KingsX Posts: 231, Reputation: 10 Full Member #1 Oct 4, 2009, 09:15 AM
Multiple baseboards with multiple thermostats one circuit
Hi again guys, I want to run multiple baseboard heaters one one circuit in my basement. I have a small basement, so I figure I will need about 4 total baseboards. I figure I'll need about 4000 watts, I'm running 240 volt. So according to my code where I live, I'll require #12 and a 30 amp breaker (code states #12 and 30 amp with 240, I can go up to 4800 watts).

So am I correct in saying that I would wire this like a multiple light fixture/switch arrangement? Meaning, I would bring in the #12 to the first thermostat, using a pigtail I would connect that to the thermostat and then to heater #1. In that same first thermostat, I would continue wire to thermostat #2, and so on. Is this the correct way to do it? This seams to me to be the only way. The only other thing to do would be to put each baseboard heater on its own breaker, which then I could use #14 and a 15 amp breaker, but I'd rather not do it that way. Let me know, thanks again guys!
 mygirlsdad77 Posts: 5,713, Reputation: 339 Plumbing Expert #2 Oct 4, 2009, 12:17 PM

As far as I know, each basboard requires its own thermostat, and dedicated breaker. 15 amp breaker is not nearly enough for 240 baseboard. Hope one of the electricians can pop in here.
 KISS Posts: 12,510, Reputation: 839 Uber Member #3 Oct 4, 2009, 12:40 PM

Whoops:

4000/240= 16.66A

Must be multiplied by 1.25 because heating is a continuous load

thus 20.83 amps

Upsize breaker to next size 30 A

Can't use #12, Use #10 wire

I'm missing something.

Multiple thermostats is OK, but why?

Sometimes it's hard to find a line stat for currents over about 22 Amps. You can use a relay to boost that. There are digital line stats.

What I have done for mechanical stats is wire a standard toggle switch in series with a mechanical thermostat. That way the setpoint stayed constant and you had an easy way of knowing whether the heat was on. You'd need a special switch to do it in your case.

You can also use a contactor and brig everything into that box, providing you can put it in an accessible location.

These guys have an interesting selection of line voltage stats.

Products | Fastenal

The contactor may be the way to go. If need be you can put a an access panel somewhere and a large junction box under it.

You can also then use a 24 VAC stat too and make your options easier. Like programmable etc.
 medic-dan Posts: 321, Reputation: 23 Full Member #4 Oct 4, 2009, 03:35 PM

Standard practice for my area is that there is a dedicated circuit run to each thermostat. You can have more than one heater per thermostat.
 KingsX Posts: 231, Reputation: 10 Full Member #5 Oct 4, 2009, 10:20 PM

Kiss, I'm a little confused by your answer, you'll have to excuse me nooby-ness. But anyway, my electrical installations code book for my city says "maximum connected heating load, not more than 4800 watts, requires #12 with a 30 amp breaker".

Just for your own FYI, here is a link to my city's code in PDF, check pages 27 and 28 for this specific topic, but you might be interested in code for a Canadian city anyway...
http://www.winnipeg.ca/PPD/pdf_files/HOElec.pdf

But anyway, you're always a wicked help kiss, but I'm having trouble understanding what you mean? Are you saying that normal thermostats can't handle that much current? Again sorry for my nooby-ness :)
 KISS Posts: 12,510, Reputation: 839 Uber Member #6 Oct 4, 2009, 11:45 PM

OK, I upped it because our code the NEC requires circuits to be oversized by 1.25 when on for more than 3 hours at a time. Heating loads must be sized at 125&#37;. So, I just made the wire gage a little bigger because of the 0.83 amps.

This is a line voltage stat. Product Details | LineVoltPRO 8000 220V Digital Programmable Line Volt Stat | Fastenal which is rated for 15 amps. They have no product that can handle 15 amps at any voltage.

Are you saying that normal thermostats can't handle that much current?
Yes.

Here is a stat rated for 22 amps. Honeywell T498B1512 Electric Heat Line Voltage Thermostat

And that's probably about as high as it gets.

