Sizing Space heaters.

[dedi]

I have generators that have very low mega readings when idle. The problem has been narrowed down to the cable and insulation box on the generator. I want to add space heaters in the box that is about 3'L x 2'W 6'H, and opens at the top into the generator. I am thinking 3 500W space heaters, spaced evenly inside the box connected across 208V. Is this sufficient to heat up the box?

 

[edison123]

At 3.5 KW, you will fry the cables. Try something like 100 W. You just want the cable to be 2-3 deg C above ambient dew point to prevent moisture condensation.

 

[pennpoint]

edison123
I could be wrong, I think "dedi" meant to say 3each 500 watt heaters. Still too much heat (me thinks).

pennpoint

 

[edison123]

do a google on "anti-condensation" heaters for more info.

3x500 W or 3500 W, you'll still fry the cables.

 

[bgisborn]

Anytime heaters are used you don't want them to run wild. local thermostatic control should be secured to the cable-not just monitoring-but actual controlling thermostats for the heaters. In addition, a manually resetable high temperature cutout for the heaters should be in series with the thermostatic controls and have its own separate sensing transducer at the cable location.

 

[pennpoint]

dedi
As previous posts have eluded, you do not need allot of heat. Just 100-200w could be enough.
I have used Hoffman brand enclosure heater. These are self regulating and designed to do just what you need to do. May I suggest you seek them or Rittal or other electrical encloser mfg. for advice. This is real simple.

Best Regards
pennpoint

 

[cuky2000]

Consider install a unit with inline thermostat with more than one stage to maintain the appropriate temperature in the box. In that way if the heater is oversized the risk of overheating will be minimized.
Beware that space heater could be used not only to prevent freezing in winter time but also to prevent condensation and moisture accumulation in other seasons.
The enclose table could help you to determine the minimum size of heater.

For additional details, see the enclose site.

http://www.heatersplus.com/enclosure.htm