014

Agreed,

That is why there are conduit fill and other requirements. I usually deal with 2 insulation levels, 600V for up to 480VAC and 300V for communications.

This brings up an interesting topic. Motor starters have been available with Ethernet connections for a couple of years now. We were installing them in MCC sections that should have had all 600V wire, but used 300V Ethernet cable. Typical Ethernet cabling has a 300V rating, but you can now get it with 600V rating. It took a little while for the wire manufacturers to catch up.

John T · Jul 19, 2014

That word FLUX always made me nervous lol. I had a Prof once at Purdue EE school who proclaimed if you burned every book in the world but one, the one you saved should be MAXWELLS EQUATIONS. He was really into that. When we studied "Electronics of Solids" it involved quantum mechanics and Maxwells equations and all that complicated physics, I barely got a passing grade, it was the hardest subject I took

John T

big fred · Jul 19, 2014

John, when I hear "flux" I think of cosmic ray (neutron) flux, but that's just me, having had to consider it in my job ever since about the mid 90s.

buickanddeere · Jul 19, 2014

(quoted from post at 10:46:55 07/19/14) I don't get your remark B&D,you only need 2 plus ground for 240 only.But if someone goes(asks) to buy wire for a 240 job(need),99% chance they will be given a 4 conductor wire(which is what I said).

Ok, i had wondered what you ment.

M-MAN · Jul 19, 2014

John T;
If persistence is a virtue your bucket ran over long ago.LOL Keep on trying though cause it may just work once in a while.

Personally I tend to go overboard. I don't use 14g on anything over 12 volts. For sure you can and it will be safe I just don't like it so I don't use it. Always take the amps I need to get the wire size and then go one size bigger. Doesn't work any better but I sleep better that way.lol

BTW - I've seen more jackleg wiring that scared me done by qualified licensed electricians than by Billy Bobs so you might want to add { That do things correctly! } Even had an electrician / lineman from the local power company tell me one time it's ok to backfeed a genny through a welder plug when the power is out. The odds of finding a good electrician (qualified or not) are the same as a plumber, mechanic, or sweeper. JMO

John T · Jul 19, 2014

I have no problem going a bit overboard, Im wired the same way so long as "reasonable" Yeah maybe I should add a "competent qualified experienced professional" in my recommendations??

I have been told before I'm persistent but that just has to do with my personality type and maybe a tad of OCD here n there lol Silly Me I indeed keep trying fer sure

John T

dr sportster · Jul 19, 2014

You are a very patient instructor. You really care. Trouble is your trying to teach a class full of wise guys.

dr sportster · Jul 19, 2014

" they didn't say that I just added it" Now that is hilarious.

John B. · Jul 19, 2014

I'm glad you took the time to post this John T. I enjoy reading your information all the time. Keep up the good work. Our son is going into Electrical Field. He starts his 2nd year at Ranken Technical College next month. He's going an extra 6 months to get in to Control System Technology.

60 acre hillside · Jul 19, 2014

John T, Technology ?s Is flux a result of induction? Is an eddy current a flux?

John T · Jul 19, 2014

I think in todays world HE MADE AN EXCELLENT CHOICE and will likely even enjoy his job. I"m glad way back when I was a pimpled pre teen I took an interest in electricity, it served me well. Thanks for the kind words.

John T

John T · Jul 19, 2014

Told ya that word made me nervous lol this is NOT my best area....A magnetic field flux results from current flow in a wire but I don't view that as induction. However if the field collapses then voltage can be induced into a wire or coil near by, I call that induction????? I think eddy current is a result of differing flux strength resulting in a potential voltage difference therefore current flow???????????

HEY IM OUT TO LUNCH HERE DONT PLACE TOO MUCH ON THE ABOVE

ABSOLUTELY NOOOOOOOOO WARRANTY ON THIS its been too darn long

John T

massey 333 · Jul 19, 2014

John,the reason I even answered Gregs remark was the average non electric person will look-think when they look-see a 4 conductor wire,they will think or assume it is a 220-240 electric wire,which is good on everybody part.Seller and user,you know LAWYERS. I was taught-schooled many yrs.ago on electric wiring,but never used it for $$$$ gain much.Plus I will help someone,BUT NEVER GIVE ADVICE,here or real life on anything unless noway they can get hurt-killed.

Geo-TH,In · Jul 19, 2014

JohnT,
Is the law firm the one for structured settlement, "IT'S MY MONEY AND I WANT IT NOW?"

I've worked with electricity for about 50 years. Got nailed a few times. Each time it was my fault, stupid mistake for trusting meters. One time my tester lied to me while I was standing on a rubber roof. Grabbed a hold of 440v. That will make you buzz all night. Made me never trust meters. I check with a meter, then make a short to ground using two screwdrivers before I touch anything. Had the tips of screwdrivers damaged, but I'm still alive.

I know of at least 6 people who died, electrocuted, each was a stupid mistake. None of the deaths that you could blame Bubba or Billy Bob for.

One was a farmer working on an irrigation pump. Mistake, he didn't know what he was doing.

Another was a young man who thought he was a service tech working on a centeral AC.

A barefoot man trimming a tree. Tree got in to the power lines.

Lightning got a three phase roof top AC. Tech pulled disconnect and thought the power was off. Lightning welded the disconnect together.

A tech had the service pannel open on a 13,400v. He pointed to the problem. Electricity jumped to his finger and came out his elbow.

A kid touched an outside faucet to get a drink. Something made the faucet hot. Don't know the details, but no one was arrested. Kid was killed. Hard to say what happened. It was an old house.

5 of the 6 deaths I know of the wiring was to code. The Kid's death is the only one I have limited knowledge of the details.

I know there always seems to be a rash of house fires around Christmas. They always say it was an electrical fire in attic. Something related to over loaded circuits, space heaters.

So, Do you have any stats on how many people die because of BUBBA and Billy Bob's stupidity?
George

Greg K · Jul 19, 2014

9 times out of ten it means it has a black outer covering like #8 or larger Romex or the older Romex from the 70's.

David G · Jul 19, 2014

I do control systems for a living, always interesting.

Anonymous-0 · Jul 19, 2014

Eddy currents are caused by magnetic flux. Eddy currents are part of what causes a transformer to be warm when not loaded.

240 VAC Wiring

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Well-known Member

Well-known Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Similar threads