None that I’m familiar with require a neutral. But if you install a 14-50, it could get used for something other than an EVSE.
Pre Wire For Future Car Chargers
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None that I’m familiar with require a neutral. But if you install a 14-50, it could get used for something other than an EVSE.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
If 210.19(A)(1)(a) gets deleted, then 210.20 will still require a 60A breaker, but 240.4(B) would allow a 55A ampacity conductor to be protected at 60A, so that's fine. Ampacity is a continuous rating per the definition, so the load only needs a 48A ampacity conductor. The breaker is the weak link.
I'm not aware of any other language would still require a 60A ampacity for the branch circuit. The corresponding change would need to be made in Article 215 also.
Cheers, Wayne
For a 48A charger there must be 60A circuit. The 60A circuit must be #4 AWG with minimum #8AWG ground. There is nothing in the code to stop anyone from using larger wires. But using #6 AWG is not legal despite convoluted reasoning of some who make such claims. The #6 Romex allows 55A, but the code requires 125%x48A=60A. My advise is to get #3 (L1,L2, N) and #6 ground in a 1.25 thin conduit. When time comes for a bi-directional 80A using #2 AWG and 100A breaker - you'll just change wires & the breaker. Or else do #2 now.
Just remember the code is minimum safety standard...you can always do better than code.
Just remember the code is minimum safety standard...you can always do better than code.
Just because the chargers do not use N today - it does not mean it will not change tomorrow. Circuits usually stay for 30 or more years.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
All these posts saying 6/3 NM "maxes at 55 amps" and "only allows 55 amps"
Look at your ambient temperature correction factor table.
That's 55 amps is if your room temperature is 26 to 30 Celsius, which is 78.8 to 86 degrees Fahrenheit. Who the heck keeps their house at 79 degrees? I don't know of anyone.
If that house is between 69 and 78 degrees Fahrenheit, you have a correction factor of +8%
That means a 6/3 NM has a ampacity of 59.4 amps.
(55 X 1.08 = 59.4)
And 6/10ths of an amp doesn't amount to a hill of beans
Look at your ambient temperature correction factor table.
That's 55 amps is if your room temperature is 26 to 30 Celsius, which is 78.8 to 86 degrees Fahrenheit. Who the heck keeps their house at 79 degrees? I don't know of anyone.
If that house is between 69 and 78 degrees Fahrenheit, you have a correction factor of +8%
That means a 6/3 NM has a ampacity of 59.4 amps.
(55 X 1.08 = 59.4)
And 6/10ths of an amp doesn't amount to a hill of beans
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
With all the variations regarding EV charging and differences between MFG the only Pre-installation I see as practical is as already suggested is to have it piped to the practical charging point, but not wired. The only other consideration I can think of is planning for that load at the highest potential "today" in sizing the service prior to installation. You really don't want to have to change out service to allow for the added loads in a year or two after the original installation was done. Most time oversizing system that small amount would be way less costly than having to change later. Of course this field is changing faster than even code can keep up with, and even what was the largest available a year ago is being eclipsed today by the Ford "Lightning" at 80A.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
When I once wired a basement, I added a 100 amp 12 space subpanel on the back wall of their 2-car garge for future. There wouldn't be any more access once drywall was installed.
That gave him plenty of capacity to do whatever later
Knowing how an EVSE (it’s not a “Charger”) functions, there is no technical reason or advantage to use a neutral.
It’s much more likely that a circuit installed today for an EVSE will be obsolete in the future because it’s too small, not because it needs a neutral.
xformer
Senior Member
- Location
- Dallas, Tx
- Occupation
- Master Electrician
Would this comply with 240.4 (B) (1) ?
"Ambient"- here it does not mean "room" nor in your house. Ambient means "surrounding". I KansasCity ambient temperature reached 100F in July 2021. On the sunny side the wires were most likely exposed to higher temp. than that.All these posts saying 6/3 NM "maxes at 55 amps" and "only allows 55 amps"
Look at your ambient temperature correction factor table.
That's 55 amps is if your room temperature is 26 to 30 Celsius, which is 78.8 to 86 degrees Fahrenheit. Who the heck keeps their house at 79 degrees? I don't know of anyone.
If that house is between 69 and 78 degrees Fahrenheit, you have a correction factor of +8%
That means a 6/3 NM has a ampacity of 59.4 amps.
(55 X 1.08 = 59.4)
And 6/10ths of an amp doesn't amount to a hill of beans View attachment 2559800
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
How far away from the wire/cable does "surrounding" apply?
If it's outdoors then by all means it's probably 50 miles. But if there's conditioned space surrounding your cable, and an insulation barrier between that conditioned space and the outdoors, then inside has to be ambient.
Some spaces (like server rooms) have an ambient temperature much higher than what's outside
rjniles
Member
- Location
- Coastal South Carolina
I would run 2-2-2-4 AL SER. Gives you lots of options and about $2.25 a foot is considerably cheaper than 6-3 NM.
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Do you suggest that your wires carry electricity only if the AC works? I would calculate for worse case - not for best case. Anyway - your own calc shows 59.4 A, this is not 60A - in case you did not notice. It anything happened - the insurance company would deny the claim based on 59.4A
I do not suggest you should use the neutral if your device has no neutral nor the functional or safety need for it.
I am suggesting that the circuit should be complete and include L1, L2, N, and Ground.
FYI:need to distinguish between a circuit, i.e. the wires out of the load center, and the device design. The device may not require aall the wires from the circuit. As you know many today's 240V EV "charging devices do not have neutral. This is because they do not use 120V. Today they do not use both240V and 120V. But some of them may becomesmarter yet in the near future andmay need the 120V.
How many residential circuits installed years ago cannot be used with smart automation today just because they do not have neither neutral nor ground. Anyway it would be unsafe to feed the return current to ground wire.
- not on your fat finger argument.
The code is a minimum standard nothing prevents anybody from doing a safer or better.
Code often wants you to use manufacturer's instructions. The 48A EV charging appliance instruction (JuiceBox48, Tesla) recommends #4awg wires. I am sure they would not object to #6 but not if their liability is involved.
The main, if not only, purpose of the code is safety - why looking for loopholes. I do know that in that application #4 is safe under nearly all conditions, and #6 becomes iffy with temperature variations, number of wires in a tray, specific wire type, and the user dialing in higher charging amps. Electricians are supposed to know related physics too. It is not just paragraphs written to make your life difficult just for a heck of it.
Barbqranch
Senior Member
- Location
- Arcata, CA
- Occupation
- Plant maintenance electrician Semi-retired
Seems like it some times. Especially when it tries to become a design manual.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Absolutely. Aluminum SER is my first choice for feeders, chargers, hot tubs, generators, etc.
The only reason for the code becoming a design manual is that all too many licensed pros do not know physics, try to cut corners, actively look for loop-holes to cut costs, and fail to understand the basics of safety and liability.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I do not have a big issue with the code coming up with some rules that can be applied without requiring much thought. That just simplifies things for everyone.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
The physics says that #6 copper wire in an ambient temperature of 30C, with not more than 2 other current carrying wires in proximity, will carry 48A continuously without exceeding a 60C wire temperature. At least that is what Table 310.15(B) tells us.
However, due to the limitations of other equipment (breakers), and due to an apparent goal of being simple and prescriptive, the NEC does not allow that for #6 copper wire with 60C insulation. I think this is an example of the NEC going too far in being prescriptive.
Cheers, Wayne
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