40 amp charging on 8 awg copper.

[Rtashiro]

This is the image of the plug I took off that was getting hot. Plug didn’t melt but was getting very hot. Just at the plug. The wire showed no sign of heat on the insulation and this was after 3 years running at 40 amps. There was some damage to the conductor where the original electrician nicked the conductor when he stripped it. I cut off the ends, re stripped it, and fully torqued the lugs on heavy duty plug to 75 inch pounds. Tugged the wires around then re tourqued. No heat whatsoever at 40 amps after several hrs. Of 40 amp draw. No heat on the plug or the conductors.

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[K6CCC]

Bad job on wiring the plug. Way too much exposed wire on those terminals. And perfectly legal and commonly done, but personal preference is to NEVER use bare wire for ground in a box with exposed terminals.

 

[Rtashiro]

Bad job on wiring the plug. Way too much exposed wire on those terminals. And perfectly legal and commonly done, but personal preference is to NEVER use bare wire for ground in a box with exposed terminals.

yeah I thought the same but the Teck cable has a bare ground. Also I thought the same about too much stripped but when I re stripped I used the strip length gauge on the outlet and it left some exposed copper. I didn’t take a photo of the new plug to compare. The old cheap plug also had pathetic terminals compared to the heavy duty one. If I put 75 inch pounds in the old one I believe it would have broke into a million pieces.

 

[Evans]

This should not be that confusing. A 50 A circuit using a 50 A breaker with a NEMA 14-50 receptacle (industrial grade) is required to use 6 AWG wire per the NEC code. All components need to be rated for 50A. A continuous load such as an EV must be derated to 80% per NEC. An EVSE on such a circuit can supply 40 A continuously. Since you have 8 AWG already installed the wire rating drops the circuit rating to 40 A and a corresponding 40 A breaker is needed since the 80% derating still applies for continuous loads. The EVSE can only be set to a maximum of 32 A. The wire size for the circuit in this case dictates the current rating of all the components. So yes 8 AWG wire can be used in a 40 A circuit as long as the continuous current draw is limited to 32 A.
Disclaimer:
Nothing written above should be considered professional advice and I'm not responsible for anything, either explicit or implied.

 

[P-38]

No.
The ampacity of 8 AWG depends on the insulation type. If you use an insulation type from column 2 or 3 you are good to go at 50 amp, assuming conduit fill and voltage drop are not a problem.

 

[Evans]

Good catch on the higher temp wire.

 

[Rtashiro]

No.
The ampacity of 8 AWG depends on the insulation type. If you use an insulation type from column 2 or 3 you are good to go at 50 amp, assuming conduit fill and voltage drop are not a problem.

The specific cable I have is rated to 55 amp and 90 degrees c

 

[Rtashiro]

Any Canadians electricians here? What I’m seeing online is Canadian code says 8awg is good for 50 amps as long as it is rated 75 degrees or higher. Still doesn’t help me having 40 amp breaker but raising the breaker to 50 amp from 40 seems less safe rather than more safe.? Taking away from the safety net by changing breaker. It’s hasn’t tripped yet. Link to stats on the cable I have installed

 

[P-38]

The specific cable I have is rated to 55 amp and 90 degrees c

Right. Using NEC rules the wire would be ok to 55amps but the outlet and breaker would only be rated for 75 degrees C, which would mean one would need to use the 75 C column as the breaker or outlet are only rated to allow the copper to get to 75C.

I don't know enough about Canadian rules to say that you could put a 60 amp breaker on the wire (60 being the next standard size above 55).

In my experience sending equipment to Canada and Europe 50 amp breaker on 90C rated wire would be ok as long as I use a breaker and outlet that are at least 75C rated.
But this is where you could ask a Canadian electrician.
It could be that your 40 amp breaker on a 40 amp load is 100% right per Canadian rules. It's not per NEC which is generally what the code is in the US.

For continuous loads we in the US have to upsize to 125% of the load, so a 40 amp continuous load requires a 50 amp circuit. Often this requirement is expressed as the load can be 80% of the circuit, but on the design side you start with load and make your circuit capable of suppling 125% of the load.

 

[P-38]

Any Canadians electricians here? What I’m seeing online is Canadian code says 8awg is good for 50 amps as long as it is rated 75 degrees or higher. Still doesn’t help me having 40 amp breaker but raising the breaker to 50 amp from 40 seems less safe rather than more safe.? Taking away from the safety net by changing breaker. It’s hasn’t tripped yet. Link to stats on the cable I have installed

Yeah if it's not tripping leave it as is since the wire and outlet are good to 50. If you get nuisance tripping then ask a Canadian electrician about up sizing or local inspector if you have one like US permits require

 

[Rtashiro]

Right. Using NEC rules the wire would be ok to 55amps but the outlet and breaker would only be rated for 75 degrees C, which would mean one would need to use the 75 C column as the breaker or outlet are only rated to allow the copper to get to 75C.

I don't know enough about Canadian rules to say that you could put a 60 amp breaker on the wire (60 being the next standard size above 55).

In my experience sending equipment to Canada and Europe 50 amp breaker on 90C rated wire would be ok as long as I use a breaker and outlet that are at least 75C rated.
But this is where you could ask a Canadian electrician.
It could be that your 40 amp breaker on a 40 amp load is 100% right per Canadian rules. It's not per NEC which is generally what the code is in the US.

For continuous loads we in the US have to upsize to 125% of the load, so a 40 amp continuous load requires a 50 amp circuit. Often this requirement is expressed as the load can be 80% of the circuit, but on the design side you start with load and make your circuit capable of suppling 125% of the load.

im thinking now my wire and plug is rated for 50 amp breaker I just don’t have the breaker.

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