These stats are stupid and you have to keep turning it to a difficult to read setpoint Every time you turn it on. It' then becomes too hot or too cold, that's why I used a switch in series with the stat.

So, you need to figure out what you want.
1. 1 stat vs multiple stats
2. Easy set point manipulation
3. Programmable?
4. Line voltage vs. 24 volt
5. some of the line voltage stats require a minimum load like 2 Amps to work.
6. Temp Sensor somewhere other than the location of the stat.
(e.g. sensor near where you sit and tstat near entrance to room)

The biggest problem is the stat handleing the amount of current directly.

A relay(called a contactor in this sense) and a 24 VAC transformer essentually turn the system that can use thermostats designed for funaces that use electric heat.

Now, you have more options to choose from for thermostats.
 KingsX Posts: 231, Reputation: 10 Full Member #7 Oct 5, 2009, 06:33 AM

Okay, I see what your driving at. And in regards to the wire gauge, I'm not afraid to go higher than required either, as its safer regardless.

Anyway, well the baseboard heaters I'm looking at are these...
Dimplex - 750W/240V Baseboard Heater - White - DBH-0750W - Home Depot Canada

And they offer this as a thermostat option...
Dimplex - Wall-Mount Double Pole Thermostat Kit - TD322W - Home Depot Canada

I suppose I should pick one up and consult the manual. But do these thermostats make sense?
 KISS Posts: 12,510, Reputation: 839 Uber Member #8 Oct 5, 2009, 07:04 AM

There may be a typo in the model. The Dimplex site places these at 22A. Dimplex Technical Support Files

Incidentally, both tstats on the page point to the same manual.

Essentially these stats use a bi-metalic switch. They are not too accurate and every time you use them you have to move the setpoint.

By putting something like this: Switch,Manual,2 Pole - Manual Motor Switches and Starters - Starters and Contactors - Electrical : Grainger Industrial Supply

In series with the stat, you avoid the messing with the setpoint problem. Note that this is a toggle switch rated for 30 A.
 KingsX Posts: 231, Reputation: 10 Full Member #9 Oct 5, 2009, 08:04 AM

Okay, I see what your saying. But in regards to wiring this up, because I have to have a thermostat in each room, was my original assumption correct? I would go #10 from panel to tstat one, pigtail to the tstat, while wire nutting the next run to tstat #2 and so on?
 KISS Posts: 12,510, Reputation: 839 Uber Member #10 Oct 5, 2009, 08:25 AM

I re-read your post and there was nothing about tstats in each room. I also U MEed that there were four heaters in one big room. OOPS.

You will basically will likely run in to bcx fill requirements if you try to say take the 30 amp feed to one stat and pigtail to 3 other stats and also have a tsat in the same box. Just won't likely work.

I see some options:

1. Use a small sub-panel and then separate circuits for each heater. Smaller wire size then can be used.

2. Use circuits in breaker panel. If running out, use twin breakers. Two circuits in a single space. Available in 15/15, 15/20 and 20/20 varieties. Use these for other circuits, not the heating ones. Watch out for the # of pole limit listed on the box.

3. Run each of the wires into the breaker box to each thermostat and pigtail there so that only 1 wire is attached to each of the 30 amp breaker terminals.

4. Use a separate junction box where power disttributes to the 4 thermostats.

Your code did not mention wheter or not GFCI's or AFCI's are required. At least I didn't see it.

If you go with separate circuits and you want to use the switch, then standard switches will do.
 KingsX Posts: 231, Reputation: 10 Full Member #11 Oct 5, 2009, 09:48 AM

You're right, I didn't mention the multiple thermostats. I did in the title, but I should have mentioned it again. My mistake. I like option 4 actually. I was originally thinking of running three sets of #10 (or #12 if I'm under 4800 watts) into each thermostat box. One would be from the breaker, the second would be the feed to the next thermostat and the third would be from the heater. This way in the second tsat box, it would be three again because it would be from the first tstat, the wire to the third tsat and from the second heater. But you think I wouldn't be able to run three sets of #12 or #10 into a standard electrical box for the tstats?

