jaylectricity
Senior Member
- Location
- Massachusetts
- Occupation
- licensed journeyman electrician
120/240v single phase service. I'm troubleshooting several tripping breakers for a new install. All wiring is new including the service. I'm told about 3 breakers that are tripping. An SABC, a bathroom receptacle circuit, and a living room receptacle and lighting circuit.
Short story:
After playing around with various things I realize that one issue is just an overcurrent issue. But the other issue is that some AFCI breakers on one phase will trip. But if I move the breaker to the other phase it holds. Is this something common? I originally thought the issue was the newer Siemens arc-fault breakers that don't require the neutral to be landed on them. I thought maybe they hadn't "perfected" the technology, much like how when they were forced on us at the beginning of the century to be field tested before they had figured out how to make them right.
I unplugged an old printer and the circuit held. If I brought it to another circuit on the same phase it tripped the breaker. If I plugged it in to a circuit on the other phase it did not.
This customer is not going to accept that things work because I'm keeping certain things away from a phase. But I don't know of any reason why it trips one phase and not the other. Voltage on each leg is within .1% of each other with the usual variations the longer I hold the tester on them.
Longer story/more info
When I arrive we try to recreate the SABC problem by running his air-fryer and and the water heater function in his fridge.1 This should trip the breaker, it does not. He says he's been using those regularly for a week or so and Saturday was the first time there was a problem. We couldn't recreate the problem. Sounds more like an overcurrent problem. The air-fryer name plate was 1760W. Fridge's nameplate was kind of confusing. I assume a small heating element draws a bit...maybe if the compressor is also running it trips the breaker.
We aren't able to recreate the bathroom problem. He says they were using a hair dryer. We ran both hair dryers they had and the breakers held. I looked and one of them was only 500W and the other was 1300W or so.
We are able to recreate the living room. After plugging and unplugging various items I narrowed it down to an older plasma tv. But it only tripped the breaker on that circuit. But that circuit only tripped when that tv was plugged in. I switched the conductor on that breaker with the conductor on an identical breaker just below it. Siemens plug-on AFCI that don't require the circuit's neutral to be landed on the breaker. Then it held.
Things were ok for a day until I get a text this morning that it's happening again. This time I buy a brand new clamp-on amp meter because the one I have has been acting weird. I get there and pretty much determine he's going to have to plug in his air-fryer on a different SABC. I'm starting to be convinced that the new type of plug-on breaker from Siemens may not have been perfected so I change the breaker for the bathroom circuit to one with a pigtail. That does the trick.
But now his office equipment in the guest bedroom is tripping. I isolate it down to his old printer. Again I find that it's tripping a breaker on the same phase as the living room breaker was. I plug the printer into another circuit on the same phase, it trips. I plug it into the living room (where I had switched phases) and it held.
A lot of the breakers that are on the affected phase are either regular breakers (outdoor plugs, utility room, garage) or 2-pole breakers.
He's wondering if we didn't torque the feeders right or if it's a loose connection at the street or something. I'm wondering if it's a POCO problem since it just started happening. We're pretty consistent with our torquing, but I suppose if we messed up it could be fine for a week or so until additional heat makes the problem more noticeable.
I just don't understand how that would affect an arc-fault breaker that's monitoring things downstream.
1. The fridge is on one of three SABC circuits. I did not know his fridge's water dispenser would heat the water up for tea
Short story:
After playing around with various things I realize that one issue is just an overcurrent issue. But the other issue is that some AFCI breakers on one phase will trip. But if I move the breaker to the other phase it holds. Is this something common? I originally thought the issue was the newer Siemens arc-fault breakers that don't require the neutral to be landed on them. I thought maybe they hadn't "perfected" the technology, much like how when they were forced on us at the beginning of the century to be field tested before they had figured out how to make them right.
I unplugged an old printer and the circuit held. If I brought it to another circuit on the same phase it tripped the breaker. If I plugged it in to a circuit on the other phase it did not.
This customer is not going to accept that things work because I'm keeping certain things away from a phase. But I don't know of any reason why it trips one phase and not the other. Voltage on each leg is within .1% of each other with the usual variations the longer I hold the tester on them.
Longer story/more info
When I arrive we try to recreate the SABC problem by running his air-fryer and and the water heater function in his fridge.1 This should trip the breaker, it does not. He says he's been using those regularly for a week or so and Saturday was the first time there was a problem. We couldn't recreate the problem. Sounds more like an overcurrent problem. The air-fryer name plate was 1760W. Fridge's nameplate was kind of confusing. I assume a small heating element draws a bit...maybe if the compressor is also running it trips the breaker.
We aren't able to recreate the bathroom problem. He says they were using a hair dryer. We ran both hair dryers they had and the breakers held. I looked and one of them was only 500W and the other was 1300W or so.
We are able to recreate the living room. After plugging and unplugging various items I narrowed it down to an older plasma tv. But it only tripped the breaker on that circuit. But that circuit only tripped when that tv was plugged in. I switched the conductor on that breaker with the conductor on an identical breaker just below it. Siemens plug-on AFCI that don't require the circuit's neutral to be landed on the breaker. Then it held.
Things were ok for a day until I get a text this morning that it's happening again. This time I buy a brand new clamp-on amp meter because the one I have has been acting weird. I get there and pretty much determine he's going to have to plug in his air-fryer on a different SABC. I'm starting to be convinced that the new type of plug-on breaker from Siemens may not have been perfected so I change the breaker for the bathroom circuit to one with a pigtail. That does the trick.
But now his office equipment in the guest bedroom is tripping. I isolate it down to his old printer. Again I find that it's tripping a breaker on the same phase as the living room breaker was. I plug the printer into another circuit on the same phase, it trips. I plug it into the living room (where I had switched phases) and it held.
A lot of the breakers that are on the affected phase are either regular breakers (outdoor plugs, utility room, garage) or 2-pole breakers.
He's wondering if we didn't torque the feeders right or if it's a loose connection at the street or something. I'm wondering if it's a POCO problem since it just started happening. We're pretty consistent with our torquing, but I suppose if we messed up it could be fine for a week or so until additional heat makes the problem more noticeable.
I just don't understand how that would affect an arc-fault breaker that's monitoring things downstream.
1. The fridge is on one of three SABC circuits. I did not know his fridge's water dispenser would heat the water up for tea
