Electrical question (NOT in house): extension cords and heaters.

O

OilStasher

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Dec 6, 2019
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Somewhere between Nb and Tc
Don't instantly say NO, hear me out!

Hi all, I'm not exactly an amateur with home wiring. I'm knowledgeable enough to be more skilled than the saying "I know how to get myself into trouble." But getting into technicalities is above me. I'm basically just double checking my assumption.

I have a portable radiator style space heater in a detached unfinished garage/shop (completely empty) which is used to prevent my pipes from freezing (it has a toilet and sink inside it). I keep the heater almost at the bare minimum setting and it keeps it plenty warm enough.

I just bought a thermostatically controlled wall tap to use out there (it was $3, why not?), but there is no outlet in the bathroom. The water is shut off out there, so there's no chance of any water/floor/electrical issues unless the pipes burst. The entire garage including the bathroom is a concrete slab.

The problem? The closest outlet is in the main open area of the garage, approximately 2 feet from the bathroom door. The heater is in the bathroom, with the door closed and the cord draped under it (there's a decent gap, zero chance of cord damage). If I plug the tap directly into the wall outlet, it will sense the colder temperature of the main area, not the proper heated bathroom temperature.

So here's my thought process/question. I plan to use an extension cord to make this work. Basically I'm planning to do:

Wall outlet-->extension cord-->thermocube (placed in the bathroom)-->heater

I know the shorter the length of cord the better, but I also know the lower the gauge of cord the better. I have two options for extension cords. I have a 50ft 14-gauge cable, or I have a 100ft 12-gauge cable. I don't buy garbage, both are high quality and new. I'm personally leaning toward the 100ft cable because of the lower gauge. I'm sure either would be fine though.

I also plan to plug in a single 8W LED as an indicator light (which I can see from the main house) to ensure the tap is functioning properly. I trust nothing new...

So long story short, would a quality low-gauge cord with the thermocube on the end, which is hooked to a minimal setting heater be okay to use in a detached, empty, unused, uninhabited garage? What would you do differently? Which of those two cables would you use? Thanks.
 
The wall tap is simply a switch attached to a temperature sensor. I wouldn't hesitate to use it at the end of an extension cord.

As far as the extension cord....depends on how much power is drawn by the space heater plus the thermostatic control.

14ga is rated at 12amps / 1440 watts.

12ga is rated 16amps / 1920 watts.

Saving energy by making sure it won't run constantly makes sense.
 
Originally Posted by JLTD
The wall tap is simply a switch attached to a temperature sensor. I wouldn't hesitate to use it at the end of an extension cord.

As far as the extension cord....depends on how much power is drawn by the space heater plus the thermostatic control.

14ga is rated at 12amps / 1440 watts.

12ga is rated 16amps / 1920 watts.
The heater is "rated" 120V, 60Hz, 12.5 Amps, 5200 BTUs, Three settings: 600/900/1500 Watts. I always use the 600 watt setting, with the 'thermostat' (cold/warm dial) set to almost minimum. I think the 14-gauge would be plenty capable, but I'm leaning toward the 12-gauge out of caution.

Originally Posted by JLTD
Saving energy by making sure it won't run constantly makes sense.
Yes, that's part of it, but honestly it's more of a laziness thing. I'm tired of walking way out there late at night and early in the morning to plug/unplug it.
 
Originally Posted by zrxkawboy
I'd buy a short, "appliance"-type extension cord.
Yeah, that would be a lot less cumbersome than a needlessly long cord.
The height at which you locate the thermostat in the bathroom will affect the temperature it senses. Be sure its current or power rating is above that of the heater.

The indicator light is a good idea, considering the thermostat may fail eventually.
 
Originally Posted by zrxkawboy
I'd buy a short, "appliance"-type extension cord.

Completely fair point, but I don't have one. Before I buy one of those, I'd much rather buy a 'smart outlet' for ~$15 and just control it over wifi. But I also didn't want to pay a $15 lazy tax (see above), so $3 was much easier to swallow. I already owned the extension cords. Thanks for the advice though. I actually wouldn't have thought of a dedicated appliance-type cord.
 
Does this heater require a vent? Often these types do. Even if you are not in there all the time, make sure you vent it if required since the gases can build up and cause health or fire risks.

Your plan for power sounds fine using the 12 gauge. I would opt for buying a shorter cord, though.
 
I have a smaller space heater I use at work to keep my hands warm, I want to say it's 800 watts or so. The extension cord I use does get a bit warm, but not hot after running for 12 hours. I think you'll be just fine.
 
Originally Posted by wallyuwl
Does this heater require a vent? Often these types do. Even if you are not in there all the time, make sure you vent it if required since the gases can build up and cause health or fire risks.

Your plan for power sounds fine using the 12 gauge. I would opt for buying a shorter cord, though.

