Shared neutral lighting
- Thread starter jkrauss
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bobbymari
Senior Member
- Location
- los angeles ca
yes its required 210.4(b) and its ALL multiwire branch circuits not just lighting as of 2008 code. In the near future I suspect a new requirement of dedicated nuetrals for every circuit but that hasn't happend yet
Last edited:
grasfulls
Always tired, so cannot retire
- Location
- Placer County. CA
- Occupation
- Professional inane question maker
AFCI and shared neutrals
AFCI and shared neutrals
With the mandate for AFCI on new construction residential, shared neutrals should disappear. They are such a troubleshooting issue anyway.
AFCI and shared neutrals
With the mandate for AFCI on new construction residential, shared neutrals should disappear. They are such a troubleshooting issue anyway.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
grasfulls
Always tired, so cannot retire
- Location
- Placer County. CA
- Occupation
- Professional inane question maker
A/A Fuel GTX
Senior Member
- Location
- WI & AZ
- Occupation
- Electrician
They are fine if installed properly. It's when unqualified fingers get into them and screw things up, when the problems begin.
I agree. I find it funny how there is continuing efforts to dumb things down but, the NFPA and OSHA feel it's neccessary to have a definition of Qualified Person.
Roger
spark master
Senior Member
- Location
- cyberspace
Then in effect, are you saying when I look in a commercial panel, every breaker should be a 3 pole breaker ?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The subject is MWBCs.
Not necessary when separate neutrals are used for wye load circuits. So you can't tell without a deeper look.
If single phase phase-to-phase loads are used, you could have a whole lot of two pole breakers.
spark master
Senior Member
- Location
- cyberspace
But if I'm putting in 3 rows of 120v lighting, you know I'm only pulling 1 neutral. Otherwise the conduit is getting larger. And if someone does a new build, you know they are sharing neutrals. Therefore, your expecting to see all 3 pole breakers. Which means one shorted ballast will make the whole floor dark. You see what I'm getting at.
Pretty much everyone sees what you are getting at :happyyes: unless they are in the dark
.FWIW, three 1P breakers with handle tie is not the same as a common trip 3P breaker. The handle tie is not an assurance that all breakers will be deenergized when one trips... but there is a definite possibility of that occuring....
...and the only sure way of preventing that is to run individual circuits.
- Location
- Illinois
- Occupation
- retired electrician
If the voltage to ground does not exceed 120 volts, handle ties are acceptable for single phase line to line loads....most of the time a two pole breaker is used, but the code does not require that.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Actually all breakers today are of the trip free type and handle ties will not cause the other breakers to open, the problem is always finding handle ties available, as for this purpose I would believe that 3 single pole breakers would be a lower cost then to use three pole common trip breakers. I know Square D has handle tie kits at most supply houses, even Menard's caries them but only for up to two handles not three.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The minimum code requirement is only for handle ties, since the goal is to make sure the neutral is not carrying current when you are going to work on luminaires connected to only one phase. It is perfectly fine to have individual phase or fixture run switches downstream, since the disconnect will still affect all phases. Even the handle ties without common trip will cause maintenance headaches. (But headaches do not justify live work.)Pretty much everyone sees what you are getting at :happyyes: unless they are in the dark
FWIW, three 1P breakers with handle tie is not the same as a common trip 3P breaker. The handle tie is not an assurance that all breakers will be deenergized when one trips... but there is a definite possibility of that occuring....
...and the only sure way of preventing that is to run individual circuits.
The common commercial situation in which the CBs are used for routine switching of the lighting circuits gets very painful with handle ties, but then again so does having to wear PPE to turn the lights on and off (separate thread.)
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
How can the code require that on circuits over 150 volts to ground if we are allowed to use fuses? I never understood this:roll:
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
How about that the fuses are not going to be used as disconnects?
In a situation where actual common trip is required, then fuses do seem inappropriate.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
In Don's post it seen he indicated that common trip was required for single phase MWBC's where the voltage is above 150 volts to ground?, I know there are some codes that do require common trip like autotransformer's, in 450.5(B)(2)(a)
And 647.4 are two locations that I know of, and the latter even allows fuses which doesn't make sense to me.
But I don't know anywhere the code requires a common trip just because the voltage to ground is higher then 150 volts??
wirebender
Senior Member
- Location
- North Central Texas
Don said line to line loads.
240.15
(B) Circuit Breaker as Overcurrent Device. Circuit
breakers shall open all ungrounded conductors of the circuit
both manually and automatically unless otherwise permitted
in 240.15(B)(1), (B)(2), (B)(3), and (B)(4).
...
(2) Grounded Single-Phase Alternating-Current Circuits.
In grounded systems, individual single-pole circuit
breakers rated 120/240 volts ac, with identified handle ties,
shall be permitted as the protection for each ungrounded
conductor for line-to-line connected loads for single-phase
circuits.
(3) 3-Phase and 2-Phase Systems. For line-to-line loads
in 4-wire, 3-phase systems or 5-wire, 2-phase systems, individual
single-pole circuit breakers rated 120/240 volts ac
with identified handle ties shall be permitted as the protection
for each ungrounded conductor, if the systems have a
grounded neutral point and the voltage to ground does not
exceed 120 volts.
...
wirebender
Senior Member
- Location
- North Central Texas
We just finished a project that disallowed the use of MWBCs.
The office section had over one hundred separate 120V circuits.
I was tired of landing neutrals after the first panel.
spark master
Senior Member
- Location
- cyberspace
Don't you loose efficiency when not sharing neutrals ?
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