I have a Masterbuilt 20070910 30-Inch smoker.
I'm patiently waiting for my first pork butt smoke to finish (eleven hours and counting) and thought I'd share the energy measurements I did today. I have a "Kill-A-Watt" power meter that lets me measure energy consumption. When the smoker is turned on, but not heating, it consumes only 1.5 watts. When the heater cycles on, it consumes about 800 watts, just like the label says. However, as you cook, the heating element cycles on and off, so you cannot simply multiple 800 watts by the hours you cook, and then take that number and multiply it by your kWh electricity cost to figure out how much electricity is used.
Fortunately, this meter accumulates the power used, including both 1.5 watts used when the heating element has cycled off, and also the roughly 800 watts used during the time the heating element is powered on.
It was 60 degrees outside today, and I adjusted the smoker temperature until my Maverick measured 245 degrees. My smoker runs too hot, so I ended up setting the MES to 233 degrees in order to average out at 245. I opened the smoker once each hour to mop, and that obviously caused the smoker to cool, and then consume extra power in order to get back up to temperature. During the last few hours, when I wrapped the meat in order to employ "the crutch" to get through the various plateaus, I didn't add chips or open the oven.
Here are the results.
The smoker used an average of 308 watts during the time when I opened the door every hour to mop. What this means is that the energy consumed is identical to a 308 watt device that doesn't cycle on and off.
However, once I quit doing that, the energy consumption reduced to 284 watts (average).
Through the first nine hours (I'm not finished yet), the total power consumed was 2.56 kWh. To calculate the electric energy cost, you have to multiply by your highest (incremental) electricity rate. Here in California, we have tiered rates, and in most months our "last watt" of electricity is charged at $0.40/kWh. So I've spent $1.02 on electricity so far on this cook, and will probably spend another $0.50 before it is all finished.
This is probably not all that useful to most people, but some people drink lots of beer as they wait for their smoke to finish; I'm an engineer, so I do calculations (and drink beer).