40 amp charging on 8 awg copper.

[Rtashiro]

Hi,

was hoping to get some advice from some experts.
When I got my first Ev (mustang mach e) I hired an electrician to install a NEMA 1450 in my garage. At the time I was using the 30 amp mobile charger but I specifically requested him to install the plug so I could go up to a 40 amp charger in the future. It has worked fine. I eventually got a 40 amp charger which I have used for about a year now and never threw a breaker or anything. From watching YouTube videos I have seen that the cheap 1450 stove plugs are a no no. Sure enough I checked the plug and it was starting to show signs of melting and when it has been charging a while the plug was quite hot. I decided to change the plug out with an Ev rated one. In doing this I see that the wire is 8awg copper which the internet tells me is good for 40 amps continuous which is good. My issue is that he installed a 40 amp breaker. My understanding is that you shouldn’t run the full capacity of your breaker. Then when I looked at upgrading the breaker it said that a 50 amp breaker requires 6awg wire. Is it fine to run the 40 amps as long as it isn’t tripping the breaker? Or am I stuck degrading down to 32 amps? The text cable is mostly running outside. It goes from the panel, straight outside then under a deck to the garage then into the garage. Just want everything to be safe. The wire itself never seemed to be getting any warmer than the charger cord itself.

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[Heliian]

As long as the components of the circuit are rated for 75degC or higher then you're fine installing a 50a breaker.

Ev rated

It's a marketing scam, they rebadge their hd receptacles and charge another $10.

 

[Yellow Buddy]

Hi,

was hoping to get some advice from some experts.
When I got my first Ev (mustang mach e) I hired an electrician to install a NEMA 1450 in my garage. At the time I was using the 30 amp mobile charger but I specifically requested him to install the plug so I could go up to a 40 amp charger in the future. It has worked fine. I eventually got a 40 amp charger which I have used for about a year now and never threw a breaker or anything. From watching YouTube videos I have seen that the cheap 1450 stove plugs are a no no. Sure enough I checked the plug and it was starting to show signs of melting and when it has been charging a while the plug was quite hot. I decided to change the plug out with an Ev rated one. In doing this I see that the wire is 8awg copper which the internet tells me is good for 40 amps continuous which is good. My issue is that he installed a 40 amp breaker. My understanding is that you shouldn’t run the full capacity of your breaker. Then when I looked at upgrading the breaker it said that a 50 amp breaker requires 6awg wire. Is it fine to run the 40 amps as long as it isn’t tripping the breaker? Or am I stuck degrading down to 32 amps? The text cable is mostly running outside. It goes from the panel, straight outside then under a deck to the garage then into the garage. Just want everything to be safe. The wire itself never seemed to be getting any warmer than the charger cord itself.

The breaker needs to be sized to the circuit. You could theoretically have upsized wiring and a lower breaker as the breaker is sized to protect the wire.

I’m including an ampacity chart for you: https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/

Additional calculations may be needed depending on the type of install, distance, material (aluminum? Copper?) etc.

 

[Robob]

If it was me, I would keep it as is with the 40a breaker. Just de-rate the charger to 38 or 36a for peace of mind. You could also set the charger for 80% of max capacity if really worried for more of a safety cushion.
As long as it’s copper not aluminum wire it should be ok, as always if not wanting to trust random people on the internet have a sparky come look at it, most reputable electrician‘s will come do an on site safety inspection for 100 or less, sometimes free if you offer food/beer.

Also I noticed it says Winnipeg for your location, google says it’s avg max temp is 80f/27c in hottest months so at 38/36a I would say your fine, once it’s cold out jump back up to 40a

 

[Rtashiro]

As long as the components of the circuit are rated for 75degC or higher then you're fine installing a 50a breaker.





It's a marketing scam, they rebadge their hd receptacles and charge another $10.

there was a noticeable quality difference between the $5 stove plugs that was in there originally and the Leviton heavy duty one ($60) that was Ev rated. The terminals were heavy duty copper and tightened to 75 inch lbs. it seems well rated. Could not justify the $200 plus for the Hubble that appears to be very similar.

 

[flyct]

there was a noticeable quality difference between the $5 stove plugs that was in there originally and the Leviton heavy duty one ($60) that was Ev rated. The terminals were heavy duty copper and tightened to 75 inch lbs. it seems well rated. Could not justify the $200 plus for the Hubble that appears to be very similar.

An Industrial Hubble 9450A is only $57 now
https://www.amazon.com/Hubbell-HBL9450A-Wiring-Grounding-Receptacle/dp/B0137HMGGS/

I installed a Bryan 9450FR for $60 is equivalent to the Hubbell and made by Hubbell.
https://www.amazon.com/dp/B003A2R9RM

Both require a different wall plate due to them being bigger and more robust.

 

[Rtashiro]

An Industrial Hubble 9450A is only $57 now
https://www.amazon.com/Hubbell-HBL9450A-Wiring-Grounding-Receptacle/dp/B0137HMGGS/

I installed a Bryan 9450FR for $60 is equivalent to the Hubbell and made by Hubbell.
https://www.amazon.com/dp/B003A2R9RM

Both require a different wall plate due to them being bigger and more robust.

You are right it has come down in price. I’m in Canada paying Canadian pesos unfortunately. Up here it’s 108. I paid half that for the one I got and it seems solid. If it doesn’t work out I may switch to the Hubble or bryant (Bryant here is even more than the Hubble right now on Amazon. I paid 60 Canadian for the Leviton. ($45 usd)

 

[Heliian]

there was a noticeable quality difference between the $5 stove plugs that was in there originally and the Leviton heavy duty one ($60)

Yes, don't buy the cheapies.

