I have a small 8x6x6 greenhouse that is not close to the house and needs a greenhouse heater as I live at 9000' in Colorado. I will have to use an extension cord and the ones I have found say not to use them. Any suggestions?

I don't know of any electric heater where they say it's OK to use an extension cord. When we ran electricity to our greenhouse, we put a new breaker in our panel and ran Romex, approved for underground use, just inches under the surface of the grass, and then put a GFI outlet in the greenhouse. The Romex is buried only 4 inches under the ground and not in a pipe. This is not recommended, but since we know where the line runs, we know where not to dig.

I have my greenhouse heater, on a timer, attached to a heavy duty 100" extension cord that plugs in by the garage. Have done this for 5 years and had no problems.

cwalke said: I have my greenhouse heater, on a timer, attached to a heavy duty 100" extension cord that plugs in by the garage. Have done this for 5 years and had no problems.

When you say "heavy duty" what gauge are you talking about. If I did that, I would go with at least a 12/3, but most likely a 10/3 which is almost like plugging the heater into a regular outlet. Just curious.

I would advise that you think twice about using an extension cord, heavy duty or not!
There is a huge difference in using such a cord in Washington State versus 9,000' in Colorado.

All electric heater manuals say not to use an extension cord for a very good reason. The manuals do not say, "It is okay to use an extension cord if you figure out a reasonable way to get around the safety issue!" And "never mind if the cord causes a catastrophic fire, it will only burn for a short period of time!"

Have an Electrician bury a service line and do it the right way!!
Short cuts can shorten your life!!!

MoonShadows said: When you say "heavy duty" what gauge are you talking about. If I did that, I would go with at least a 12/3, but most likely a 10/3 which is almost like plugging the heater into a regular outlet. Just curious.

I just mean one of the orange cords that you can get anywhere...
We get LOTS of rain here all winter and about 2-3 good snowfalls.

cwalke said: I just mean one of the orange cords that you can get anywhere...
We get LOTS of rain here all winter and about 2-3 good snowfalls.

"One of the orange cords that you get anywhere" is probably 16- or 14-gauge wire. They are OK for Christmas lights, hedge clippers, etc., but totally insufficient for a heater. You want at least a 12/3- or 10/3-gauge wire if you are going to run a heater, and even that is not recommended, but it could work. If I was doing it, I would go no lower than a 10/3 cord, but a 100-foot 10/3 cord could run you $100-$150. (Lower the gauge, thicker the wire.) How far is the run?

MoonShadows said: "One of the orange cords that you get anywhere" is probably 16- or 14-gauge wire. They are OK for Christmas lights, hedge clippers, etc., but totally insufficient for a heater. You want at least a 12/3- or 10/3-gauge wire if you are going to run a heater, and even that is not recommended, but it could work. If I was doing it, I would go no lower than a 10/3 cord, but a 100-foot 10/3 cord could run you $100-$150. (Lower the gauge, thicker the wire.) How far is the run?

Well, I should add that my heater isn't a big burly one either...it's pretty small, like one you'd use to heat up a small room. It also doesn't run constantly...when temps get below 30 degrees I plug it in and as it's on a timer, it cycles through the night. My greenhouse is 6x8. I use a 100' cord and it makes the full distance between garage and greenhouse, with about 3 ' of slack.

Look at the "rating" information on the plaque attached to your heater. It should provide information as to how much electrical current it draws or needs. Then use an extension cord that comfortably meets or exceeds those needs.

You really should not be trying to convince us, or yourself, of what you can get away with in terms of a safe, proper electrical hookup.
One thing that you probably need to figure on is moisture, water and dampness. Does that enter into your thinking at all.
Consider too that so many household fires resulting in hundreds of fatalities and countless $$$$ in property loss occurs as a result of improper wiring or heavy load appliances running on improper extension cords, should point you in the right direction.

BigBill said: Look at the "rating" information on the plaque attached to your heater. It should provide information as to how much electrical current it draws or needs. Then use an extension cord that comfortably meets or exceeds those needs.

You really should not be trying to convince us, or yourself, of what you can get away with in terms of a safe, proper electrical hookup.
One thing that you probably need to figure on is moisture, water and dampness. Does that enter into your thinking at all.
Consider too that so many household fires resulting in hundreds of fatalities and countless $$$$ in property loss occurs as a result of improper wiring or heavy load appliances running on improper extension cords, should point you in the right direction.

Thank you BigBill for your advice. I am not trying to "convince" anyone of anything, I am just sharing my own experience with another person who posted a question.