Neutrals in parallel
- Thread starter domnic
- Start date
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
J box 2 circuits or more and tied all neutrals together, you will have parallel neutrals back to panel. Seen many times. Issue that all neutrals will be energized when only one circuit turned off. Lights are off but you will still have current potential on the neutral.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yes, but that is an illegal hookup. One problem with parallel neutrals is if the installation did not follow code and one conductor was longer than another.
@domnic Are you talking about larger conductors like 1/0 and larger?
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
Illegal but extremally common in an area that doesn't have license requirements, that GC and handymen do their own thing and have never opened a code book, no permits and no inspections.
If i have a # 3 thhn and a # 6 thhn neutral from the meter base to the 100 amp panel . other than double lugging , what is the problem ?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Where is the double lugging. You have a neutral (#6) and 2 hots (#3)---Is that correct? You really need to explain further. You are giving little bits of info but not enough to know what you mean. You cannot parallel wires smaller than 1/0 so I am not sure where the title fits here.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
We need to know whether you're asking about intentional or inadvertent paralleling.
ptonsparky
Tom
- Occupation
- EC - retired
I think he means he has both a #3 & #6 going to the meter base neutral lug. Double lugged. Two in a hole.
The world will come to an end tomorrow at 6:23 AM
It's not supposed to be done. Someone didn't know better most likely.
The world will come to an end tomorrow at 6:23 AM
It's not supposed to be done. Someone didn't know better most likely.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
It's 6:43 and all is fine!
WHY ????????????????????????????????????????????????
ptonsparky
Tom
- Occupation
- EC - retired
Dang. Wrong again.
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
Are both neutrals? If yes, the problem is a difference in resistance between the 2 different conductors forcing a larger load onto one of the conductors creating an imbalance, and potentially overloading one conductor. Also a code violation Each conductor of the parallel must be capable of carrying the full imbalance load imposed.
Review 310.10(G)(1)(2)
Wire sizes given and in combo with 100A OCD sounds as if you got 1 neutral 1 EGC not 2 Neutrals. That is not parallel unless you are N/G bonded at both ends. Then you have another code violation.
ptonsparky
Tom
- Occupation
- EC - retired
Is it likely to cause a mechanical or electrical problem at typical load of the #3, No.
A 200 amp load on the two in parallel would result in about 133 on the #3 and 66 on the #6. Using table 9 for DC values of resistance.
A 200 amp load on the two in parallel would result in about 133 on the #3 and 66 on the #6. Using table 9 for DC values of resistance.
ptonsparky
Tom
- Occupation
- EC - retired
Maybe someone needs to check my math.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
The code does not allow wires smaller than 1/0 to be paralleled.
More than 1 wire in a lug designed for 2 wires.
Can't use THHN into an outdoor meter, needs to be THWN or XHHW etc
YOU are side stepping the Queston !!
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If you have 2 different sizes the damage could be that one conductor will carry most of the load and possibly overload. When the conductors are that short it may not be an issue anyway since the neutral load is usually much less than the phase loads.
Why is it illegal to use sizes under 1/0? I don't know... I assume because those size wires are usually available so no need to parallel a 100 amp load when a #3 or #2 can handle it.
Why is it illegal to use sizes under 1/0? I don't know... I assume because those size wires are usually available so no need to parallel a 100 amp load when a #3 or #2 can handle it.