Electricity conversion question

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We have an extension cord running out to the greenhouse/chicken house, which usually runs a water warmer and a light for the birds. As we are expecting an ice storm tonight and tomorrow, I wanted to get some heat in there to make sure the ice melts off and doesnt collapse the thing (its a hoop house) I now have 3 120 watt bulbs, a 1500 watt electric heater as well as the water warmer(which only turns on if it goes below 32 degrees) How do I know if I'm exceeding amperage?

-- Sue (sulandherb@aol.com), January 30, 2002

Answers

watts divided by volts equals amps. So no matter if you use 110 or 120 volts in the equasion you are exceeding a standard 15 amp household circuit breaker.

You may have noticed that almost no appliance eceeeds 1500 watts. If they are over they are less than 1751 watts.

What you have is a fire hazard, don't let us read about your burned up greenhouse tomorrow, start unpluging now.

-- Marc (toymeister@hotmail.com), January 30, 2002.


You are looking at close to 16 amps with the heater on. Here is a link to a chart.

cord chart regards

-- Ourfarm (ourfarm@noaddr.com), January 30, 2002.


Amperage is determined by dividing the wattage by the volts ie 1500watts = 120(volts)x 12.5 (amps) 1500/120=12.5 this is the heater amperage the lights amperage can be figured by the same method. This is OHMS Law and if any 2 are known in the equasion the other can be found. God Bless

-- Charles Steen (xbeeman412@aol.com), January 30, 2002.

Thank you all! Going to unplug a couple of lights now!

-- Sue (sulandherb@aol.com), January 30, 2002.

Just an after thought..with the cold outside u should be ok because the heat generated by the higher amperage will be disapated. Is the cord pluged into an outside receptical? If it is not running through a heated area the rating on it can safely be raised because of the cold ambient temp. The NEC (national Electrical Code)gives ratings for wire in conduit and free air... the free air has a higher ampasity than those in conduit because they disapate the heat generated a lot better. Hope I didnt confuse You. I am a retired Electrician. God Bless

-- Charles Steen (xbeeman412@aol.com), January 30, 2002.


oooooh! A retired electrician! I hope you lurk around here often!

BTW let us know what happens tomorrow. I would like to have a hoophouse next winter but hadn't thought of the snow problem. Don't the birds produce alot of heat themselves. Im in the south (tn) myself. where are you located?

-- Ann Markson (tngreenacres@hotmail.com), January 30, 2002.


We're in northeast CT. The reason I am concerned is because we got the largest one (10X48) and it has the slightest sag in the roofline. By the way, when you get yours, they give you a list of different wood to use for the support....go with the largest one. We didn't :( The snow we've had has slid off, but 25 birds don't producce that much heat! I've kept and coverd their poop in the house for the last couple of months to produce some heat....I guess now we just hope for the best.....and build a better chicken house next year. This thing was advertised as a great alternative coop, but when their is a full moon, they all sit on their perches staring outside!

-- Sue (sulandherb@aol.com), January 30, 2002.

change your lights to low watt 25ญญญ>40 depending on the size of building 1500watt heater should be good for 150 sq.ft. of bulding with no need of a water heater also light bulbs give off heat use one with a refector right over water, worked for me bucket did not freeze over

-- nick (ray@smpatico.ca), January 30, 2002.

Also, you do not want to exceed 80% of your breaker or fuse load. Which is 12 amps on a 15 amp breaker/fuse or 16 amps on a breaker/fuse. This is to allow for high current start up, such as when your electric heater first comes on. With the wattage you have given you have already exceeded a 15 amp breaker and at maximum for a 20 amp breaker.

Current draw will vary according to what the actual voltage is from the grid. Some places it is as low as 108 volts and some it is as high as 130 volts.

-- r.h. in okla. (rhays@sstelco.com), January 30, 2002.


Sorry that is suppose to be: and 16 amps on a 20 amp breaker

-- r.h. in okla. (rhays@sstelco.com), January 30, 2002.


Two issues come into play here. First is power and second is current carrying capacity. If you look at your heater is most likley will say DONT use with an extension cord. 15amps or 1800watts is the typical outlet. 2400watts is a 20amp circuit. These are not uncommon in a home but usually for special wired circuits or circuits in a garage.

Your 1500watts is close enough to the max power I would not want to add more any more devices to a circuit. Keep in mind your 1500watt heater may draw a little bit more since it most likley will have a small fan in it.

Your extension cord also MUST!!!! be capable of 15amps of power. MOST of your typical outdoor cords (orange coating) are not rated for 15amps and should not be used. Most heaters have a big notice DONT! use with extension cords for this reason. If your extension cord is not rated for high current DONT use it with the heater. WHile it may work, your going to risk fire

-- Gary (gws@columbus.rr.com), January 30, 2002.


Another consideration: Where is that extension cord plugged into? If it is plugged into a outside receptacle on your house, this receptacle could be in series with more receptacle inside your house. Therefore you would have to consider the amp load of anything that is plugged into them also. Sorry there is a lot of things to consider when figuring the amp load.

-- r.h. in okla. (rhays@sstelco.com), January 30, 2002.

I don't know how to figure it but I think that the length of the cord also comes into play the longer the cord the less of a load it can carry. gail

-- gail missouri ozarks (gef@getgoin.net), January 31, 2002.

Sue, You may want to re-think using the heater at all. As I understand it, your problem is the snow on the roof, not just the inside air temperature. Instead of trying to heat all that air, use heat lamps pointed at the roof (not too close) The radiant heat projected directly at the roof will keep the snow "moving" along down the sides. But a BIG word of caution here - If one lamp falls in the bedding (perhaps knocked down by an animal) it won't take long to start a fire!! Or if the heater gets bedding tossed onto it - same problem. Please be careful ....

-- TonyG (tony_granados@hotmail.com), January 31, 2002.

Gail your right about length having a factor also. It's called voltage drop. The longer the distance to the load the greater the voltage drop which will create more amp draw.

-- r.h. in okla. (rhays@sstelco.com), January 31, 2002.


Lots of good info on here but some of it is a little muddled.

More cable means more resistance which in turn means less current. Power is current times voltage so you actually use less power on a longer lead.

Thinner cable also means more resistance so ditto.

If you are using extension leads to handle heavy loads be sure that any excess lead is not coiled up otherwise the coiled bit will get hotter than otherwise.

-- john hill (john@cnd.co.nz), January 31, 2002.


Re: proper extension cord rating. A cord rated for 15 amps would be 14 guage wire. Typically, extension cords are 16 gauge.

Good luck

-- Rick (WV) (Rick_122@hotmail.com), January 31, 2002.


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