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Old 01-09-2010, 07:43 PM   #1
Join Date: Jan 2010
Location: Philly
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Wire question


I am wiring a bathroom. All new construction.

I am planning on running 12/2 wire from a 20amp circuit in my electrical box to my first switch box. The switch box is going to control a canister light over the tub/shower, the ceiling light, and the ceiling fan (combined unit with the ceiling light). Each of these will be on separate switches.

First, question: when I run cable from these switches to their respective light or fan, do I also need to run 12 gauge wire? Or can I run 14 gauge wire even though I am using 20amp circuit and 12/2 wire to get power to the first switch box?

From the first switch box, I am planning on tying that to another switch box. In the second switch box, I will have two switches. One for two sconces on the sides of the bathroom mirror and another switch for the under-tile heated floor element.

Second, question: Can I do that? Can I run one line from the electrical box to a switch box and then from that switch box to another switch box?

I wouldn't mind putting all five switches in the same box. However, it seems like a lot and I am not sure I have enough room on the wall (small bathroom) especially when I want to have dimmer switches for the ceiling light and the sconces.

I would greatly appreciate any comments on this plan.

Thanks in advance!


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Old 01-09-2010, 08:00 PM   #2
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Join Date: Dec 2009
Location: NC
Posts: 369

Wire question

Article 210.11(C)(3)

(3) Bathroom Branch Circuits.
In addition to the number

of branch circuits required by other parts of this section, at
least one 20-ampere branch circuit shall be provided to
supply bathroom receptacle outlet(s). Such circuits shall have no other outlets.

Exception: Where the 20-ampere circuit supplies a single
bathroom, outlets for other equipment within the same
bathroom shall be permitted to be supplied in accordance

with 210.23(A)(1) and (A)(2).

210.23 Permissible Loads.

In no case shall the load exceed

the branch-circuit ampere rating. An individual branch
circuit shall be permitted to supply any load for which it is
rated. A branch circuit supplying two or more outlets or
receptacles shall supply only the loads specified according
to its size as specified in 210.23(A) through

(D) and as
summarized in 210.24 and Table 210.24.

(A) 15- and 20-Ampere Branch Circuits. A

15- or 20ampere

branch circuit shall be permitted to supply lighting
units or other utilization equipment, or a combination of

both, and shall comply with 210.23(A)(l) and (A)(2).

Exception: The small-appliance branch circuits, laundry
branch circuits, and bathroom branch circuits required in a
dwelling unites) by 210. 11 (C)(l), (C)(2), and (C)(3) shall

supply only the receptacle outlets specified in that section.

(1) Cord-and-Plug-Ormnected Equipment Not Fastened!
in Place.

The rating of anyone cord-and-plug-connected

utilization equipment not fastened in place shall not exceed

80 percent of the branch-circuit ampere rating.

(2) Utilization Equipment Fastened inPlace. The total

rating of utilization equipment fastened in place, other than
luminaires, shall not exceed 50 percent of the branchcircuit
ampere rating where lighting units, cord-and-plugconnected
utilization equipment not fastened in place, or

both, are also supplied.

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Old 01-09-2010, 08:12 PM   #3
Join Date: Jan 2009
Location: South of Boston, MA
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Wire question

You can't use 14g wire on a 20a circuit
5 switches.....that's a lot...I only have 3, 4th is a programmable thermostat for radiant heat
They do have dual & triple switches
I use the duals here & there
I only have one triple I think


What kind of switch are you using for under the floor ?
If electric that requires a GFCI protected circuit & usually a thermostat is installed

I have one switch outside the bathroom - overhead light
A dual switch on thebathroom controls vanity light & fan
The thermostat is on a different wall all by itself
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Old 01-10-2010, 03:40 AM   #4
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Location: Baltimore, MD
Posts: 332

Wire question

The floor heat will need a separate 20 amp circuit - at least every one I have done required it per manufacturers instructions.
Also, I would place the receptacles on their own 20 amp circuit. You are required to do this, but would be permitted to place the lights on that circuit as well. (See Codeone's post) I would just run another 15 amp circuit for the lights.
John from Baltimore
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Old 01-10-2010, 06:22 AM   #5
Just call me Andrew
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Location: Albany, NY
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Wire question

They also make decora-style double and triple switches. A little more pleasing to the eyes in my opinion:

Also, if you were planning to use a normal switch for your radiant floor instead of a thermostat, I am thinking you could use a timer like this to control it:


Last edited by secutanudu; 01-10-2010 at 06:27 AM.
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Old 01-10-2010, 05:02 PM   #6
Join Date: Jan 2010
Location: Philly
Posts: 29

Wire question

Thanks to all of you who replied.

Based on your comments, I have revised my plan. Please let me know if this one is better.

On one wall, two swtiches. 1. On/off switch for Ceiling fan. 2. Dimmer switch for Ceiling light. I like those decora-style double and triple switches. But, I thought it would be nice to have a dimmer on the ceiling light and I haven't seen a double switch that has a dimmer as one of the switches.

This ceiling light/fan is one unit. It only draws 2.2 amps. So, 15amp circuit for it alone. Overkill?

On another wall, two switches and a thermostat. 1. Dimmer switch for the mirror sconces. 2. On/off switch for canister light above the bath/shower. 3. Thermostat for the heated floor.

I double checked the instructions on the heated floor unit. The unit only draws 2 amps. It recommends a separate circuit, but that seems to be for a larger unit than I have. So, I was going to do a 15amp GFCI circuit for all three of the switches (sconces, canister light, and thermostat) on this wall. The (SunTouch) thermostat instructions say to supply it only with 15amp. So, I was going to do one 15 amp circuit for all three of these. Is that enough? I haven't bought the canister or the sconces yet, but I can't imagine them drawing too much amperage.

Aside from all of these, I was going to put two or three receptacles on separate 20amp circuit. If I do two or three circuits, can I put them both on one 20 amp circuit?

In summary, I would have three power leads to my bathroom. One for the ceiling light/fan (15amp), one for the heated floor, sconces, and canister light (GFCI 15amp), and one for the receptacles (20amp).

Does this new plan work?

I appreciate your time and expertise!

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Old 01-10-2010, 05:23 PM   #7
Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248

Wire question

My lights & ceiling fan are all connected to a general lighting circuit
This is allowed by code
A 15a circuit for 2.2a is overkill
But if you are going to be adding other lights in the house you could run them on this circuit

My radiant heat took 6a - I installed it on a 15a circuit that is shared wityh another device
Together they do not exceed 12a, acceptable
Possible you could combine lighting & radiant floor all on one 20a circuit
This would depend upon total load

My 2nd floor will have 3 outlets on my dedicated 20a run to the bathroom
The number of outlets is not restricted, only that they all have to be in the bathroom
I think you meant 2-3 outlets.......
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Old 01-10-2010, 05:28 PM   #8
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Posts: 29

Wire question

Thanks, Dave. I mean outlets when I say receptacles. I was going to put two to three outlets in the bathroom alone.

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