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RBM[_2_] RBM[_2_] is offline
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Default Rewiring a Vent/Heat/Light unit in bathroom


"N8N" wrote in message
...
On Apr 23, 9:07 am, N8N wrote:
On Apr 22, 10:59 pm, wrote:





Thanks Nate, RBM, and DerbyDad.


The fog is finally lifting. After sitting down and drawing the
solution with pen and paper I understand everyone’s suggestions. (BTW
Nate, the new unit does have four functions: Vent/Heat/Light and Night-
Light).


What I also understand now is what the original installer did and
“why” he did it. Basically, he wanted to keep the actual wire count
down in the switch box. Hence, instead of taking a Neutral from one
of 12/2 wires going from the switch to the unit, he ran a separate
Neutral wire directly to the unit from the source junction.


This approach might seem silly, but considering the shallowness of the
wall, he wasn’t able to put in a 2 gang deep box.


The one thing I do NOT like about his approach, was to keep the
grounding to only one wire (i.e. only one of the 12/2 wires going to
the unit is grounded, the other ground wire is cut). Theoretically,
the unit is grounded, but I agree with Nate’s remark, all the grounds
should be connected.


Raj


Only one ground wire is perfectly fine - you have a 20A circuit,
therefore if there is current to ground of over 20A the breaker will
trip. A single 12AWG conductor is sufficient to carry a 20A load.
Now if you have more than one ground, there's absolutely nothing wrong
with connecting them all together, just provides redundant paths.

What *isn't* fine is the multiple cables. think about it like this,
you'll have a single neutral going to the ceiling unit, but multiple
"hot" wires for different functions. The current in the neutral wire
will be the sum of all the currents in the "hot" wires, but in the
opposite direction. Code requires that the currents sum to zero in
every single cable assembly. otherwise you can get induced currents
and resultant heating, which isn't good. In practice this is probably
insignificant, but "probably" is not a good thing to rely on, and it's
against code.

it sounds like you may want to replace your wall switch box with a
three or four gang old work box to give you some more wiring space,
and either run some greenfield as RBM suggested, or else pull two
12/3wgs and split the neutrals apart at the device - e.g. run the
light and night light, say, off one cable and and have the neutrals
for those functions connected to the neutral in that cable, and then
have the fan and heater on another cable, with the neutrals for those
functions connected to the neutral in the second cable.

If you're replacing your wall box, you may want to consider adding a
GFCI outlet as well if the switches are near your sink. This is also
required by current code and is awful handy for hair dryers, electric
razors, etc.

Another thing you may want to think about while you're doing all these
mods is running the vent fan off of a timer switch rather than a
regular toggle switch, that way you can set it to run on for 15 min.
or whatever after you get out of the shower and you don't have to
remember to turn it off later (or have to turn it off earlier than
you'd otherwise want to if you shower and then immediately leave the
house for the day.)

I'd consider using all Decora devices in this instance as that will
allow you more flexibility in mixing and matching stuff, and two- and
three-switch devices are available in Decora format as well if
necessary.

good luck,

nate


One last thought - if the new location of the fan is above the shower,
you should connect the feed for the switches controlling all this
stuff from the "load" terminals of the GFCI recep unless you have a
GFCI breaker in your panel. If you do have a GFCI breaker and still
want to add a recep you can just use a regular one, there would be no
point in using a GFCI on a circuit that's already protected.

nate

These units, having a 1.5 kw heating alone, require a dedicated 20 amp
circuit. If it's located over the tub or shower, it is required to be gfci
protected, but can't be on the same circuit as the required gfci outlet for
the hair dryer