Space Heaters = Power Quality Headaches

It's the time of year when space heaters begin appearing under desks, in alcoves, and in cold corners of offices in homes and commercial spaces.

"Looking for the space heater" is often my first check during a power quality audit in the winter - because electric space heaters are often the culprits in many power problems. 

• Fuse blowing or circuit breaker tripping
• Voltage drop problems
• Overheated connections or receptacles
• Neutral-ground voltage issues

A typical space heater will draw 10 - 12 amps at highest setting, and sometimes higher. This is close to the maximum rated for a 120 VAC, 15 Amp receptacle or circuit - which often also feeds lighting, office equipment, computers, etc. So a circuit or receptacle that has been perfectly adequate all year long is suddenly a problem. Coupled with laser printers (another power quality culprit) and it's a wonder anything works in the office this time of year.

If you need a space heater, check to see if you can get a dedicated outlet or circuit to power it - so that its current draw (and resultant voltage drop) do not affect your sensitive equipment. Remember that receptacles are often daisy-chained, so the empty outlet you find to plug your heater in may still be on the same circuit. And that same "daisy chain" may also be the point of failure - connections or splices in an upstream box or receptacle may be the place where the space heater added load causes a failure.

Here at the PowerLines home office, we've installed a dedicated 15A circuit - to run the space heater in the winter, and the air conditioner in the summer.