8 AWG for 50 amps?

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pkulak

Well-known member
Joined
Sep 19, 2013
Messages
758
Location
Portland, OR
This has probably been asked a bunch, but for my short run of about 6 feet, can I use 8 AWG? I'm converting a NEMA 6-50 that was on a 40 amp breaker to a NEMA 14-50. I also went ahead and swapped the breaker up to 50 (because that's what you expect to be able to draw with that plug), when I ran the new neutral line. But, the existing hots are only #8, where I probably would have gone with #6. Can I leave those in there, or do I need to re-run larger wire? Thanks!
 
pkulak said:
This has probably been asked a bunch, but for my short run of about 6 feet, can I use 8 AWG? I'm converting a NEMA 6-50 that was on a 40 amp breaker to a NEMA 14-50. I also went ahead and swapped the breaker up to 50 (because that's what you expect to be able to draw with that plug), when I ran the new neutral line. But, the existing hots are only #8, where I probably would have gone with #6. Can I leave those in there, or do I need to re-run larger wire? Thanks!

I would just run a #8 neutral , replace the 6-50 with a 14-50R and LEAVE THE 40 amp breaker.

The 14/50R is approved on 40 amp circuits. It's done all the time.

As long as the EVSE you plug into it does not exceed 32 amp draw you will be legal and fine. There are no 40 amp 240v specific receptacles.
 
pkulak said:
This has probably been asked a bunch, but for my short run of about 6 feet, can I use 8 AWG? I'm converting a NEMA 6-50 that was on a 40 amp breaker to a NEMA 14-50. I also went ahead and swapped the breaker up to 50 (because that's what you expect to be able to draw with that plug), when I ran the new neutral line. But, the existing hots are only #8, where I probably would have gone with #6. Can I leave those in there, or do I need to re-run larger wire? Thanks!
First. I am not an electrician. There's some good info here: https://teslamotorsclub.com/tmc/threads/faq-home-tesla-charging-infrastructure-q-a.12615/

Based on what I recall, you can use #8 AWG for a 50 Amp circuit if those wires are individual wires in conduit. So, not Romex for example.
 
Thanks! This is exactly what I wanted to know:

For wire-in-conduit, 8 AWG THHN (dry locations) or THWN (wet locations) is sufficient to carry 50 amps, but many electricians will use 6 AWG to ensure that there is enough headroom. The ground conductor must be a minimum size of 10 AWG.

I've got 4 wires in conduit, so I think I'm fine. I would have done 6, but I'm not going to worry about redoing it.
 
I am waiting for our used Leaf to be delivered early this week . Have not purchased a Level 2 EVSE , yet .

2 # 8 hots should be fine but just leave it on a 40 amp 2 pole circuit breaker . I am guessing that is what the EVSE calls for in its labeling and / or documentation .

Pretty certain the EVSE will require 2 hots & an earth ground . Although the Nema14-50 receptacle has a terminal for a neutral , I do not think the 240 VAC EVSE requires a neutral .

God bless
Wyr
 
Considering that both Neutral & Ground land on the same buss, it repetitive!
I used #8 in conduit, 3 ft run! Outlet is next to the panel!
It's all good!
 
KK6PD said:
Considering that both Neutral & Ground land on the same buss, it repetitive!
I used #8 in conduit, 3 ft run! Outlet is next to the panel!
It's all good!
If you used a 14-50r outlet(what this thread is talking about) then what didn't you connect, neutral or ground? I believe the issue with using a outlet that has a neutral and even though your EVSE doesn't use it is if someone else plugs in something requiring a neutral they are going to assume the outlet has a neutral, without one it could cause serious issues. IMO if you were only talking about 3 feet of wire I'd have sprung for the small additional cost to make it not only code compliant but also usable for a device that required the neutral. Now if were talking about a hard wired installation, then no neutral is needed nor required. Lastly if it was just that you didn't have 3 feet of #8 white wire, it's my understanding you can use any color wire you want, your just required to tape the ends of the wire with the correct color(white in the case of a neutral). Thats what I did when I installed a L14-30r outlet on my sub panel, used green wire for the neutral and covered both ends with white electrical tape. Also if your against using a neutral wire then just use the appropriate 240v outlet that doesn't use a neutral(NEMA 6-50 I believe).
True in most panels ground and neutral go to the same buss but I don't believe thats always the case, a sub panel for instance.
 
jjeff said:
KK6PD said:
Considering that both Neutral & Ground land on the same buss, it repetitive!
I used #8 in conduit, 3 ft run! Outlet is next to the panel!
It's all good!
If you used a 14-50r outlet(what this thread is talking about) then what didn't you connect, neutral or ground? I believe the issue with using a outlet that has a neutral and even though your EVSE doesn't use it is if someone else plugs in something requiring a neutral they are going to assume the outlet has a neutral, without one it could cause serious issues. IMO if you were only talking about 3 feet of wire I'd have sprung for the small additional cost to make it not only code compliant but also usable for a device that required the neutral. Now if were talking about a hard wired installation, then no neutral is needed nor required. Lastly if it was just that you didn't have 3 feet of #8 white wire, it's my understanding you can use any color wire you want, your just required to tape the ends of the wire with the correct color(white in the case of a neutral). Thats what I did when I installed a L14-30r outlet on my sub panel, used green wire for the neutral and covered both ends with white electrical tape. Also if your against using a neutral wire then just use the appropriate 240v outlet that doesn't use a neutral(NEMA 6-50 I believe).
True in most panels ground and neutral go to the same buss but I don't believe thats always the case, a sub panel for instance.