 

[Red_Flash]

Yes, don't buy the cheapies.

For a 40 amp circuit with a continuous load the load should not be more than 80% of the circuit rating (32amps).

 

[hturnerfamily]

"...I see that the wire is 8awg copper which the internet tells me is good for 40 amps continuous which is good. My issue is that he installed a 40 amp breaker..."

'he' is correct

- the Breaker is your MAIN line of defense: Safety of the wire from overheating.
This 40 amp installed breaker is Exactly the correct size for 8 awg wiring...

- the WIRE size, 8 awg, is for up to 40 amps...

Should you use a '40 amp' EVSE with 8 awg wiring on a 40 amp 240v breaker?
Sure. It's designed for that.
Some, though, will say that you should not use up to the maximum rating of wiring, or up to the size of the breaker, when using continuous AMPERAGE, for hours and hours, such as an EVSE does. The '80%' rule, of sorts, is talking about keeping an amount of 'room' within the breaker's maximum rating, in order to prevent nuisance tripping, and/or overheating of the breaker. But, that's exactly what a breaker is for - the trip when too much HEAT is at a Constant rate - to protect the underlying 8 awg WIRING from overheating.

An 8 awg wire, though, is not rated for 'exactly' 40 amps, as though at that Amperage it will suddenly overheat, arc, and start a potential fire, but that it's SHEATHING/Coating is designed to protect everything around it from that amount of heat, potentially also burning thru the coating, itself. It's not an 'exact' measure, though.

"8 AWG (American Wire Gauge) copper wire ampacity depends on its insulation's temperature rating:

• 60°C (140°F): common building wires like TW/UF cables, rated for 40 amps.
  
  
• 75°C (167°F): Higher capacity wires like THW, RHW, and THHN, allowing for 50 amps.
  
  
• 90°C (194°F): Highest capacity wires with higher temperature ratings, such as THHN/THWN-2, rated for 55 amps. "

Check your type of wiring.

 

[Red_Flash]

"...I see that the wire is 8awg copper which the internet tells me is good for 40 amps continuous which is good. My issue is that he installed a 40 amp breaker..."

'he' is correct

- the Breaker is your MAIN line of defense: Safety of the wire from overheating.
This 40 amp installed breaker is Exactly the correct size for 8 awg wiring...

- the WIRE size, 8 awg, is for up to 40 amps...

Should you use a '40 amp' EVSE with 8 awg wiring on a 40 amp 240v breaker?
Sure. It's designed for that.
Some, though, will say that you should not use up to the maximum rating of wiring, or up to the size of the breaker, when using continuous AMPERAGE, for hours and hours, such as an EVSE does. The '80%' rule, of sorts, is talking about keeping an amount of 'room' within the breaker's maximum rating, in order to prevent nuisance tripping, and/or overheating of the breaker. But, that's exactly what a breaker is for - the trip when too much HEAT is at a Constant rate - to protect the underlying 8 awg WIRING from overheating.

An 8 awg wire, though, is not rated for 'exactly' 40 amps, as though at that Amperage it will suddenly overheat, arc, and start a potential fire, but that it's SHEATHING/Coating is designed to protect everything around it from that amount of heat, potentially also burning thru the coating, itself. It's not an 'exact' measure, though.

"8 AWG (American Wire Gauge) copper wire ampacity depends on its insulation's temperature rating:

• 60°C (140°F): common building wires like TW/UF cables, rated for 40 amps.
  
  
• 75°C (167°F): Higher capacity wires like THW, RHW, and THHN, allowing for 50 amps.
  
  
• 90°C (194°F): Highest capacity wires with higher temperature ratings, such as THHN/THWN-2, rated for 55 amps. "

Check your type of wiring.

According to the national electric code a continuous load (>3hrs) cannot exceed 80% oh the circuit rating.

 

[RLXXI]

I had my electrician use 4 awg for my run of about 35' using a 60a breaker and charging max of 48a. I know it's overkill but I'd rather have a little buffer as it gets hot as hell down here.

 

[Jseis]

I run our CP Flex at 32 amps on 8 AWG copper. and a 40 amp breaker. Someday upgrade to charge at capacity but I still can put on 100 miles in ~5 hours so no biggie right now. I’m saving so much on fuel ($4.50 a gallon v. $.064 per kW) that savings on commuting is $$ in the bank. However the deductible cost per mile to operate a car is up $.72 per mile so… no such thing as a free lunch.

 

[ccough]

Installed an Emporia EVSE unit almost 2 years ago. Length of run can be a consideration, but 6 AWG was what came out of information from NEC. When the Emporia arrived, it also stated that 6 AWG should be installed (implied even for shorter runs). This was for 40 amp charging on a 50 amp circuit breaker. 8 AWG copper should be run on no more than 40 amp breakers, and continuous loads like charging should be set to 80% of that (32 amps), at most. This is what electrical code calls for.

Regarding the plug, after researching those it seems that there are some good options out there (Hubbell) but I decided to hardwire the EVSE to avoid plug issues.

 

[RickKeen]

If you really want 40 amp EV charging, you need 6AWG with a 50 amp breaker.
I would skip the plug - hardwire the charger connection. Less connections to fail and get hot and catch on fire. Also its cheaper anyways. (no box, and no $57 plug).

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