Ceiling Fan has one neutral ( white wire) for both fan and light.
Light has blue wire.
Fan motor has black wire.
Box where fan is being hooked up has lighting circuit for light switch on
one circuit from main circuit breaker panel and fan motor feed coming from
sub panel on another circuit.
Which neutral should be hooked up to fan's white wire?
Do both the feed for the fan motor and the feed for the light that is
on a seperate panel come into the same box that is going to be the
single control box for the fan and the light? A box that has switches
for the fan and the light? If so, why the need for seperate
circuits? Just feed the fan and the light off one branch circuit and
don't use the other circuit.
If the fan control and the light control are in seperate boxes that
are physically seperate, then I don't know what you do with the fact
that you have two seperate neutrals coming to the fan from two
separate branch circuits and only one neutral connection at the fan.
Another option is to wire the fan/light using a remote control, which
can also be left in a wall holster. In that case you;d also use only
one branch circuit and wire it so the circuit to the fan/remote module
is always live.
Like it or not, I think you should "undo" the previous wiring UNLESS the fan
you intend to use can be rewired to separate the motor neutral from the
If you just have conventional CBs or fuses, it will work regardless of which
neutral you use but the "hot" and the associated neutral are supposed to
stay in the same cable.
Indeed, each cable regardless of use should carry ZERO net current. That
means the "return" current is the same as the load current. Unless you
have some kind of leakage to ground, proper wiring always ensures this will
be the case. It's even true with cables that only serve a switch and 3/4
way switch arrangements.
But that's mostly a theoritical concern. What might cause "complicated"
problem would be if someone "for safety's sake" replaces on or the other
breaker serving your fan with a GFCI breaker. The odds are great that the
mixed or combined neutrals on single pole circuits will cause all kinds of
false trip problems.
Agree with all the above and there are no odds about a GFCI breaker
tripping under those conditions, unless you mean 100%. If you just
used one circuit neutral or the other or combined them, it will trip
as soon as the fan or light, whichever is on the GFCI is turned on.
Is there a reasonable way to run a cable from the light switch
location to the fan switch location?
I can see how that would happen. I'm guessing the supply line for the
multiple switches is not in the box where he wanted the fan switch.
The simplest solution to correct the problem code-wise would be to use
the "new" supply line for both the light and fan. I believe you
should have enough 14/3 between the switches to do this. Just cut off
the original suply in what ever box it's in after you are done. Plan
your new 3 way wiring before starting. Based on what you told us I
believe you can move it all to the new circuit without pulling any wre.
You really do need to have both loads on the same circuit. Let me
suggest that you figure out which box is easier to get the power from
and pull a two wire cable from that box to the fan support box. That
cable will supply the power for both fan and light. You then rewire
the existing switching circuits to make use of the new power source
location. If it turns out to be easier you could replace the cable
from the fan control point with a three wire cable so that it will
bring both switched and constant power to the fan support box. You
then wire the three and four way switching circuit to take advantage
of the power supply from that new cable. If any of that is unclear
then just ask questions. No one was born knowing this stuff and we
all had to start someplace.
Disassemble the fan enough to locate where the light return is joined
onto the motor return, separate them there and add another "white"
return so that the light and the motor now each have their own return leads.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.