Masterbuilt says in the manual to not use extension cords. However if you use a short 12 ga x 15' cord you shouldn't have a problem. I have been looking for a inexpensive 10ga either 15 or 10 foot.
As long as you have a 12ga or 10ga cord and there shouldn't be no problem. I have a construction grade 14ga 50' cord and I had problems with my controller, removed the cord and it worked fine. The most likely problem will be not getting up to temp, and possible controller issues.
My problem and why I want a cord is to move the MES away from the house so smoke doesn't come through the roof eaves. I want to eat my Q, not sleep in it. Solution, I taped up the two eaves closest to the MES, and now I just smoke away. However I would still prefer moving it 10' away from the house.
about 6 feet. As I mentioned a 12 ga cord even 50' shouldn't be an issue.
I will say that on my house built in early 70s I have a weak breaker on a 15 amp circuit which feeds the outside outlet where my MES is. Even if I use only the MES cord but I plug in a hot plate plus a spot light, it has tripped the breaker. So my problem is more house issue, not ext. cord.
I unfortunately have the same deal at my house. It was built in the 50s and it has the old screw in fuses instead of a circuit breaker. I already blew a fuse plugging in my pizza oven. I'm updating the electrical in the spring. The outdoor electrical is a bit newer (80s) and it was able to run my deep fryer on a long ext cord for 4 hours (150+ wings got cooked for Wild Card Weekend) without a problem.