Rewiring a Vent/Heat/Light unit in bathroom
 

I'm in the process of replacing an existing Vent/Heat/Light unit in my
bathroom. The old wiring setup on this system seems odd to me.

The previous installer is running three Romex wires to the unit.
There is a two gang switch controlling (with one double switch).
One wire holds the Neutral and ground (other wire is clipped), coming
from source junction box.
Another wire is holding two feeds from the switch (the ground is
clipped).
The last wire is holding one feed from the switch (the other wires
are clipped).

Here is my question:
Due to new location of the new unit, and existing cable size, I need
to extend the two feed Romex cables coming from the switch. Hence, I
need a junction box to extend the lines. The issue is, if I use a
metal box then shouldn’t those wires be grounded to the box?
Normally, I would say yes ground the wires to the box. However, the
previous installer cut the grounds on those cables… so what value
would there be in grounding them? Another solution is to use a
plastic junction box (which is legal in my town), to avoid the
grounding issue.

Any thoughts?

Thanks,
Raj

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 22, 1:12*pm, wrote:
I'm in the process of replacing an existing Vent/Heat/Light unit in my
bathroom. *The old wiring setup on this system seems odd to me.

The previous installer is running three Romex wires to the unit.
There is a two gang switch controlling (with one double switch).
* * * * One wire holds the Neutral and ground (other wire is clipped), coming
from source junction box.
* * * * Another wire is holding two feeds from the switch (the ground is
clipped).
* * * * The last wire is holding one feed from the switch (the other wires
are clipped).

Here is my question:
* * * * Due to new location of the new unit, and existing cable size, I need
to extend the two feed Romex cables coming from the switch. *Hence, I
need a junction box to extend the lines. *The issue is, if I use a
metal box then shouldn’t those wires be grounded to the box?
Normally, I would say yes ground the wires to the box. *However, the
previous installer cut the grounds on those cables… so what value
would there be in grounding them? *Another solution is to use a
plastic junction box (which is legal in my town), to avoid the
grounding issue.

Any thoughts?

Thanks,
Raj

"The old wiring setup on this system seems odd to me."

Is it possible to eliminate the existing (and bizarre) wiring and do
it correctly?

I would seem to me that this is the perfect time to correct a bad
wiring installation instead of simply extending it.

WWALED? (What would a licensed electrician do?)

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 22, 1:12*pm, wrote:
I'm in the process of replacing an existing Vent/Heat/Light unit in my
bathroom. *The old wiring setup on this system seems odd to me.

The previous installer is running three Romex wires to the unit.
There is a two gang switch controlling (with one double switch).
* * * * One wire holds the Neutral and ground (other wire is clipped), coming
from source junction box.
* * * * Another wire is holding two feeds from the switch (the ground is
clipped).
* * * * The last wire is holding one feed from the switch (the other wires
are clipped).

Here is my question:
* * * * Due to new location of the new unit, and existing cable size, I need
to extend the two feed Romex cables coming from the switch. *Hence, I
need a junction box to extend the lines. *The issue is, if I use a
metal box then shouldn’t those wires be grounded to the box?
Normally, I would say yes ground the wires to the box. *However, the
previous installer cut the grounds on those cables… so what value
would there be in grounding them? *Another solution is to use a
plastic junction box (which is legal in my town), to avoid the
grounding issue.

Any thoughts?

Thanks,
Raj

The whole thing is incorrect, you should be running one cable from the
switch box to the unit. Since that is not possible given that you
have three different functions in the unit (unless someone makes a
12/4wg cable?) that is, vent, heat, and light, do any of these
functions have their own neutral? If that is the case then you should
run a separate cable for the light, say, as a 12/2 w/ground, and then
another cable 12/3 w/ground for the vent and heat. Neutrals should be
connected to each other at the switch box but NOT in the v/h/l unit.
this way the currents in each cable will sum to zero in the absence of
a ground fault. All grounds should be connected together and to the
box at all locations.

You will have to run new wire from the switch box to the new location
to be code compliant.

good luck

nate

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 22, 2:43*pm, N8N wrote:
On Apr 22, 1:12*pm, wrote:





I'm in the process of replacing an existing Vent/Heat/Light unit in my
bathroom. *The old wiring setup on this system seems odd to me.