EDIT: The last tsat would only have two sets of #12, because it would be from the previous tstat and then the heater etc.
 KISS Posts: 12,510, Reputation: 839 Uber Member #12 Oct 5, 2009, 10:59 AM

See what happens under the NEC:

More Wires Need Bigger Boxes - Fine Homebuilding Article

Box Fill Calculations

Have existing flushed 2"x3"x2-1/2" metal box with (2) clamps.
(empty abandoned box @12.5cu in.)

Say 3 cables of #10 or 6 wires

1 unit for ground
2 for the switch
1 for the clamps
3 cables or 6 wires not including ground (power in, power out and power to heater)

Let's say it was #12 wire:

That's 7 * 2.5 > 12.5

So if #12's won't fit, neither will #10's.

PS: You may also need a deep box for the thermostat.
 KingsX Posts: 231, Reputation: 10 Full Member #13 Oct 5, 2009, 11:25 AM

Ya, okay I see what your saying. So no matter what I do, I think that your option #4 is best for me. If I run #12 for instance, and I need 4 heaters with 4 thermostats, I can run from the breaker into a junction box. From there, wire nut my four sources for the tstats and then from each of those boxes, run to the heaters.

But do they even make a junction box big enough for 5 sets of #12? Or even if I have to go #10? Even in the thermostat boxes, a "device" according to my code book (for instance a switch, receptacle, or thermostat) counts as 2, so whatever my max is, I have to subtract 2. Or could you run a couple or three junction boxes next to each other? Or is that getting ridiculous already?

Maybe I should just have a separate circuit for each heater? Then I can use #14, and not worry about it. Or depending on how much my wattage is added up, I might be able to do two heaters on #14. For instance a 1500 watt, and a 750 watt.
 KISS Posts: 12,510, Reputation: 839 Uber Member #14 Oct 5, 2009, 11:35 AM

They make huge junction boxes, however if you need a nice looking one, you could go say maybe 3 gang with a blank pretty plate.

Remember the cable clamp and the ground wire.
 KingsX Posts: 231, Reputation: 10 Full Member #15 Oct 5, 2009, 11:40 AM

Okay, I'll take a look at that option. I might run half the basement on one circuit and the other half on another etc. But I'll give it some thought. As always Kiss, you're a big help!
 KISS Posts: 12,510, Reputation: 839 Uber Member #16 Oct 5, 2009, 12:05 PM

Your welcome and thanks for the intro to Canadian code.

There is always a balance:
You have to do it legally and cost effectively where labor costs and time can enter into the equation. You con do things with upgradability in mind, too.

Sometimes I like to use the following:

If I had all the money in the world how would I do it.
Then ask what do I need?
What might I want later?

For example, I painted a room at home. I installed a dual gang low-voltage box with connecters even and drilled the hole and inserted a fish string. They just aren't connected to anything.

It was the perfect time to install the box. Later as time permits or things are needed. I can install phone, Ethernet or TV.

Actually there was an old twin lead system in that room from 40 years ago.

Telephone and Ethernet need to be re-done from the ground up. Everything is stable even with non-home runs and quad cable and lots of telephones.
Porch (modular and 4 prong outlets available)
Kitchen - wireless and wired phone on wall
Living room - wireless #1 from base
Mom's room: Ans mach/base + PERS alarm system; Base + wireless handset #2
My room - standard phone + wireless handset #3
Laundry - Bell only; DSL modem
Den - phone - ringer disconneted
Basement kit - wireless handset #4; wireless router to phone line - Legacy, Bell
My shop - modem

So there's a mess to clean up.
 KingsX Posts: 231, Reputation: 10 Full Member #17 Oct 5, 2009, 12:22 PM

Yikes, lots to do! I've got this tiny little house, with knob and tube. And my wife and I want to sell it in the spring, so we're working on upgrades right now. I have a new service and panel coming in this week. Then I'm going to start rewiring the house. I currently work as an installer for pro audio and lighting, meaning PA systems and stage lighting for halls, and clubs etc. So I have some experience with this stuff. This is why I want to install baseboards in the basement. I only have main floor boiler radiant heat, and no heat in the basement. Which makes for cold hard woods! But I have to run new wire into the attic (not looking forward to that) to supply new service to my fixtures and switches. Thankfully everything is accessible in the basement as it isn't finished yet. So main floor stuff won't be as difficult.

