[Ryland]

The other day I bought one of the Black & Decker electric meter monitors that clamps on to your electric meter and gives you a read out of it's readings via a remote hand held display, it's not as accurate as I would have liked, it reads in 100 watt increments so any time the total loads are under 100 watts shows up as -0- it is nice however because it will let me read what my water heater is using, my electric stove or if I have 3 40 watt light bulbs on it will give a readout, it will also track the lower loads and give me a total used over a given time and tell me what my estimated end of month bill is going to be in either KWH or $ and give me a total of what I have really used, it will also allow me to do a tare on my usage so I can then flip my stove on, or whatever and get a more accurate reading.
So I hooked it up and it seemed to be working, it showed 300 watts used (my room mate was finishing up a tile grouting project with a big work light) then a little while later, after the work light was off I noticed it jump up to 500 watts! 5 minutes on 10-15 minutes off, now our house is a duplex so we have two meters, the meter this was on has the furnace, water heater, some lights, door bell, no fridge, no freezer, no normal household loads, the water heater timer was off, the furnace breaker was off.
So anyone have any ideas as to what this mystery load is? I'll be borrowing a clamp on amp meter in the next few days to test each line for that 4 amp load, but I'm interested in seeing if anyone can guess.