From a real world prospective, you are not likely to have a problem. It certianly is not a fire or shock hazard but I'm sure if you operated all 3 GDO's at the same time you might trip the breaker. Depending on what else you have on the circuit- air compressor, freezer or other larger appliances, you might trip the breaker when you use only one GDO.
So this guy has a 4 car garage- he/she can afford the additional circuit(s).
#97240 - 02/05/0611:10 AMRe: 210.23(A)(2) and 3 Car Garage
I have a three car garage, and I ran a single circuit to all three openers. I fully expected to have to run a second circuit for the last of the three openers. But, the circuit held when I opened or closed all three at the same time. (added one opener at a time over several years) I did run a separate circuit for the lights and receptacles.
Are you trying to avoid installing a panel in the garage? The NEC makes it clear that if you run a multiwire branch circuit (sharing the same neutral with two hots) to a detached garage, that it constitutes a single circuit, and a panel (and the ground rods) are not required.
#97241 - 02/06/0611:43 AMRe: 210.23(A)(2) and 3 Car Garage
I also have 3 openers on same circuit. The only time I have tripped a breaker was when I had an elect heater plugged into same circuit I was using table saw and someone else was using skill saw at same time.
It also had no affect on doors because they are on circuit by themselves.
#97242 - 02/06/0608:48 PMRe: 210.23(A)(2) and 3 Car Garage
It is an attached garage, and my main concern was NEC compliance regarding the aforementioned article. As far as performance, it is probably a crap shoot. If someone operates all 3, the CB might not handle the starting currents.
I ran a 2nd circuit.
#97243 - 02/06/0609:24 PMRe: 210.23(A)(2) and 3 Car Garage