I would love to rip the plaster and lathe down and start all over, but I have two small children and no where else to stay while I spread who knows what, asbestos or lead paint dust into the air. So retro fit will have to do.

Which brings up another question. I have a whole 7 light fixtures on the main floor. Could I not bring one #14 into the attic, into a junction box (just like the heaters) and feed all fixtures and switches from there? Or at the very least, two #14's? At first I was thinking of putting each fixture on its own circuit, but the daunting task of running 7 #14's through the wall into the attic and then taking up all that space with breakers in my new panel just seems like lunacy to me? What do you think?
 KISS Posts: 12,510, Reputation: 839 Uber Member #18 Oct 5, 2009, 12:48 PM

Sure. Fixtures are probably limited to 60 W and even with ceiling fans in all the fixtures, that's 1200/7 Watts per fixture.

It's best to keep lighting on separate circuits than the recept. Anyway. Two circuits would make things safer. Meaning, if one circuit failed, there would be a room on the same floor with lights.

JUnction boxes must be accessible, meaning not hidden and covered up by a wall.

I'd run 14/3 for the switch loops. Many devices such as timers are requiring neutrals these days. It might also help those wanting to install ceiling fans with a light and fan swiches. The extra cost might be worth it.

In the bath you could consider a totally separate supply for the ceiling fixture (e.g. light/heater/fan). Again, it might be worth it. Wire for it with blank cover plates and/or run a conduit.

Generally, your not supposed to leave unused circuits hanging in the walls. See what the inspector has to say.
 KingsX Posts: 231, Reputation: 10 Full Member #19 Oct 5, 2009, 01:08 PM

That's awesome, those are great ideas. I was thinking maybe two like you mentioned, and a third dedicated for a smoke detector. That'll save me so much time not to have to run 7 wires! Thanks!
 KISS Posts: 12,510, Reputation: 839 Uber Member #20 Oct 5, 2009, 02:04 PM

Remember too, you don't have to wire with Romex. PVC and flexible conduit are options even if it's just used to get wires into the attic using THNN wire.

Electrical Conduit Basics

There are fill requirements for conduits as well.

This tool might be able to help you: BR250 - Video Borescope/Wireless Inspection Camera

It only \$300 USD

Dewalt makes a nice drill, but it's expensive too, again around \$300 USD which has an interesting feature. It won't grab things and rip out your arm. It has a built in torque limiter.

This one: http://www.dewalt.com/us/products/to...roductID=20509

The DWD460K; DeWalt DWD460K 1/2-Inch Right Angle Stud & Joist Drill Kit w/ Bind-Up Control - \$319.99 - ToolKing.com

The big bits with big holes require big drills. You are aware of the long length drills (home Depot has them the steering wheel that can drill sideways etc.

Such as these:

Greenlee Products - Greenlee A Textron Company

The page doesn't do it justice. There is guide gizmo that's used with it as well. Note these bits are flexible and 54" long and you can add an extension
Too.

Here is a better page: Piranhabits Drill Bits are Flexible Shaft Fish Bits available from Lashen Electronics

What I do is cut out the outlet opening at fit it with a metal low voltage ring which justs bends into place. This will provide a metal edge so the edges of the wall won't get damaged. I don't like these: Low Voltage Device "Box Eliminator" Ring - One Gang, but the electrical supply house has the ones I like to use. Instead of using screws a portion of the center section just bends around the wall.

Here are the ones I like:
http://www.projectorzone.com/Cables-to-Go-03784
Took me forever to find an online seller.

Your going to need all the help you can get!

EDIT: Stud and Joist drill model #
EDIT #1: low voltage mounting brackets updated p/n

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