Electrical Question

[MTboatguy]

Hey guys, I am putting in a 240 volt forced air heater in the shop and what I want to do is wire the plug for it instead of a hard wire, it is a Cadet smaller 5000 watt forced air that I am putting a 30 amp cord on and then would like to wire a home run to the box through a thermostat and then to a plug that matches the cord on the heater, that gives me the ability to move about the shop, which is on about 400 SF.

Is is kosher to put the thermostat inline before the plug? it is a simple single pole line break bi metal T-stat, I can't think of anything that would become a problem, but figured I would check as I am not an electrician, I have done quite a bit of wiring over the years, but always like to double check.

Thanks.

 

[alldodge]

I don't see an issue, only difference between this and base board heater is this moves around. Would want the heater to have a thermal limiter, but most do

I would use 4 blade twist lock plug with 10AWG cord.

Not an electrical either

 

[MTboatguy]

I am using a dryer plug that locks in that has a 10/2 cord, which will be just as if I am hooking a dryer up, the plug will be a home run to the box on a 30 amp twin pole breaker, the heater has a limit switch build in and pulls just over 20 amps based on the documentation I received from Cadet.

 

[alldodge]

The 10/2 with ground is old design for dryers, they all use 4 wire now. The ground and common separate at the breaker panel. Cadet does make a 5KW portable which uses 3 conductors, but in most cases this is designed to be double insulated.

https://www.lowes.com/pd/Cadet-5000-Watt-Portable-Electric-Garage-Heater-with-Thermostat/4712809

Don't know which you have but if its one that is mounted to the wall then this may not be the case. Guess I would look at the installation instructions. Which model is it?

 

[alldodge]

Take that back, dryers remain 3 wire, its stoves that have gone to 4 wire. You should be good

Told ya I wasn't an electrician

 

[StarTed]

I checked the math. 5000 divided by 240 is slightly over 20 amps considering unity power factor. Most breakers and outlets are rated 80% so you'll need a 30 amp circuit. The dryer plug should work fine from an electrical capacity point of view. 10 gauge wire is appropriate for up to 30 amps so that is fine as well.

I'm not up on code as I was an utility electrical worker before retirement.

 

[MTboatguy]

20.83 amps to be precise, 30 amp circuit, if we go 80% of 30 amps = 24 amps, so everything should be good to go, wiring code changed in 1996 from 3 to 4 wire for ranges, but not the dryer type hook ups and my home was built way before then, the heater is a Cadet CEH model http://cadetheat.com/products/garage-heaters/CEH/CEH005-P

Looks a lot like their current portable, but I paid a lot less for a close out than they want for their current portable model, we had a True Value HD store that was closing them out for $150, with the parts I have had to buy, I will still be less than $210 and the new one they have is over $300 and even on ebay sells for over $350.

I was just wanting to make sure that a single pole t-stat before the actual plug would not cause any problems and I can't see how it would.

 

[StarTed]

Since 2 wires are hot to ground I believe the t-stat should be a 2 pole type. A single pole type will shut off the heater but one leg will remain hot. That could be a problem if one is not careful. I don't think that would be legal per code but that is beyond our expertise.

 

[MTboatguy]

Well based on what Cadet published in their papers with the heater, they offer both a single as well as a double pole built in T-stat for this heater and my other Cadets are run on single poles, I figured it would be good to go.

This is a quote from their paper work

"For single-phase only, a line voltage thermostat is required for operation. For three-phase, a two-stage or modulating thermostat is required. A Cadet wall thermostat is recommended for ultimate control and comfort."


I purchased a Cadet/Honeywell single pole for this install

 

[levittownnick]

I would have some concern that the thermostat can handle the current (25 Amps) as well as being two pole to switch both hot legs.
My other thought is about the cost of electricity, I know it would tear a hole in my pocket.

Stay warm,
Nick

 

[sam am I]

https://www.amazon.com/Packard-C230B-Pole-Contactor-Voltage/dp/B001KGSJ74

 

[StarTed]

Well based on what Cadet published in their papers with the heater, they offer both a single as well as a double pole built in T-stat for this heater and my other Cadets are run on single poles, I figured it would be good to go.

This is a quote from their paper work

"For single-phase only, a line voltage thermostat is required for operation. For three-phase, a two-stage or modulating thermostat is required. A Cadet wall thermostat is recommended for ultimate control and comfort."


I purchased a Cadet/Honeywell single pole for this install

I don't see anything about single pole. It says single phase. There is a difference.

If your house is on a three phase supply you most likely have 208 volts instead of 240 volts. Mathematically that is 120 volts times the square root of 3 (1.732).

The safest thermostat would be a low voltage one controlling a contactor (or relay). The line voltage t-stat should be 2 pole for 240 volts or 208 volts. A single pole t-stat should only be used on 120 volts or to control a contactor.

 

[bigdee]

Your fine. You can use a cheap baseboard mechanical thermostat.....typical price is around $20. Most are rated to handle 5kw. 10/2 with ground is all you need. Dryers are 4 wire because they have a neutral and need the fourth wire for a ground. Older code allowed 3 wire if neutral was bonded to cabinet.....that is no longer allowed.

 

[MTboatguy]

I have single phase wiring, Meter is marked 3W 240 V, this is one of the t-stats that cadet recommends, it is a single pole.

http://cadetheat.com/products/product-models?product_id=121

They also say this one can be used, this is the one that I have

http://cadetheat.com/products/thermostats/T410

I am not installing a 24 v low voltage on this heater, although it does have the ability to do that

This is the heater itself

https://www.platt.com/platt-electri...strial/Cadet/CEH005P/product.aspx?zpid=161513

 

[MTboatguy]

I would have some concern that the thermostat can handle the current (25 Amps) as well as being two pole to switch both hot legs.
My other thought is about the cost of electricity, I know it would tear a hole in my pocket.

Stay warm,
Nick

Power is not to bad, I already have two Cadet 240 v in wall heaters in the shop, they just are not big enough when it gets really cold, they are the small com pak in wall 1500 watt heaters, to slow to heat the volume and just don't move enough air. they are wired on a completely different circuit, so they can be independently controlled from the new heater I am putting in. Eventually I will take them out and use the 5000 watt forced air only.

 

[StarTed]

Electrically it'll work just fine.

The only problem would be if you poked around inside the heater with the t-stat off there could still be power at the heating element from the other hot leg that is not broken. Seriously I don't think you're inclined to do that.

Since you plan to have it on a plug you're even less likely to get into a hot wire since you'll unplug it first.

Enjoy the warmth.

My shop is too big to heat that way. I can barely keep it from freezing during cold spells by firing the wood stove once or twice a day.

By the way, I grew up in Montana spending 21 years without electricity so that is one of the reasons I went into the electrical trade. Now I'm spoiled.

 

[MTboatguy]

I never work on a hot circuit, learned that lesson many years ago! :facepalm:

This heater will only be plugged in when in use, which is one of the reasons I wanted a forced air unit, quicker heat up times when I am actually in the shop, instead of turning them on and waiting a few hours to get up to where I can at least work with a coat on. I have some gun projects I need to complete and I can't wait until it gets warm outside again.

 

[alldodge]

I would also suggest a double pole

 

[211libwtfo]

The only reason why stoves and dryers are 4 wire systems now is because most of them have integrated fancy display screens and options which require 120v or 12v power and to transform 240v you’ll need a neutral.

 

[211libwtfo]

And as stated previously the 5kw double pole tstat is perfect for your application