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Posted by Nate Nagel on April 23, 2008, 8:27 pm
RBM wrote:
>
>>On Apr 22, 10:59 pm, rajmada...@gmail.com 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
>
>
You'd know better than I; I've never installed one. Just the usual
fan-only deals, with a separate light on the wall.
nate
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
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