BC electrical code question.?
Question:If I am running 3700 watts of heater in total is there a distance maximum that I can go with my wire. I want to go to one heater with 2000w of heat and then to another with 1700 w. Do there have to be on different circuits or is one okay. Please only answer if you are sure. thanks
Answers:
if you want to figure out the current of all heaters divide 3700watts by your voltage which should be 220 volts will give you 16.80 amps,you will need a #12 wire,and two 20 amp 2 pole circuit breaker,they could be controlled from the same thermostat,but you have to hook them up in parallel with each other meant that a two pole breaker would be needed for the 220 volt cir cut tandem was not the right word,and 12 Gage can handle the voltage drop my heater are are all hooked up 30 to 40 feet from breaker panel and it passed the electrical inspection,and nec code.i two am licensed and passed the new your master electrician test which is the hardest in the country, just because a person has a license does not always mean that they know what they are talking about.
Seeing how luka is a fully qualified Canadian electrician, I will defer to him. However, I would have asked you the distance of the run to see if there would be a voltage drop with the 12 ga wire. I also would have recommended a 2 pole circuit breaker because a tandem breaker shares the same buss tap and would only supply 2 legs of the same 120 volts and not 240. Assuming that is the voltage in BC. Of course luka would know that. Then I would have informed you that I am not familiar with the Canadian or BC or local codes or even the voltages you have there and suggested that you contact a real electrician in your area and ask him or her. That would be much safer than asking here. Sorry I can't be of more help to you.
John is right on about that. Do your heaters have their own thermostats or controlls? Makes a diference on how they are wired. Generally 80ft makes the upgrade in wire size, but that could be considered on a known load. If your going to run over 16.5 amps then go to a 10 Gg wire and 30amp 2pole breaker. Increasing the wire size up 1 size on a known load will save electric in the long run as well.
First I would convert the watts to amps drawn by these heaters and come up with the amps. For example#12 wire can handle 20 amps,which is a minimum size for equipment in a lot of states, I dont think you can run both heaters on the same line because of code requirements. Second ,every 100 feet you run wire the voltage drops in that line,if your talking long distances ask your supplier he has a chart you may have to up your wire size what ever it turns out to be. Your heaters should give the the amperage rating. As always get the advice of a professional if your not sure of your self.
One thing that I'd like to add is that allthough everyone says that you can run 20amps off of a #12 wire, the code also says that you should only be at 80% ampacity at any time. So 80%of 20 is obviously 16amps and if your heaters are pulling more than that, you want to jump to the next size wire and perhaps a 25 amp breaker. Another thing is, where exactly are the heaters and are they going to be considered a continuous load. Defined by a load where the maximum current is expected to continue for three hourse or more. If these heaters are next to windows or doors of heavy traffic area then I would say that there is a good chance that they would be on for three or more hours. Therefore you have to rate any continuous loads at 125% 3700 watts where I live would be calculated at 15.42 amps because we are supplied with 240volts everywhere. It can fluctuate but I haven't seen anything under 237 in a long time. It used to be 220 but they have seemed to hike it up to 240 and even 250 over the years. But 3700watts divided by 240 gives you 15.42, which is under the 80%. However, if it's a continuous load then muliply that by 125% which gives you 19.28 amps which you shouldn't put on a #12 wire, especially if it's a good distance away from the power source. Also that is more than 80% of the breaker, you'd need to feed it with a 25amp breaker. Then if voltage drop comes into play with over a 5% voltage drop on your feeders to the farthest heater, you've got to upsize you're wire again..it's all code, calculations and safety. You just need a meter to check your voltage drop, figure out if they'll be running longer than 3 hours and check your actual voltage so you can make an accurate amperage calculation....and if all else fails, call a liensed electrician. May not be as inexpensive, but he or she should know how to do their job, afterall it is what they are paid to do. Hope that I helped and sorry..I said that there was just one thing that I wanted to which turned into several. Just trying to help.
Licensed Electrical Contractor
The resistance of #12 wire is 2 ohms per 1000 ft which means that if the heater is 500 ft away ( 1000 ft complete circuit is there and back) from the source and carries 16A, the voltage drop is 32V. Since this is a purely resistive load is merely reduces the heat output of the heater by about 25%. It still works. The same is not true for motors; the wire size must be increased to keep voltage drop below 3-5%. There is no technical problem with running 2 heaters in parallel at any distance as long as the wire size is adequate for the circuit breaker.
However, if it were my house, I would run separate circuits to each heater and increase the wire size if the heater is more than 300' from the panel. Some municipalities actually require separate feeds for room heaters if they are in different rooms.
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