Adding a 220V circuit to my garage

[Greg Portland]

Does anyone have anything to add?

You should check the code to see what type of wire needs to be connected to the 220V heater... the proximity to high heat will add additional requirements. It probably also matters if the heater is permanently mounted or not.

[Adam Cormier]

Hey guys,


Just to add to this:


I made a mistake, it will actually be a 240v circuit I am adding, not a 220v.


The heater I am installing is a Fahrenheat FUH5-4 which has the following stats:


-240v
-5000 watt
-21 amp (at full capacity 17,065 BTU/Hr)


After the helpful advice and talking to a friend, I went to HD and purchased some NMD 90 Romex 10/3 orange (well, looks more orange than red to me) wire for my heater and a 30amp double pole circuit breaker. As per the advice, I take it this should be sufficient and meet code for my heater.


With respect to the installation, my main panel is located on the wall in my garage and I am planning on running 5 feet of the cable through the top of my main panel (still has 3 unused holes to run wire through from the top) to a dryer receptacle box rated for 250v/30amp which I will install. The wire will be hidden behind the drywall. So, to clarify on this, the receptacle will be 5 feet higher than my main panel, but directly in line with it (this way I don't have to route the wire through the 2x4's and also because it is the ideal spot to place my heater). I have decided on doing this instead of running it over the drywall and having to deal with conduit.


I also purchased a 10 gauge dryer power cord which I will attach to the heater and then plug into the dryer receptacle which will be approximately three feet away. The dryer power cord is rated 250v/30amp.


Does anyone see any problems with this installation? Also, I have added a picture of my main panel which you can see is only half full and is rated for 125 amps. Sorry about the orientation of the photo's, I couldn't get them to attach properly. But, of course, the left side is the top side.

As always, thanks so much for the assistance!

[Steve Meliza]

Physically your panel may be a little over half full, but all of those tandem breakers add up to 22 branch circuits if I counted correctly. None the less, you've probably got plenty of capacity left over for the heater in addition to the other "hotel" loads.

Don't be afraid to work in the panel without killing the power at the main breaker. Just stay away from the bus bars in the middle and don't mess around the black wires any more than you have to. I was just working inside my main panel this past weekend and never for a moment was it unsafe, and in my panel there are exposed connectors from the power meter so even if I tripped the main breaker I'd be working around exposed hot terminals. My view is I'd rather have good lighting and see what I am doing rather than trying to do a quality job in the dark without being zapped while juggling a flashlight.

Remove all jewelry before you start and only work with one hand as much as possible. The one hand rule keeps you from touching a live wire with one hand and a grounded object with the other which creates a path for current right through your chest. Bring the NM 10/3 into the panel, using a clamp in the knock out hole to hold the NM in place. Strip off the sheathing to about 1" inside the panel and trim the wires to about the right length. Connect the ground and neutral wires to the same buses that you see the other wires using and the black and red wires to the new 30A double pole breaker. With the breaker in the "off" position snap it into place. You'll probably need two hands to lock the breaker into place, but you don't need two hands inside the panel to connect the ground and neutral wires.

As long as the NM is behind the wall I don't think you'll have any code or inspection issues.

[Adam Cormier]

Hey all,


I just wanted to say thanks for the assistance with this. I just finished my install and had a quick consult with an electrician. It turned out great and the heater (Fahrenheat FUH5-4) works fantastic! Within 5 minutes I could already tell a difference in my shop (its about 5* celsius today). Here's a picture:

[Don Jarvie]

Adam, that heater needs to be hardwired. I have a similar heater, the Dayton G73, which is basically the same thing and its hardwired. The reason is the heater pulls pretty much the full currant and the plugs will fail after a while.

All you have to do is remove the plug from the wall and replace the cord with 10g wire. I used 10g armored cable going from the wall to the heater. Once you get sick of going up and down to set the thermostat you can replace the one on the heater with one on the wall.

[Adam Cormier]

Adam, that heater needs to be hardwired. I have a similar heater, the Dayton G73, which is basically the same thing and its hardwired. The reason is the heater pulls pretty much the full currant and the plugs will fail after a while.

All you have to do is remove the plug from the wall and replace the cord with 10g wire. I used 10g armored cable going from the wall to the heater. Once you get sick of going up and down to set the thermostat you can replace the one on the heater with one on the wall.

Hey Don,

Thanks for the reply. I will admit that I didn't think that the receptacle and power cord would be the weak link in this system. I was initially going to hardwire my system and I do have enough 10/3 NMD90 left over to go this route (I'd need to get some conduit to keep with code of course).

But, before I make this change, I would like to solicit some additional responses. The reason being is that both the power cord and the receptacle are rated for 30A, 250V. At full power (5000w) the heater draws 21A. The power cord is actually made from 10/3 similar to the NMD90 (it's a Range power cord). Also, the store that I purchased the heater from actually gave me the option of purchasing a power cord but I declined the offer as I was thinking I was going to hard wire it when I initially purchased the heater.

I appreciate any additional comments.

[Don Jarvie]

When I looked at the heater it looked very familar and I noticed you used a plug I looked it up on Northern tool and it said to hardwire it. When you think about it the heater is on a lto to heat the room and will cycle to keep the temp up so its on longer than everything in the shop. The plug and outlet aren't designed for that type of draw so they tend to heat up and eventually fail aka burn up.

