OT: Electrical Question Options

[McMark]

How many amps would the circuit below draw? What if they were 2 kW, 3 kW and 4kW?

Anyone care to explain how you found your answer? Electricity stuff makes me feel totally inept. It always feels like I'm on the verge of understanding things and then I realize I don't know anything. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

I'm trying to wire up the heat lamps for the paint booth and I need to know what size wire we'll need and what size breakers to use. (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

EDIT: It's 220v.

[dmenche914]

It would still be the same current draw, as the heat lamps have a rated wattage,and voltage, thus no matter how you wire them, you still have the same power requirement in total.

If they were however in series, if one went open circuit, they would all lose power. Kind of like cheap xmas lights where when one goes bad, and the whole set dies. You normally do not find circuits in buildings wired in series for this reason, one fault, and the whole thing goes down.


Also since this is a paint drying booth right? Some consideration should be given to explosion proof lamp fixtures, junction boxes, and if located in potential fume areas, the switch and breaker.

My thought on the heating lamps is if at all possible, maybe wire them on seperate switches, so you can control the amount, and location of heat, also save energy if all lamps are not needed.

if so, then all the lamps could be on one 40 Amp breaker, with heavy wire to handle say 40 Amps at 220 volts (this is more than is needed, but will allow future expansion without new wire / breaker, really only 30 Amp is needed) The 40+ amp rated wire however need be ran the entire system, even if you used three switches to divide the current into three 2000 watt sub-circuits.

The reason why you would keep using the heavy 40+ Amp rated wire, even on a section which is designed for only one third the entire circuit load (2000 W or about ten Amps at 200 volts) is that you must never use wire in any branch of a circuit that is rated less than the fuse or breaker protecting that circuit.

If you do not follow this rule, and use a smaller wire in one part of the circuit, that smaller wire in effect will become the fuse if you get a short circuit on that line. When a wire becomes the "fuse" it gets hot, and starts fires. The breaker amperage rating must always be the "weakest link" in the "chain" of the circuit. You would not be building to code otherwise, it is a safety issue.

The final circuit will be determined on if you will be running 110 or 220 volt heat lamps.

If 220 Volt, then 30 Amp minimum (recommend 40 Amp if available) breaker and wire rated higher than breaker amps for the circuit. Wire the two open ends on your diagram circuit too the 220 Hot, and Hot terminals. You can use one switch, but ideally it should be a double pole switch, as both wires will be hot, and you do not one wire still hot when switched off. So use a double pole switch, or use three of them, one on each 2000W branch.
A small breaker shut off box might be good

If 110 Volt, then wire the two open ends of the diagram off one leg of the hot and the other to nuetral using a 60 Amp (minimum) breaker, and wire rated at 60 amps. Also the switch must be rated at least at 60 amps! The switch need only be a single pole in the 110V circuit, as unlike the 220V circuit, one side of the 110V line is nuetral, there is only one Hot side, and the Hot wire is the only one that needs to be switched, so single pole here. Same option for one or three switches, all single poles.

You can see the advantage of the higher voltage 220V. lamps, they will require wire at half the rated amperage, that can save money in wire cost, also the switch need be rated at only half the amperage as that used on the lower voltage 110V.

That's why home ovens, and dryers typically run on 220V, cause they are high power users, that would require even thicker wires, and higher amperage breakers and switches if ran at 110V. Your 6kW heat lamps are in the power realm of electric ranges, and dryers, and should ideally be 220V, although 110V can be made to work.



One question???? I am assuming you are running on single phase. Are you? If you have three phase power (lucky you) you could wire the three branches on the lamps one on each phase and there are two methods of doing that, hot to hot, hot to hot, and hot to hot, verses hot to nuetral, hot to nuetral, and hot to nuetral ("Y" vs. "Delta" circuit types) You would be able to run 10-15 Amp breakers three each (usually sold as a three pole breaker) Or you could just run off one leg of the three phase, for all three lamps protected by one 30-40 Amp breaker.