You are correct about everything except the code about relabeling. NEC doesn't allow you to relabel a wire which is smaller than #4. Obviously the safety risk of this in your case is so minor that it's not worth fixing IMO but just a heads up. FWIW my electrician friend that helped me replace my panel used black #6 THHN for the GECs and we put green tape over them as that's what he had. The electrical inspector didn't fail us for that even though he should of.
 
QueenBee said:
FWIW my electrician friend that helped me replace my panel used black #6 THHN for the GECs and we put green tape over them as that's what he had. The electrical inspector didn't fail us for that even though he should of.
Actually, GECs, unlike EGCs, aren't required to be green. I'd have to check the NEC to see if they are allowed to be green.

Edit: OK, I checked, GECs can be green. The prohibition on green applies only to circuit conductors.

Cheers, Wayne
 
wwhitney said:
QueenBee said:
FWIW my electrician friend that helped me replace my panel used black #6 THHN for the GECs and we put green tape over them as that's what he had. The electrical inspector didn't fail us for that even though he should of.
Actually, GECs, unlike EGCs, aren't required to be green. I'd have to check the NEC to see if they are allowed to be green.

Edit: OK, I checked, GECs can be green. The prohibition on green applies only to circuit conductors.

Cheers, Wayne

Well no wonder why it passed! Thanks for passing that info along. We are fortunate to have you around!
 
KK6PD said:
Considering that both Neutral & Ground land on the same buss, it repetitive!
...
Madness, simply Madness :!: :shock:

The same stupidity people were using in electric power design Fifty years ago :shock: :eek: :(

Connected to the same point does NOT mean they do the same thing.

They are separate conductors because of SAFETY.

Using a single conductor for both MAY GET SOMEONE DEAD :shock: :eek: :(
 
TimLee said:
Using a single conductor for both MAY GET SOMEONE DEAD :shock: :eek: :(

While not arguing this, the sense of safety that comes from the assumption that neutral can't come loose on the utility supply side is unfortunately false. Grounding rods and bonding to cold water supply pipe can help but no guarantee as well. It took me 3 years to discover than my water main was mostly PVC under ground with galvanized steel segments above the ground, so much for cold water pipe bonding....
 
There's lots of talk on various message boards about 3-wire vs 4-wire connections for dryers (and ranges too, although I think it may be less common for ranges).

I still not sure I really understand it, but it seems a neutral is current carrying, while a ground is not. Also something about "grounding" is actually "bonding", but the effect is that if there is a loose wire, say, inside the dryer, it creates a short rather than just sitting there with a buzz on waiting for someone to touch it and get killed.

On dryers there is a jumper where you connect the pigtail I'm told you are supposed to remove if you are using a 4 wire pigtail but leave in for three wire. So on a three wire connection it seems the shell of the dryer is very much connected to the neutral bus, but the neutral bus is also connected to the ground.

I recall when I was a kid we had a problem where the lights were getting bright in half the house and dim in the other. They said it was a "floating neutral" where the underground cable coming to the house had a nick in the insulation and had corroded. The neutral clearly wasn't at zero volts - apparently the connection to the grounding in the panel was the only thing that kept it from really going to higher potential.

We recently had a new washer/dryer installed at a house for my daughter where the dryer is on a 3 wire connection - and unfortunately the romex is only three conductors. An electrician friend of mine said while they are considered acceptable he really prefers the 4 wire and if it was his house he's change it. My plan is at some point to run a new 10/3+G to the dryer and terminate the old 10/3 w/o G in a junction box for future evse connection. Considering how common 3 wire dryers plugs are it's hard to feel a great sense of urgency, but still it kind of bugs me like it is.

Does anyone know if it's OK to use a white wire for ground if you wrap some green tape on the ends? The old dryer romex has red, black and white.
 
LTLFTcomposite said:
Does anyone know if it's OK to use a white wire for ground if you wrap some green tape on the ends? The old dryer romex has red, black and white.
QueenBee said in a few posts up that you cannot do that on wires smaller than #4 gauge. Doesn't your romex have a bare wire for ground? Personally in your case(unless you had to have it inspected) I'd probably risk it. I mean turning a white wire into green is probably the safest combination, much better than say turning a green wire(which people would assume would be ground) into a hot wire :shock:
 
^ I didn't know what GECs and EGCs were and I was too lazy to google it. Yeah, I was surprised to see romex with no ground wire, didn't know there was such a thing.
 
LTLFTcomposite said:
So on a three wire connection it seems the shell of the dryer is very much connected to the neutral bus, but the neutral bus is also connected to the ground.

The real danger only arises when/if this neutral wire becomes loose or damaged, then you effectively have 120V on the shell of the appliance relative to the ground. With good neutral there is still some voltage on the shell due to the voltage drop on the wiring, but it is too low to be dangerous.
 
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