Venting isn't an issue. The ceiling isn't in great shape, so it vents a bit excessively into the roof/attic area for the entire garage footprint (there's probably a solid 1-2 square feet of just 'hole' in the bathroom ceiling). The roof/attic area also has a large opening in the main area ceiling (at least 6-8 square feet). The entire garage is about 1,100 square feet. It gets too much air, hence the need for a heater.
 
1.59v drop over 100 ft of 12ga wire vs 1.26v over the 50ft length of 14ga wire.

Use the 14ga. At 600 watts resistive (Which is what a space heater would be) you're looking at 5 amps of draw at 120v.

12ga voltage drop is 1.588v per 1000 feet or .1588 ohms for your 100 foot run.
14ga voltage drop is 2.525v per 1000 feet or .12625 ohms for the 50 foot run.

Less voltage drop equals less power dissipated in cord resistance. You're better off with the 14ga.
 
Last edited:
Originally Posted by ctechbob
1.59v drop over 100 ft of 12ga wire vs 1.26v over the 50ft length of 14ga wire.

Use the 14ga. At 600 watts resistive (Which is what a space heater would be) you're looking at 5 amps of draw at 120v.

12ga voltage drop is 1.588v per 1000 feet or .1588 ohms for your 100 foot run.
14ga voltage drop is 2.525v per 1000 feet or .12625 ohms for the 50 foot run.

Less voltage drop equals less power dissipated in cord resistance. You're better off with the 14ga.

See, this is what I was talking about regarding technicalities. BITOG has some smart members.
thumbsup2.gif
I'll use the 14.
 
Someone is going to call me out on this.

The 14ga cord is going to be dissipating 3.024 watts per foot.
The 12ga cord is going to be dissipating 1.908 watts per foot.

Its really a crap shoot at this point. You'd have to get in to how the cord is laying and coiled as to which one is going to dissipate heat better and run warmer.

You should be well within safety margins using either one of them in my opinion, especially at 600 watts.
 
Last edited:
Originally Posted by OilStasher
Originally Posted by zrxkawboy
I'd buy a short, "appliance"-type extension cord.

Completely fair point, but I don't have one. Before I buy one of those, I'd much rather buy a 'smart outlet' for ~$15 and just control it over wifi. But I also didn't want to pay a $15 lazy tax (see above), so $3 was much easier to swallow. I already owned the extension cords. Thanks for the advice though. I actually wouldn't have thought of a dedicated appliance-type cord.


I meant to use the cord with the "smart outlet", not in place of it. A heavy cord that's 6' or 10' long with have much lower resistance than a 50' or 100' cord.
 
Originally Posted by zrxkawboy
Originally Posted by OilStasher
Originally Posted by zrxkawboy
I'd buy a short, "appliance"-type extension cord.

Completely fair point, but I don't have one. Before I buy one of those, I'd much rather buy a 'smart outlet' for ~$15 and just control it over wifi. But I also didn't want to pay a $15 lazy tax (see above), so $3 was much easier to swallow. I already owned the extension cords. Thanks for the advice though. I actually wouldn't have thought of a dedicated appliance-type cord.


I meant to use the cord with the "smart outlet", not in place of it. A heavy cord that's 6' or 10' long with have much lower resistance than a 50' or 100' cord.
Right, but the cost of an appliance cord would probably be equal to or exceed $10, plus the $3 for the thermocube... You're then approaching the $12-17 cost of a wifi smart outlet. Instead of buying the cord, I'd rather just buy a wifi controlled smart outlet and eliminate the need for an extension cord altogether. The heater has a cord long enough to reach the standard outlet.

Call me cheap, that's fine (of course I'm not implying you are). But I have a stiff viewpoint against lazy tax. So the smaller the cost, the easier I rest knowing I paid *only* X price to be lazy. It has to be justified in my mind. I'm weird I guess.
 
Personally I would have a hard time trusting a $3.00 thermocube.. I think I would try to get some kind of quality thermostat.

Rod
 
It too has been my experience that molded plug ends tend to be the weak point rather than the wire gauge. A bad crimp on a connector will create a lot of heat.

Originally Posted by Donald
Check the ends of the extension cords after running the heater for a bit. The molded plugs/outlets can be cheap.
 
Originally Posted by Donald
Check the ends of the extension cords after running the heater for a bit. The molded plugs/outlets can be cheap.
I guess I should tie up loose ends. Here are links to my 50' 14-gauge cord and my 100' 12-gauge cord. Highly recommend both btw, especially for the $14.99 and $17.49, respectively, that I paid for them
grin.gif
. Based on my experience with them, contrary to the price I paid, there is nothing cheap about these. Edit: I've used cheap orange cords my whole life until these. Never liked any. These however, well, I might cry if these get cut or damaged. Best ones I've ever owned.
 
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