I don't see any reason armored cable wouldn't work fine. It will protect the cord and will be flexible to run it along the ceiling. I got a solid box cover and put a hole in it and attached the cord. No issues except for a defective thermostat on the unit so I put a wall thermostat and disconnected the one one the unit. No more up and down.

[Steve Meliza]

I live in a house with 50 year old stove and dryer outlets that working just fine. The duty cycle is surely not too unlike a room heater so I don't see why a cord plug and outlet that is never disconnected and reconnected would fail just from the heat of 21A through a 30A rated outlet. I guess one way to check if the outlet is heating up is to let the heater run for an hour or so then feel the cord near the outlet and see if it is getting warm.

[Steven Wayne]

There is no reason to hard wire that heater. The NEMA L6-30 plug and receptacle are rated for 30amps, continuous current. If you hard wire it, then you will have to unwire it when you decide to move it, if it needs replaced, or any other reason to move it. Additionally, the chances a lay person will create a high resistance connection with 10ga wire and wire nuts it much greater than when wiring in standard outlets.

[Joseph Tarantino]

Don't be afraid to work in the panel without killing the power at the main breaker. Just stay away from the bus bars in the middle and don't mess around the black wires any more than you have to. I was just working inside my main panel this past weekend and never for a moment was it unsafe, and in my panel there are exposed connectors from the power meter so even if I tripped the main breaker I'd be working around exposed hot terminals. My view is I'd rather have good lighting and see what I am doing rather than trying to do a quality job in the dark without being zapped while juggling a flashlight.

congrats to the OP on getting his heater installed successfully. but i'd like to interject a thought here. i know electricians routinely work in live panels, but amateurs who need guidance form others, like the OP noted inthe opening post, would be better served killing the main to work safe within the box. i use a head mounted light ( a much cheaper version of this: http://www.homedepot.com/webapp/wcs/...&Ntpc=1&Ntpr=1 ) so i'm not fumblinig with a hand held light and a screwdriver. it takes less than 1 amp to disrupt the electrical rythms of the human heart. the higher amperages normally associated with 220v can do a lot of damage quickly. accidently groundinig a 30A dryer line or AC handler line in a live panel, when it could have been avoided by killing the main, could really ruin one's day. i always believe in safety first.

[Steve Meliza]

I would argue that it depends on the panel design. The OP's panel appears to be designed such that the live wires from the power meter are covered so tripping the main breaker will leave no exposed live conductors. In my panel design tripping the breaker puts me in the dark and still leaves exposed live wires and terminals. So I will concede that the OP would have been safer to trip the main breaker considering the panel design.

It takes more like 60mA to kill, but it needs to pass through your heart to be deadly. If you lick your finger and jamb it between the two buses you'll get the nickname "9 fingers", but you'll live. My feeling of safety comes from a father who was an electrician for many years before he retired and his teaching me that you always work on wiring as if it were live (eg. never put both hands in a panel). If you work in a electrocution conscious manner all of the time it doesn't matter if the wires are dead or not, you'll live to see tomorrow.

[Don Jarvie]

There is no reason to hard wire that heater. The NEMA L6-30 plug and receptacle are rated for 30amps, continuous current. If you hard wire it, then you will have to unwire it when you decide to move it, if it needs replaced, or any other reason to move it. Additionally, the chances a lay person will create a high resistance connection with 10ga wire and wire nuts it much greater than when wiring in standard outlets.

There has to be some reason why the manufacturer is recommending its hardwired. If they wanted you to use a cord there would be details on the type of cord, plug, etc.

[Adam Cormier]

I decided to shut the main breaker off just to be extra safe as I haven't worked in a main panel before. That being said, Steve is right. My main panel design is such that the main breaker and live wires coming into the box are covered.

As for the "to hardwire or not" issue. I have been checking on line and it seems that many people have done both types of installation.

I decided to contact Marley Engineering directly and when asking if hardwiring is a must, here is the reply:

"This unit is UL Listed as a hard wired heater, not a portable. Anything that could happen wouldn’t be covered under the UL, warranty or safety of the product."


Now, I don't know enough to refute or support this but I may just go out and get some armor cable and replace the power cord part of my installation with the AC90 going from the unit to the junction box.

[Steve Meliza]

There has to be some reason why the manufacturer is recommending its hardwired. If they wanted you to use a cord there would be details on the type of cord, plug, etc.

I didn't see anywhere in the instructions where it says to hardware, but it does only show hardwiring methods which would be the most common way to wire up a heater like this. However, a manufacturer not explicitly endorsing an option does not rule it out or we'd not be able to yank the cords off of tools and hardwire them.

Adam: Do they understand that the heater is screwed to the ceiling and not being used in a portable application?

Edit: It seems that this has more to do with the product being UL listed as opposed to would it work or is it safe. Being hardwired ensures you don't unplug it and haul it into your bedroom on a cold night (as if you could). There is nothing magical about NM over a power cord and outlet.

[Adam Cormier]

I didn't see anywhere in the instructions where it says to hardware, but it does only show hardwiring methods which would be the most common way to wire up a heater like this. However, a manufacturer not explicitly endorsing an option does not rule it out or we'd not be able to yank the cords off of tools and hardwire them.

Adam: Do they understand that the heater is screwed to the ceiling and not being used in a portable application?

I didn't specifically advise them of that. That may be why I got the response that I got from their engineering department. As you can tell, the response didn't have any explanation at all, it was just a statement. I asked for an explanation but unfortunately, I didn't get one.