The previous installer is running three Romex wires to the unit.
There is a two gang switch controlling (with one double switch).
* * * * One wire holds the Neutral and ground (other wire is clipped), coming
from source junction box.
* * * * Another wire is holding two feeds from the switch (the ground is
clipped).
* * * * The last wire is holding one feed from the switch (the other wires
are clipped).

Here is my question:
* * * * Due to new location of the new unit, and existing cable size, I need
to extend the two feed Romex cables coming from the switch. *Hence, I
need a junction box to extend the lines. *The issue is, if I use a
metal box then shouldn’t those wires be grounded to the box?
Normally, I would say yes ground the wires to the box. *However, the
previous installer cut the grounds on those cables… so what value
would there be in grounding them? *Another solution is to use a
plastic junction box (which is legal in my town), to avoid the
grounding issue.

Any thoughts?

Thanks,
Raj

The whole thing is incorrect, you should be running one cable from the
switch box to the unit. *Since that is not possible given that you
have three different functions in the unit (unless someone makes a
12/4wg cable?) that is, vent, heat, and light, do any of these
functions have their own neutral? *If that is the case then you should
run a separate cable for the light, say, as a 12/2 w/ground, and then
another cable 12/3 w/ground for the vent and heat. *Neutrals should be
connected to each other at the switch box but NOT in the v/h/l unit.
this way the currents in each cable will sum to zero in the absence of
a ground fault. *All grounds should be connected together and to the
box at all locations.

You will have to run new wire from the switch box to the new location
to be code compliant.

good luck

nate- Hide quoted text -

- Show quoted text -

What N8N describes is essentially what I did, except that there are 2
additional lights in the bathroom.

There are 3 switches on the wall - one vertical, the other 2
horizontal.

The vertical switch is wired to control the light in the heat/vent
unit as well as the 2 other recessed lights via 14/2wg romex. (The
lights are on the load side of the GFCI outlet since one recessed
fixture is above the shower stall.)

The horizontal switches control the heat or vent via 14/3wg.

The top horizontal switch controls the vent, because the vent pulls
air up, the lower horizontal switch controls the heat because the heat
blows down.

Anal? Did I hear someone say anal?

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 22, 3:35*pm, DerbyDad03 wrote:
On Apr 22, 2:43*pm, N8N wrote:





On Apr 22, 1:12*pm, wrote:

I'm in the process of replacing an existing Vent/Heat/Light unit in my
bathroom. *The old wiring setup on this system seems odd to me.

The previous installer is running three Romex wires to the unit.
There is a two gang switch controlling (with one double switch).
* * * * One wire holds the Neutral and ground (other wire is clipped), coming
from source junction box.
* * * * Another wire is holding two feeds from the switch (the ground is
clipped).
* * * * The last wire is holding one feed from the switch (the other wires
are clipped).

Here is my question:
* * * * Due to new location of the new unit, and existing cable size, I need
to extend the two feed Romex cables coming from the switch. *Hence, I
need a junction box to extend the lines. *The issue is, if I use a
metal box then shouldn’t those wires be grounded to the box?
Normally, I would say yes ground the wires to the box. *However, the
previous installer cut the grounds on those cables… so what value
would there be in grounding them? *Another solution is to use a
plastic junction box (which is legal in my town), to avoid the
grounding issue.

Any thoughts?

Thanks,
Raj

The whole thing is incorrect, you should be running one cable from the
switch box to the unit. *Since that is not possible given that you
have three different functions in the unit (unless someone makes a
12/4wg cable?) that is, vent, heat, and light, do any of these
functions have their own neutral? *If that is the case then you should
run a separate cable for the light, say, as a 12/2 w/ground, and then
another cable 12/3 w/ground for the vent and heat. *Neutrals should be
connected to each other at the switch box but NOT in the v/h/l unit.
this way the currents in each cable will sum to zero in the absence of
a ground fault. *All grounds should be connected together and to the
box at all locations.

You will have to run new wire from the switch box to the new location
to be code compliant.

good luck

nate- Hide quoted text -

- Show quoted text -

What N8N describes is essentially what I did, except that there are 2
additional lights in the bathroom.

