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Wall Charger Amp Setting

nwdiver

Well-Known Member
Feb 17, 2013
8,589
11,977
United States
I had an electrician install the wall connector and he put in a 50-amp breaker but set the charger to charge at 60A. Is that a hazard? Can I buy a 60A breaker and swap it out? Or is there more to it?

I'm absolutely amazed at how often this happens. In my experience it's almost ~50% of installs....
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
1,903
2,111
Massachusetts
It should not be your job to fix his install. If the wire is rated for 60 amps, he should come out and replace the breaker free. If it is NOT rated for 60 amps(48 continuous), you should recommission the HPWC to correspond to a 50 amp breaker(40 amps continuous)

A 60 amp breaker would be okay for 4AWG in NM-B(sheathed) wire, or 6AWG in individual wires in conduit(these are for copper conductors).

I'm not sure I'd trust the electrician any more. I certainly wouldn't be requesting his services on another job.
 

mjbigelow

Member
Jul 21, 2021
29
91
WA
It should not be your job to fix his install. If the wire is rated for 60 amps, he should come out and replace the breaker free. If it is NOT rated for 60 amps(48 continuous), you should recommission the HPWC to correspond to a 50 amp breaker(40 amps continuous)

A 60 amp breaker would be okay for 4AWG in NM-B(sheathed) wire, or 6AWG in individual wires in conduit(these are for copper conductors).

I'm not sure I'd trust the electrician any more. I certainly wouldn't be requesting his services on another job.
Really? This is that big of a deal?
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
1,903
2,111
Massachusetts
Is this a big deal? I have no knowledge of electrical matters.
Will it burn your house down... no . The breaker might trip due to overheating, especially if there are other nearby breakers moving lots of current or the ambient temperature gets high.

I am actually running an HPWC in my garage(set to 48 amps) on a 50 amp breaker. There's a TON of safety built into the NEC rules. In my case, my 6-2 NM-B(except for a foot or so) is running through my basement(62-65f all year round) and to my basement electrical panel. After hours of 48 amp charging, the wire gets to like 88f of its max rating(140f).

I totally don't need to charge at 48 amps either, so I might just turn it back down to 40.
 

nwdiver

Well-Known Member
Feb 17, 2013
8,589
11,977
United States
Is this a big deal? I have no knowledge of electrical matters.

I don't know how big of a deal it is since there's so much margin built into wire ratings. When they installed the chargers where I worked they put 40A chargers on a 40A circuit instead of a 50A circuit so the breaker kept tripping. And these were electricians working at a nuclear facility. Supposedly the best of the best. Just amazing how often this happens. How hard is it to divide a number by 0.8 to determine the required circuit rating?
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
1,903
2,111
Massachusetts
Really? This is that big of a deal?
So this time you got lucky.. the breaker he installed may be appropriate for the wire he installed. What happens the next time when you aren't lucky, and he puts a 50 amp breaker on #10 because that's what he had on the truck. For that matter, we actually don't know what he installed for your HPWC. If its less than #6, your house is definitely in danger. (Less than means #8 or #10, in this case.)
 

mjbigelow

Member
Jul 21, 2021
29
91
WA
I don't know how big of a deal it is since there's so much margin built into wire ratings. When they installed the chargers where I worked they put 40A chargers on a 40A circuit instead of a 50A circuit so the breaker kept tripping. And these were electricians working at a nuclear facility. Supposedly the best of the best. Just amazing how often this happens. How hard is it to divide a number by 0.8 to determine the required circuit rating?
Holy cow. Also, totally cool that you work at a nuclear facility. I hope we can make a huge switch into nuclear energy soon.
 

mjbigelow

Member
Jul 21, 2021
29
91
WA
So this time you got lucky.. the breaker he installed may be appropriate for the wire he installed. What happens the next time when you aren't lucky, and he puts a 50 amp breaker on #10 because that's what he had on the truck. For that matter, we actually don't know what he installed for your HPWC. If its less than #6, your house is definitely in danger. (Less than means #8 or #10, in this case.)
Very good point. I've got a call in to ask him. Is there a way I can tell by looking?
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
1,903
2,111
Massachusetts
Very good point. I've got a call in to ask him. Is there a way I can tell by looking?

NM-B cable will have it the type stamped on the sheath(probably saying something like AWG6-3 or whatever. If its in conduit, you need to pull the cover off the breaker panel and look at the individual conductors where something similar will be stamped(without the -3, since its not a bundle of wires). Be aware that there's live wiring in that panel. Don't touch anything metal in there unless you know what you are doing, and don't pull up(away from the panel) on any of the wires where they connect to the breakers. These large gauge wires don't bend well, and you can accidentally pull the breaker off its mount, because that's how they usually are installed(pivoting back into the main panel). Its not a real big deal if you pull the breaker, but it can be an unwelcome surprise.
 
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mjbigelow

Member
Jul 21, 2021
29
91
WA
'worked' past tense; Clearly you're not familiar with my nuclear postings :)

Prediction: Coal has fallen. Nuclear is next then Oil.

Great post. I especially like this point: "...if they can compete then they're worth keeping if not then let them die."

I will point out the Ft. Calhoun plant you mention is 55 years old. I worked for a PE fund that backed a company that was creating power from nuclear waste that had a tiny footprint. I think a plant with the latest technology and the ability to upgrade the efficiency by essentially recycling the waste would be a much more stable option that wind and, potentially, solar. What do you think?
 
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jcanoe

Active Member
Oct 2, 2020
4,382
4,565
Maryland
Yes, the wall charger should be 80% of the breaker.
The Tesla Wall Connector should be configured to match the rating of the circuit breaker, never higher than the circuit rating. If the circuit breaker is 50A then you need to set the Wall Connector to 50A. The Wall Connector will limit the maximum charging amperage to 80% of the circuit rating. You don't need to calculate the 80% rule as this is programmed into the Wall Connector.
 

Sandollars

I bleed Cardinal
Feb 19, 2018
364
387
So Cal/So UT
The Tesla Wall Connector should be configured to match the rating of the circuit breaker, never higher than the circuit rating. If the circuit breaker is 50A then you need to set the Wall Connector to 50A. The Wall Connector will limit the maximum charging amperage to 80% of the circuit rating. You don't need to calculate the 80% rule as this is programmed into the Wall Connector.
This ^^^
 

thecavalry

Member
Aug 27, 2021
217
277
Utah
The Tesla Wall Connector should be configured to match the rating of the circuit breaker, never higher than the circuit rating. If the circuit breaker is 50A then you need to set the Wall Connector to 50A. The Wall Connector will limit the maximum charging amperage to 80% of the circuit rating. You don't need to calculate the 80% rule as this is programmed into the Wall Connector.
The electrician likely did not configure the wall charger settings for a 50a breaker. It defaults to 60a when it is first powered up and you must sign in to its broadcasted network to configure it to the correct breaker size. Annoying, but not the end of the world. You do need to reconfigure the connector for the correct size breaker.

No need to call the electrician back, though. It is a simple fix.

Just find the ssid info for the connector in the box, or on the left side of your wall connector unit. Hold the charge handle button for about five seconds to force a reset. Connect to the now visible network and set the breaker to the correct size. Done.
 

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