Circuit breaker popping during 240v charging

[FlasherZ]

Yes it is, however a decent electrician would have put it on from the get go and should not need any more, though, their are many bad electricians who don't use any at all. I hate aluminum wire :-( I always splurge the extra few dollars for copper.

"Few dollars" gets really expensive when you're talking a 100' to 200' of #2, #0, or even 2/0 run from a diesel genset to an indoor location. Just for reference, 2-2-2-4 copper cable runs about $7/ft while 2-2-2-4 AL cable runs about $1.75/ft.

Many people hear horror stories about AL wire, but the context isn't given around it. The AL wire that caused plenty of problems in the 1970's was solid, smaller in-wall wiring similar to the Romex that you use today. The alloy that was used back then was susceptible to tensile strength failures and got brittle after many cycles of expansion and contraction (since copper and aluminum expand and contract at different rates). That wiring (and usually the junctions to other devices) was very problematic.

The AL wiring you get for larger gauge needs today is perfectly safe and acts very similar to copper. In addition, the bonding materials used to connect to AL wire in terminations are much safer than in the 1970's. In fact, while many electricians still insist on using an de-oxidant compound (NOALOX), it is NOT needed in most of today's terminations. UL standards call for testing without a deoxidizer first. Of course, this varies by product and jurisdiction. Some inspectors will require it anyway (although that is rare nowadays), even while most equipment doesn't require it. Adding it doesn't hurt, but you have to follow directions - some DIY'ers just apply the goo to the outside and don't follow the instructions to use a wire brush to work it into the conductor cable and remove oxidation.

For what it's worth, I don't use de-oxidizer on aluminum terminations. The most important element is to properly torque those connections - most people will under-torque the bolts, creating resistance. The proper torque spreads the cable and creates surface contact over a broader area - and you won't get that if you're just screwing it with a "soft hand tight" type approach.

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My understanding is that many breakers trip thermally which is an indicator but an exact measurement of current. So warmer temperatures and lose lugs can exasperate the problem. I was at a KOA and while in theory they had 50 amp breakers but I could not charge above 34 amps without tripping, normally after 20+ minutes. When at my home and breakers I can charge at 46 amps for hours with no issue.

Yes, although I suspect your issue was more due to an older, worn breaker. Loose lugs can indeed cause a breaker to get hotter and trip, because the heat can be transferred through the conductors to the breaker's inside mechanism; however, I have also seen many times where this doesn't happen well enough to cause tripping (and you'll see burned insulation on the wires attached to the breaker as they get extremely hot on loose lugs).

 

[Cottonwood]

"Few dollars" gets really expensive when you're talking a 100' to 200' of #2, #0, or even 2/0 run from a diesel genset to an indoor location. Just for reference, 2-2-2-4 copper cable runs about $7/ft while 2-2-2-4 AL cable runs about $1.75/ft.

I agree that copper is more money than aluminum, but to be fair, wouldn't you have to compare 2-2-2-4 copper with 0-0-0-2 aluminum, or 4-4-4-6 copper with 2-2-2-4 aluminum, for the same Amperage rating?

 

[FlasherZ]

I agree that copper is more money than aluminum, but to be fair, wouldn't you have to compare 2-2-2-4 copper with 0-0-0-2 aluminum, or 4-4-4-6 copper with 2-2-2-4 aluminum, for the same Amperage rating?

Sure, but it's still a giant difference. 3-3-3-5 is $6/ft; 4-4-4-6 copper isn't much less.

 

[islandbayy]

"Few dollars" gets really expensive when you're talking a 100' to 200' of #2, #0, or even 2/0 run from a diesel genset to an indoor location. Just for reference, 2-2-2-4 copper cable runs about $7/ft while 2-2-2-4 AL cable runs about $1.75/ft.

Many people hear horror stories about AL wire, but the context isn't given around it. The AL wire that caused plenty of problems in the 1970's was solid, smaller in-wall wiring similar to the Romex that you use today. The alloy that was used back then was susceptible to tensile strength failures and got brittle after many cycles of expansion and contraction (since copper and aluminum expand and contract at different rates). That wiring (and usually the junctions to other devices) was very problematic.

The AL wiring you get for larger gauge needs today is perfectly safe and acts very similar to copper. In addition, the bonding materials used to connect to AL wire in terminations are much safer than in the 1970's. In fact, while many electricians still insist on using an de-oxidant compound (NOALOX), it is NOT needed in most of today's terminations. UL standards call for testing without a deoxidizer first. Of course, this varies by product and jurisdiction. Some inspectors will require it anyway (although that is rare nowadays), even while most equipment doesn't require it. Adding it doesn't hurt, but you have to follow directions - some DIY'ers just apply the goo to the outside and don't follow the instructions to use a wire brush to work it into the conductor cable and remove oxidation.

For what it's worth, I don't use de-oxidizer on aluminum terminations. The most important element is to properly torque those connections - most people will under-torque the bolts, creating resistance. The proper torque spreads the cable and creates surface contact over a broader area - and you won't get that if you're just screwing it with a "soft hand tight" type approach.