There are 3 switches on the wall - one vertical, the other 2
horizontal.

The vertical switch is wired to control the light in the heat/vent
unit as well as the 2 other recessed lights via 14/2wg romex. (The
lights are on the load side of the GFCI outlet since one recessed
fixture is above the shower stall.)

The horizontal switches control the heat or vent via 14/3wg.

The top horizontal switch controls the vent, because the vent pulls
air up, the lower horizontal switch controls the heat because the heat
blows down.

Anal? Did I hear someone say anal?- Hide quoted text -

- Show quoted text -

I mentioned 12/2 and 12/3 because I was assuming a dedicated 20A
circuit for the bathroom.

yes, I'm still planning exactly how I'm going to rewire mine.

nate

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 22, 3:41*pm, N8N wrote:
On Apr 22, 3:35*pm, DerbyDad03 wrote:





On Apr 22, 2:43*pm, N8N wrote:

On Apr 22, 1:12*pm, wrote:

I'm in the process of replacing an existing Vent/Heat/Light unit in my
bathroom. *The old wiring setup on this system seems odd to me.

The previous installer is running three Romex wires to the unit.
There is a two gang switch controlling (with one double switch).
* * * * One wire holds the Neutral and ground (other wire is clipped), coming
from source junction box.
* * * * Another wire is holding two feeds from the switch (the ground is
clipped).
* * * * The last wire is holding one feed from the switch (the other wires
are clipped).

Here is my question:
* * * * Due to new location of the new unit, and existing cable size, I need
to extend the two feed Romex cables coming from the switch. *Hence, I
need a junction box to extend the lines. *The issue is, if I use a
metal box then shouldn’t those wires be grounded to the box?
Normally, I would say yes ground the wires to the box. *However, the
previous installer cut the grounds on those cables… so what value
would there be in grounding them? *Another solution is to use a
plastic junction box (which is legal in my town), to avoid the
grounding issue.

Any thoughts?

Thanks,
Raj

The whole thing is incorrect, you should be running one cable from the
switch box to the unit. *Since that is not possible given that you
have three different functions in the unit (unless someone makes a
12/4wg cable?) that is, vent, heat, and light, do any of these
functions have their own neutral? *If that is the case then you should
run a separate cable for the light, say, as a 12/2 w/ground, and then
another cable 12/3 w/ground for the vent and heat. *Neutrals should be
connected to each other at the switch box but NOT in the v/h/l unit.
this way the currents in each cable will sum to zero in the absence of
a ground fault. *All grounds should be connected together and to the
box at all locations.

You will have to run new wire from the switch box to the new location
to be code compliant.

good luck

nate- Hide quoted text -

- Show quoted text -

What N8N describes is essentially what I did, except that there are 2
additional lights in the bathroom.

There are 3 switches on the wall - one vertical, the other 2
horizontal.

The vertical switch is wired to control the light in the heat/vent
unit as well as the 2 other recessed lights via 14/2wg romex. (The
lights are on the load side of the GFCI outlet since one recessed
fixture is above the shower stall.)

The horizontal switches control the heat or vent via 14/3wg.

The top horizontal switch controls the vent, because the vent pulls
air up, the lower horizontal switch controls the heat because the heat
blows down.

Anal? Did I hear someone say anal?- Hide quoted text -

- Show quoted text -

I mentioned 12/2 and 12/3 because I was assuming a dedicated 20A
circuit for the bathroom.

yes, I'm still planning exactly how I'm going to rewire mine.

nate- Hide quoted text -

- Show quoted text -

Ya know...it's been so long and I'm not home now, but it very possible
that everything I said about 14/2 and 14/3 should be 12/2 and 12/3.
Either that or I ganged two 15A breakers and ran 2 circuits. I
remember how I wired it, now you've got me wondering what I wired it
with!

Da*m, now I gotta go home and check.

Rewiring a Vent/Heat/Light unit in bathroom
 

"DerbyDad03" wrote in message
...
On Apr 22, 1:12 pm, wrote:
I'm in the process of replacing an existing Vent/Heat/Light unit in my
bathroom. The old wiring setup on this system seems odd to me.

