Is This Sufficient?

[Fatawan]

When I had our house built, the electrician wired the garage for what he said was a "standard 50A charger." I have attached a pic of what is behind the cover plate. The breaker in the panel is a 40A breaker. Is this wire sufficient for a 50A circuit if I changed the breaker in the panel? Do you see any reason he would have put just a 40A breaker in the box?

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[Clydesdale]

When I had our house built, the electrician wired the garage for what he said was a "standard 50A charger." I have attached a pic of what is behind the cover plate. The breaker in the panel is a 40A breaker. Is this wire sufficient for a 50A circuit if I changed the breaker in the panel? Do you see any reason he would have put just a 40A breaker in the box?

What gauge wire is it? Are there any marking on the sheathing? Also how far from the breaker is the outlet?

 

[Jimrpa]

40A breaker will only support a maximum 32A load, per standard practice and most codes. Invite him back for a redo. While you’re at it, ask him where he gets his 62.5A breakers ?

 

[goldriver]

Can you see any mention on the wire lie 3/10 or 3/8 ? it would be written on the outside skin of the wire (if you have an acces at electrical panel side you'll probably have a better view of the outside wire skin)

with the attached picture it is hard to know the size of the wire (it could be a 10, 8 or ???)

 

[ocdxfv]

Can you see any mention on the wire lie 3/10 or 3/8 ? it would be written on the outside skin of the wire (if you have an acces at electrical panel side you'll probably have a better view of the outside wire skin)

with the attached picture it is hard to know the size of the wire (it could be a 10, 8 or ???)

The wire should have some markings on it. Take a photo of the wire markings and post it. My guess is that you have #8 wire (with a 40a breaker) and the wires probably say "THHN or THWN-2" or something similar.

 

[Fatawan]

No markings on the wire in the outlet--I will open up the panel and check

 

[ocdxfv]

No markings on the wire in the outlet--I will open up the panel and check

When you open the panel, locate any other 240 volt breakers (dryer, oven, A/C, pool, etc) and visually compare the size of the wires. The 240v breakers should have bigger wire than the 120v breakers, and your 40a charger circuit should have bigger wires than the 30a and the same as any other 40a breakers.

 

[Fatawan]

This is a subpanel on one end of the basement(long skinny house). The breaker in the main panel for this sub panel is 70A. The subpanel is within 20-25' of the outlet in the garage. The wires have no markings of any sort on them. It wasn't individual wires, but sheathed. The two breakers in the upper right are 30A and those wires are considerably smaller. The car charger breaker is lower left(sorry about the rotation!). If there is anything else I can get that might help, let me know. Thank you all.

 

[CHeil402]

This is a subpanel on one end of the basement(long skinny house). The breaker in the main panel for this sub panel is 70A. The subpanel is within 20-25' of the outlet in the garage. The wires have no markings of any sort on them. It wasn't individual wires, but sheathed. The two breakers in the upper right are 30A and those wires are considerably smaller. The car charger breaker is lower left(sorry about the rotation!). If there is anything else I can get that might help, let me know. Thank you all.

Without knowing the gauge / makeup of the wire it's impossible to tell if the wire is properly sized for a 50 A breaker. Check out the table here which can answer your question if you can find the right row and column... https://www.wireandcabletips.com/what-is-ampacity/

Also, based on your description having that much downstream in the sub-panel from a 70 A breaker doesn't sound like a good idea (not unsafe, just prone to nuisance tripping of the 70 A upstream breaker). Ignoring all of the other 120 V circuits, I see a dryer and oven in there. If you ran the EVSE at the same time as the oven and/or dryer, that upstream 70 A breaker is likely to trip... that may be a reason your electrician installed only a 40 A breaker. Even if the wire is sized properly, you MAY run into issues pulling that much current from that one load in that sub-panel if you're running a bunch of other stuff at the same time.

 

[Fatawan]

Sounds like I should just install a 14-50 plug and use the charging cable that comes with the car, or something like a Grizzle-E set to 32A. No reason to push the limits here. Thanks again.

 

[CHeil402]

Sounds like I should just install a 14-50 plug and use the charging cable that comes with the car, or something like a Grizzle-E set to 32A. No reason to push the limits here. Thanks again.

You might also want to put a label on the outlet that it's rated for 40 A and not 50 A since a NEMA 14-50 plug is supposed to be 50 A per code. Otherwise you (or someone in the future) might put something that draws the maximum from a NEMA 14-50 of 40 A which would result in annoying nuisance trips at best... or if the cable is actually only rated for 40 A and the CB tolerance is a little high an unsafe condition at worst.

Also... if you're having any nuisance trips, you can set the Grizzl-E to a lower current level so long as it meets your recharge rate needs. Most people don't actually need the full capabilities.

 

[JCHLi]

It's difficult the gauge the gauge of wire used. Do you have a set of dial calipers or inside micrometer?

 

[ocdxfv]

It's difficult the gauge the gauge of wire used. Do you have a set of dial calipers or inside micrometer?

Those look like #8 wires which are correct for the 40a breaker. I would NOT change the breaker to 50a. I would follow the previous suggestion of using the charger that came with the car AND labeling the outlet as "40 amp MAX, 32 amp continuous". Charging at 32 amps will serve you well.

 

[JCHLi]

Those look like #8 wires which are correct for the 40a breaker. I would NOT change the breaker to 50a. I would follow the previous suggestion of using the charger that came with the car AND labeling the outlet as "40 amp MAX, 32 amp continuous". Charging at 32 amps will serve you well.

You're eyes must be better calibrated then mine.

 

[Fatawan]

Probably not exactly what you were after, but best I got!

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