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When you open that link for the thermostat look at the left of the screen and read line 5Originally Posted by diydude
Edited to add;
Also look at the bottom of the first page at line 4
Yes, those were the two bullets I noticed when I looked through the manual. I just reread it, and I've got it now. I've decided to stick with my plan to install the two 20-amp circuits:
- Circuit #1: Two GFCIs
- Circuit #2: Floor heat, downstairs bathroom fan and lights
Last edited by diydude; 08-02-2012 at 09:23 PM.
Ok, I have a couple requests for confirmation. I'm running my wiring through the crawlspace. I was reading through Chapter 296-46(B) WAC as is referenced by my city's electrical code (fun reading - NOT!)
Link to Chapter 296-46(B) WAC: http://apps.leg.wa.gov/wac/default.a...ue#296-46B-334
(1) The "015 Exposed work" section mentions that the NEC protection standards for NM cable in crawlspaces do not apply in Washington; no need to bore holes in floor joists or use running boards when running cable perpendicular to floor joists. I just wanted to confirm and make sure I didn't miss something.
(2) The other thing I read in section "015 Exposed work" was about a 2 1/2" requirement for cable protection. It appeared to not apply to installations being covered by drywall. The NEC 1 1/4" requirement would apply instead for drywall. Please confirm.
Thanks!
Last edited by diydude; 08-04-2012 at 08:06 AM.
I think that the link you posted calls for a circuit no larger than 15 amps and for it to be all by itself if possible.
Being that you are installing this new then it is possible for it to be on a deciated circuit
Yeah, the instructions seem ambiguous. The mat instructions mention the following:
Maximum Circuit Overload Protection 20 A Breaker
Maximum Circuit Load 15 Amps
One other thing I saw, which led me to think that they were providing general NEC-type guidelines for residential circuit wiring, is step 1.2 of the mat instructions. Also, see page 19, which mentions a typical 20A circuit for one mat: http://www.warmwire.com/media/SunTou...urrent-WYF.pdf
Also, why would you have a cap on the breaker size if everything is being wired in parallel?
Last edited by diydude; 08-04-2012 at 12:10 PM.
The maximum circuit that can supply the mat regardless of the square feet being covered is 20 amp. The largest load the circuit of the mat can carry is 15 amps. All this is directed to the mat itself and has nothing to do with the controller that you posted.
Should one to decide to use a larger mat then they would choose a larger controller that would match the square footage being installed.
http://www.warmwire.com/products/con...hermostat.html
The controller which is the weakest link in this circuit is what will mandate what is to be installed. It requires a 15 amp circuit and recommends a dictated circuit.
As an electrical inspector I would not pass the installation should it not be as the controller states in its installation instructions.
As to your cable installations question, I can’t address Washington but the here in NC we are not requiring anything special in the crawl space or any hole drilling.
Each node of a parallel circuit will add current to the entire circuit. In the node for the heating mat the mat and its controller will be a series circuit of a predetermined resistance. This node will add to the other nodes of the circuits for a total amperage draw that the conductor must be capable of carrying.
The total resistance of a parallel circuit will always be less than the lowest resistance of any single node. Should one of those nodes lose all resistance then the amperage draw will increase to the point that damage would occur to the insulation on the conductor. This is the job of the fuse or the circuit breaker. It will open in the event of a high current draw and protect the conductor.
A GFCI device does not open in the event of an overcurrent event. All the GFCI device is looking for is a difference between two current carrying conductors of 4 to 6 milliamps.
What the manufacturer of the GFCI device is saying is if more than 15 amps is allowed to flow through this device it could damage the integral wiring of the circuit board and render the device useless.
Ugh, ok. jwelectric, I'll take your suggestion. Please confirm this is what you stated:
Circuit 1 (20 amps): GFCIs only
Circuit 2 (15 amps): Floor thermostat and mat
Circuit 3 (Existing 15-amp branch circuit): Add recessed light and sconces that are substituting for existing vanity lights
Edit: My concern is overloading the 15-amp branch circuit. When I add up the wattage, including the new recessed light, I'm at 1575W. This would most likely not pass an inspection, correct?:
Lights fixtures:
- kitchen (2): 240W (4 - 60W bulbs)
- chandelier (1): 360W (6 - 60W bulbs)
- downstairs bathroom (1): 315W (Recessed light (75W), Sconces (4 - 60W bulbs))
- deck (1): 180W (2 - 90W bulbs)
- downstairs bedroom (2): 120W (2 - 60W bulbs)
Outlets:
- downstairs bathroom GFCI (1)
- downstairs bedroom (1)
- upstairs bathroom GFCI (1) - probably not necessary that it be GFCI, since it feeds off the downstairs GFCI. Anyway.
- living room (1)
Other:
- downstairs bathroom fan (180W?)
- kitchen range hood (180W?)
Last edited by diydude; 08-04-2012 at 11:46 PM.
Are you planning on having all these light on at the same time?
If it is a concern while the walls are open then install an addtional circuit
No, I wouldn't have all the lights on at the same time; there are only two of us in the houseI remember reading something about a 3-hour continuous load, and only the deck light would be on continuously for 3+ hours. I believe I have 5 open slots in the panel (although, it's only a 60-amp panel - that's another issue I'll have to deal with later), so I could run three new circuits.
I'd have to amend my electrical permit. Oh, boy. And yes, I was supposed to meet with an electrician this past Thursday before applying for a permit, but they never showed. So, I decided to move forward with getting permits before the weekend.
Last edited by diydude; 08-05-2012 at 09:18 AM.
There is a difference between calculating a load for commercial and industrial than doing a dwelling unit calculation.
In industrial and commercial we do a continuous calculation but for a dwelling we do the 3 watts per square foot and no continuous load for these circuits.
Although it is a good idea to do the wattage per light fixture for branch circuits there is no need to do the continuous factor to the circuit. It is very unlikely that one would have 1400 watts of lights burning for a very long period of time let alone for three hours at a time. Should someone do this repeatedly the power company would invite them to the board of directors meeting as a stock holder.
LOL. Ok, thanks. So, I'll just add the recessed light to the existing 15-amp circuit and call it good. Thanks for the advice.
Ok, I have another question. I'm investigating another floor warming system by Warming Systems, Inc. The instructions mention that only a certified electrician can connect the floor heating mat (I'm actually going to be using the warming wire instead of the mat - don't think it matters). Do I need to worry about this mandate with regard to an inspection?
http://www.warmingsystems.com/Cable%...structions.pdf
Only a certified electrician who is familiar
with electrical installation codes and
practices can connect the floor heating mat.
All wiring must comply with the
specifications in the US National Electric
Code and all local electrical regulations
and standards.
Last edited by diydude; 08-07-2012 at 10:16 PM.
You may lose any warranty claim if not installed by a licensed electrician.
Jim DeBruycker
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013
I can live with that. I'm just concerned about legal issues.
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