The previous installer is running three Romex wires to the unit.
There is a two gang switch controlling (with one double switch).
One wire holds the Neutral and ground (other wire is clipped), coming
from source junction box.
Another wire is holding two feeds from the switch (the ground is
clipped).
The last wire is holding one feed from the switch (the other wires
are clipped).

Here is my question:
Due to new location of the new unit, and existing cable size, I need
to extend the two feed Romex cables coming from the switch. Hence, I
need a junction box to extend the lines. The issue is, if I use a
metal box then shouldn’t those wires be grounded to the box?
Normally, I would say yes ground the wires to the box. However, the
previous installer cut the grounds on those cables… so what value
would there be in grounding them? Another solution is to use a
plastic junction box (which is legal in my town), to avoid the
grounding issue.

Any thoughts?

Thanks,
Raj

"The old wiring setup on this system seems odd to me."

Is it possible to eliminate the existing (and bizarre) wiring and do
it correctly?

I would seem to me that this is the perfect time to correct a bad
wiring installation instead of simply extending it.

WWALED? (What would a licensed electrician do?)

This electrician would run a 12/4 Romex, and if the unit had four functions,
light-heat-fan- night light, I would run 1/2 inch greenfield with a ground,
neutral, and four hots

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 22, 5:32*pm, "RBM" wrote:
This electrician would run a 12/4 Romex, and if the unit had four functions,
light-heat-fan- night light, I would run 1/2 inch greenfield with a ground,
neutral, and four hots- Hide quoted text -


Sorry for the ignorance... here are some questions:
1) "1/2 inch greenfield" is a type of conduit?
2) This unit does have four functions, for the "ground and neutral",
would you use a 12/2 and clip the other wire? Would this also mean
the 12/4 would have its ground clipped?

Raj

Rewiring a Vent/Heat/Light unit in bathroom
 

wrote:
On Apr 22, 5:32 pm, "RBM" wrote:

This electrician would run a 12/4 Romex, and if the unit had four functions,
light-heat-fan- night light, I would run 1/2 inch greenfield with a ground,
neutral, and four hots

Sorry for the ignorance... here are some questions:
1) "1/2 inch greenfield" is a type of conduit?

yes. think BX without the wires in it. You pull individual conductors
of THHN through it.

2) This unit does have four functions, for the "ground and neutral",

No it doesn't, he's talking about how many hots you need. you have
three functions, plus you need a neutral and ground.

would you use a 12/2 and clip the other wire? Would this also mean
the 12/4 would have its ground clipped?

No. read my earlier post - you need to get rid of all that's existing
and pull new cable. I guess RBM has actually seen 12/4, I haven't but I
haven't looked nor had a need for it. The whole point is, you need your
currents to sum to zero within every single cable assembly, and that's
not currently happening with what you have. The reason for this is to
minimize inductive heating of the wires.

Like I said before, if you have one of the functions where you can
isolate the neutral you can pull one 12/2 and one 12/3 and make it work.
If you can't, you need to either pull a 12/4 if such is available or
else go with greenfield, EMT or something like that - which will likely
involve painting and patching at some point.

good luck

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Rewiring a Vent/Heat/Light unit in bathroom
 

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

Rewiring a Vent/Heat/Light unit in bathroom
 

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

Rewiring a Vent/Heat/Light unit in bathroom
 

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

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 23, 9:07*am, N8N wrote:

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.

But Nate, there's only one source feed to the unit anyway... so
wouldn't it still sum to zero?

Currently, the switch box is geting power from one junction box, and I
need to split that line (in the switch box) into the four feeds of the
four switches.

Thanks again for all you help,
Raj

Rewiring a Vent/Heat/Light unit in bathroom
 

On Apr 23, 2:31*pm, wrote:
On Apr 23, 9:07*am, N8N wrote:



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.

But Nate, there's only one source feed to the unit anyway... so
wouldn't it still sum to zero?

yes, over *all* the cables. but if you have, say, only the light
turned on and its feed is in one cable and the neutral is in another,
the individual cables no longer sum to zero.

nate


Currently, the switch box is geting power from one junction box, and I
need to split that line (in the switch box) into the four feeds of the
four switches.

Thanks again for all you help,
Raj

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

Rewiring a Vent/Heat/Light unit in bathroom
 

RBM wrote:
"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



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

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