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Yes, although I suspect your issue was more due to an older, worn breaker. Loose lugs can indeed cause a breaker to get hotter and trip, because the heat can be transferred through the conductors to the breaker's inside mechanism; however, I have also seen many times where this doesn't happen well enough to cause tripping (and you'll see burned insulation on the wires attached to the breaker as they get extremely hot on loose lugs).

I agree, copper is much more expensive when you are dealing with those gauges, also, dont forget to point out, Aluminum must be thicker to support the same amperages.

[EDIT] I should have hit submit on my post yesterday instead of forgetting it on my screen.....

 

[N4HHE]

In the Bad Old Days the problem with aluminum house wiring was that too many used the standard outlets and switches of the day with brass screw wire termination designed for copper. Bend a hook in the wire, wrap it around the screw, tighten. Brass and aluminum expand at different rates working the screws loose. Bad connection gets hot and works even looser. Eventually fire starts. A friend's parents had a 1970's vintage mobile home which was so wired. Outlets and switches routinely got hot. Wasn't practical to rewire so we replaced all the outlets and switches. Put an end to the problem.

Most modern outlets and switches are plainly labeled "Cu and Al". No longer use screws but a quicker and more reliable spring loaded press connection. Push the stripped lead in a hole and its gripped. If it expands and contracts with temperature thats OK because the spring will give and take and maintain connection.

This doesn't apply to big connectors such as a NEMA 14-50R.

 

[FlasherZ]

Most modern outlets and switches are plainly labeled "Cu and Al". No longer use screws but a quicker and more reliable spring loaded press connection. Push the stripped lead in a hole and its gripped. If it expands and contracts with temperature thats OK because the spring will give and take and maintain connection.

Just a quick public service announcement: while those spring-loaded press-in connections ("backstab") are considered quicker, they're certainly not more reliable. They're one of the primary reasons for intermittent outlet failures and burned wires in outlets. If you're looking for quick, get the kind that allow insertion of the straight stripped wire from the back of the outlet, and hold the wire in place by tighening the screws (called "backwired"). Avoid the push-in kind (although the project-house developers almost always use them).

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In the Bad Old Days the problem with aluminum house wiring was that too many used the standard outlets and switches of the day with brass screw wire termination designed for copper.

The issue was less with brass (as aluminum and brass share similar expansion rates), but more that steel replaced the brass in termination screws in the 1960's and 1970's. Couple this with the fact that the AA-1350 alloy being used was derived from long-haul high-tension electrical cables and didn't fit building wiring needs, and you experienced the faults that you did with differing expansion and creep rates.

Newer AA-8000 alloys (required since NEC 1987) act more like copper, and have similar mechanical characteristics to the terminations they're used in.

 

[CliffG]

I'll pay dollars to doughnuts the lugs are loose. Re-torque the connections and see if that fixes it, otherwise replace the breaker.

So, finally was able to address this - first, the lugs wouldn't tighten any further. Then, to cover all bases, replaced the breaker (yes, No-Ox applied, too). Charged for 2+ hours @ 40A/240V without incident.

So far, so good.

 

[Chipper]

So, finally was able to address this - first, the lugs wouldn't tighten any further. Then, to cover all bases, replaced the breaker (yes, No-Ox applied, too). Charged for 2+ hours @ 40A/240V without incident.

So far, so good.

I hope your good fortune continues to hold. Glad that it seems you might have it figured out!

 

[ToddRLockwood]

Yesterday my 240V circuit breaker popped after charging at 36 amps from 130 miles to 230 miles. Reset, then popped again at 251 miles. Service says it's my line but this did not occur 1st 3 months and is now happening more frequently. Is it my line or the UMC or adapter?

I experienced the same thing with a 50A breaker at a KOA RV campground. Even charging at 32A was enough to overload it. Clearly the breaker was worn out. If a 40A breaker gets hot to the touch or gives off an electrical odor while under a 30A load, you need to replace it.

 

[CliffG]

I hope your good fortune continues to hold. Glad that it seems you might have it figured out!

Thanks. In my mind, I owe the simple solution to the advice of the forum members. I just wanted to follow up with the outcome - it's common to find problems and proffered solutions online, but fewer outcomes. Hope this helps someone else down the line.

 

[andrewket]

Check your connections. It's possible over time they have become loose and its generating resistance and heat. The breaker may be fine. The problem is when you replace it you will also fix the loose connection, and you'll come to incorrect conclusion that he breaker was faulty.

 

[CliffG]

Check your connections. It's possible over time they have become lose and its generating resistance and heat. The breaker may be fine. The problem is when you replace it you will also fix the lose connection, and you'll come to incorrect conclusion that he breaker was faulty.

Indeed. Try the simplest option first. In my case, the connections weren't loose. I suppose reseating and retightening would have been a good next step, but didn't do it.