hde_electric
Member
How do you find the neutral current in a single phase system(Residential)?
How do you find neutral current in a single phase system
- Thread starter hde_electric
- Start date
- Status
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: How do you find neutral current in a single phase system
Its the unbalanced load between the L1 and L2.
Its the unbalanced load between the L1 and L2.
hde_electric
Member
Re: How do you find neutral current in a single phase system
What do you mean by an unbalanced load how do you find this?
What do you mean by an unbalanced load how do you find this?
Ed MacLaren
Senior Member
Re: How do you find neutral current in a single phase system
Use your clamp-on ammeter. :roll:
Use your clamp-on ammeter. :roll:
hde_electric
Member
Re: How do you find neutral current in a single phase system
If I have 50 amps on L1 and 40 amps on L2 will the unbalanced load be 10 amps on the neutral line?
If I have 50 amps on L1 and 40 amps on L2 will the unbalanced load be 10 amps on the neutral line?
charlie
Senior Member
- Location
- Indianapolis
Re: How do you find neutral current in a single phase system
Refer to 220.22 which states "The maximum unbalanced load shall be the maximum net computed load between the neutral and any one ungrounded conductor"
I am curious though, are you an electrician?
Refer to 220.22 which states "The maximum unbalanced load shall be the maximum net computed load between the neutral and any one ungrounded conductor"
I am curious though, are you an electrician?
hde_electric
Member
Re: How do you find neutral current in a single phase system
My question is how do you know what your unbalanced load is.
I am an apprentice electrician.
My question is how do you know what your unbalanced load is.
I am an apprentice electrician.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: How do you find neutral current in a single phase system
The unbalanced current on a single phase system is determined by subtracting the amperage on L1 from the amperage on Line 2. In the most extreme unbalance one of the lines will have zero current, so the neutral current will be equal to the remaining line.
Examples:
L1-L2=N
40A-25A=15A
17A-93A=76A
0A-200A=200A
The unbalanced current on a single phase system is determined by subtracting the amperage on L1 from the amperage on Line 2. In the most extreme unbalance one of the lines will have zero current, so the neutral current will be equal to the remaining line.
Examples:
L1-L2=N
40A-25A=15A
17A-93A=76A
0A-200A=200A
karl riley
Senior Member
Re: How do you find neutral current in a single phase system
If you clamp your ammeter around both hots, the reading is the unbalance. The neutral should be carrying this amount of current. To double check, clamp around all three. The meter should read zero. If not, some neutral current has been diverted and you may have a Code violation.
Karl
If you clamp your ammeter around both hots, the reading is the unbalance. The neutral should be carrying this amount of current. To double check, clamp around all three. The meter should read zero. If not, some neutral current has been diverted and you may have a Code violation.
Karl
pierre
Senior Member
- Location
- Westchester County, New York
Re: How do you find neutral current in a single phase system
Karl
I have never heard that before, sometimes the simple ideas can go right by us. Thanks, this can be very useful info.
Pierre
Karl
I have never heard that before, sometimes the simple ideas can go right by us. Thanks, this can be very useful info.
Pierre
karl riley
Senior Member
Re: How do you find neutral current in a single phase system
Yes, it works for 3 phase, and two phase also. The resultant is always zero for all hots plus neutral. This is how I trace circuits with missing neutral (or too much neutral - from another circuit).
I think that the usual instruction to use clamp-ons only on single conductors missed out on some other uses of the clamp-on.
Karl
Yes, it works for 3 phase, and two phase also. The resultant is always zero for all hots plus neutral. This is how I trace circuits with missing neutral (or too much neutral - from another circuit).
I think that the usual instruction to use clamp-ons only on single conductors missed out on some other uses of the clamp-on.
Karl
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: How do you find neutral current in a single phase system
Karl...Great info. I could have used this two nights ago!!!
Karl...Great info. I could have used this two nights ago!!!
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: How do you find neutral current in a single phase system
The CT around all the hots and the neutral is one way GFI activation is determined for some systems.
The CT around all the hots and the neutral is one way GFI activation is determined for some systems.
G
Guest
Guest
Re: How do you find neutral current in a single phase system
Useful picture. It may time out soon. May not be a permanent link to MikeHolt.com
It's called Neutral Current on Multi-Wire Circuits
../Wayne
Useful picture. It may time out soon. May not be a permanent link to MikeHolt.com
It's called Neutral Current on Multi-Wire Circuits
../Wayne
karl riley
Senior Member
Re: How do you find neutral current in a single phase system
Wayne, that brings up another use of the clamp-on. If you find a suspicious circuit you can clamp around the individual conductors and then around pairs. This will tell you if you have two L-1s together. Also, sometimes the wrong neutral is run with a hot, so comparing individual readings with pairs shows you when you have a neutral with the wrong phase (from another circuit). It adds instead of subtracts. Two-phase is fun too.
Recently I clamped around a romex. Zero, as it should be. But when I clamped around the hot it was zero, the neutral was 4.18A, and the EGC was 4.18A. Obviously the neutral and ground were at oposite phase angles since they read zero together. So the only logical answer was that the neutral ran down the cable to where it was connected to the grounding conductor, which then brought it back to (in this case) the junction box, then building steel, then a copper pipe, and back to the Tformer. Fun and games with a clamp-on. (Need a mini for some of this).
Karl
Wayne, that brings up another use of the clamp-on. If you find a suspicious circuit you can clamp around the individual conductors and then around pairs. This will tell you if you have two L-1s together. Also, sometimes the wrong neutral is run with a hot, so comparing individual readings with pairs shows you when you have a neutral with the wrong phase (from another circuit). It adds instead of subtracts. Two-phase is fun too.
Recently I clamped around a romex. Zero, as it should be. But when I clamped around the hot it was zero, the neutral was 4.18A, and the EGC was 4.18A. Obviously the neutral and ground were at oposite phase angles since they read zero together. So the only logical answer was that the neutral ran down the cable to where it was connected to the grounding conductor, which then brought it back to (in this case) the junction box, then building steel, then a copper pipe, and back to the Tformer. Fun and games with a clamp-on. (Need a mini for some of this).
Karl
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