I work for a co. that does service work. I talked to a licensed wireman who told me he was on a call yesterday and he had to put a new breaker in a 60amp, single phase panel that only had 6 breakers in it. He told me there was a doghnut shaped device that had all the branch circuit wires running through the center of it. The doghnut device had 2 wires that were connected to it that he said left out of the bottom of the panel. He cut the 2 wires, removed the doghnut, and then landed those 2 wires on the neutral bus. I told him I think he removed a control transformer, but have only seen them used on large commercial panels so Im not sure what he did. He is going to ask our boss tommorow, but I was just curious what exactlly that device he took out was. Any ideas?
Doghnut in residential panel?
- Thread starter nec4me
- Start date
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hbiss
EC, New York NEC: 2017
- Location
- Little Falls, New York NEC: 2017
- Occupation
- EC
Re: Doghnut in residential panel?
Sounds like a current sensing coil for maybe submetering equipment. Was this a unit in a multifamily complex? Why did he remove it? If it was being used you guys will hear about it I'm sure!
-Hal
Sounds like a current sensing coil for maybe submetering equipment. Was this a unit in a multifamily complex? Why did he remove it? If it was being used you guys will hear about it I'm sure!
-Hal
Re: Doghnut in residential panel?
Its a condominium and he said he removed it because the two wires that left the sensor were green and the two wires it connected to were white. So he said he figured the 2 white wires should be on the neutral bus. I'm like you, why did he even remove it? At the shop he had the sensor in his hand and I asked him why he removed it and he didn't answer me, he just kept looking at it like it was a moon rock or something.
One more thing is he said that both the hots and grounded conductors went through the sensor. How could that be? Wouldn't the magnetic fields cancel each other out and the sensor wouldn't read anything? Could it be that he was mistaken and only the hots went through the sensor? Thanks.
[ October 05, 2004, 08:39 PM: Message edited by: nec4me ]
Its a condominium and he said he removed it because the two wires that left the sensor were green and the two wires it connected to were white. So he said he figured the 2 white wires should be on the neutral bus. I'm like you, why did he even remove it? At the shop he had the sensor in his hand and I asked him why he removed it and he didn't answer me, he just kept looking at it like it was a moon rock or something.
One more thing is he said that both the hots and grounded conductors went through the sensor. How could that be? Wouldn't the magnetic fields cancel each other out and the sensor wouldn't read anything? Could it be that he was mistaken and only the hots went through the sensor? Thanks.
[ October 05, 2004, 08:39 PM: Message edited by: nec4me ]
charlie
Senior Member
- Location
- Indianapolis
Re: Doghnut in residential panel?
I am guessing that this is a current transformer and that it is feeding an electric utility meter that is gathering data for some purpose. We have done this and will continue to do it on an as needed basis to determine demand on certain equipment. Other electric utilities will do the same thing for various purposes. I suspect you have just cost the homeowner some predetermined fee that would be paid for permitting this installation.
I am guessing that this is a current transformer and that it is feeding an electric utility meter that is gathering data for some purpose. We have done this and will continue to do it on an as needed basis to determine demand on certain equipment. Other electric utilities will do the same thing for various purposes. I suspect you have just cost the homeowner some predetermined fee that would be paid for permitting this installation.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Doghnut in residential panel?
It is a CT transformer.Posibly to read that units electric bill.Why would he remove something he knowed nothing about ? Your boss will have a headache over this one.Keep us informed.
It is a CT transformer.Posibly to read that units electric bill.Why would he remove something he knowed nothing about ? Your boss will have a headache over this one.Keep us informed.
Re: Doghnut in residential panel?
Steve
Usually with one hot wire and one neutral wire (or 2 hot wires) they are fed through the doughnut in different directions so the magnetic fields add. I guess the same principle could be extended to 4 wires.
Steve
Re: Doghnut in residential panel?
This sounded like a ct for metering power usage at first,but the doughnut should have been placed on the feeder wiring to the panel not the branch circuits.I'm not convinced this is a ct doughnut used for metering power usage.I'm anxious to hear what it was.If it was a ct for metering power usage,they are putting a lot of faith in the installer running the branch circuits through the doughnut each time.You can't run (2) different phase conductors throught the same doughnut,(a&b)If the neutrals are also passing through the doughnut,I think its something else,probably a ground fault sensor or the like.
[ October 06, 2004, 11:42 AM: Message edited by: jap2525 ]
This sounded like a ct for metering power usage at first,but the doughnut should have been placed on the feeder wiring to the panel not the branch circuits.I'm not convinced this is a ct doughnut used for metering power usage.I'm anxious to hear what it was.If it was a ct for metering power usage,they are putting a lot of faith in the installer running the branch circuits through the doughnut each time.You can't run (2) different phase conductors throught the same doughnut,(a&b)If the neutrals are also passing through the doughnut,I think its something else,probably a ground fault sensor or the like.
[ October 06, 2004, 11:42 AM: Message edited by: jap2525 ]
Re: Doghnut in residential panel?
It could be a ground fault detector, but here in the midwest, we get a discount for any electricity used for heating. The power co. provides a doughnut CT, and the two hot wires (for the 240V heating) are both wrapped once around the CT (in opposite directions). The doughnut then feeds a second meter. When the POCO then gives a discount for the amount of electricity that shows up on the 2nd meter.
That sounds a lot like this doughnut.
Steve
It could be a ground fault detector, but here in the midwest, we get a discount for any electricity used for heating. The power co. provides a doughnut CT, and the two hot wires (for the 240V heating) are both wrapped once around the CT (in opposite directions). The doughnut then feeds a second meter. When the POCO then gives a discount for the amount of electricity that shows up on the 2nd meter.
That sounds a lot like this doughnut.
Steve
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Doghnut in residential panel?
Why did he even mess with this CT? How did he remove it without taking all the wires loose ? Does he still have a job today ? If it was a gfci it would need 2 coils to detect the fault
Why did he even mess with this CT? How did he remove it without taking all the wires loose ? Does he still have a job today ? If it was a gfci it would need 2 coils to detect the fault
- Location
- Massachusetts
Re: Doghnut in residential panel?
LOL
Re: Doghnut in residential panel?
I didnt get to go on the call with him, but was told that he and a J-man went out and re-installed the sensor. He said that only the branch circuit hot wires went through the sensor and not the grounded conductors. He also said the j-man traced the wires and they went to a meter base. Guess he wont be removing any of more those.
I didnt get to go on the call with him, but was told that he and a J-man went out and re-installed the sensor. He said that only the branch circuit hot wires went through the sensor and not the grounded conductors. He also said the j-man traced the wires and they went to a meter base. Guess he wont be removing any of more those.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Doghnut in residential panel?
should he be doing service calls alone ?
should he be doing service calls alone ?
charlie
Senior Member
- Location
- Indianapolis
Re: Doghnut in residential panel?
Jim, I think that is the best question anyone of us has asked.
Jim, I think that is the best question anyone of us has asked.
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