The installation instructions for this double oven read:

"This oven requires a separate, grounded 4-wire, 240V (AC), 50 Amp service with its own circuit breaker. Installation must comply with National Electric Code... We strongly recommed connecting this oven to No. 8 gauge copper wire."

Here is the question: Doesn't a 50 Amp circuit require #6 gauge wire? Why are they recommending #8 gauge wire when, according to my knowledge, #8 is only used for 40 Amps or less?

Any clarification would be greatly appreciated! Thanks in advanced!

According to the NEC, a #8 wire can handle 50 Amps but only if that wire is THHN (or equivalent) and is pulled as single wires (75 degrees C). If you are using Romex (NM cable) which most houses have, then you must use the 60 degree C column which shows 40 amps maximum on #8 wire and so you would have to use a 40-Amp breaker to protect the #8 wire. A double oven wall unit does not receive any exceptions from NEC 220.55 so you must use the nameplate rating or the manufacturer's instructions. Using 6/3 Romex (NM Cable) with a 50-amp, double-pole breaker is the best way to go.

According to the NEC, a #8 wire can handle 50 Amps but only if that wire is THHN (or equivalent) and is pulled as single wires (75 degrees C). If you are using Romex (NM cable) which most houses have, then you must use the 60 degree C column which shows 40 amps maximum on #8 wire and so you would have to use a 40-Amp breaker to protect the #8 wire. A double oven wall unit does not receive any exceptions from NEC 220.55 so you must use the nameplate rating or the manufacturer's instructions. Using 6/3 Romex (NM Cable) with a 50-amp, double-pole breaker is the best way to go.