This industrial establishment needed a receptacle for some of their equipment.
The breaker in the panel serves the pigtail- which exits the panel through the large opening, and just sort of "hangs" there. Should the door be closed, the next guy gets to "fish" it off the bussbars.
Yes, Rob, it does LOOK that way...but it does terminate at one of the two breakers that you see. (The other serves the receptacle next to the panel) What is also misleading is that, while this plug may look like a 240v "dryer" cord, it is not; it is a non-NEMA 125v/30a pattern used by the RV industry.
So, the breakers are a single 1-pole, 20 amp and a single 1-pole 30 amp.
#121623 - 08/04/0503:40 AMRe: Why Panels Have So Many Knock-outs (not)
Just a little side-note guys. I don't know, over the time that I've been here at ECNet, how many times I've seen plugs hanging half-way out of recepts!. Surely it must be a violation of some sort to have the plug, bear the weight of a heavy cord?. I'm not sure how long the pins are on these plugs, but wouldn't it cause burning of the mating contacts when current is drawn through the cord?. This sort of thing sort of winds me up a tad.
#121624 - 08/04/0508:20 PMRe: Why Panels Have So Many Knock-outs (not)
You are right to worry about half-out plugs. As far as I can remember, these were the sorts of things always used as examples of how home fires start.
If a plug is just barely making contact with the receptacle, and there is a sizeable load on it, the plug prongs can get red-hot. As you might guess, this sort of heat will cause the wire insulation in the cord, the receptacle, and the wires in the box to degrade, and eventually fail.
Just the sort of thing the AFCI was originally claimed to protect us from.....but that's another story.
One of the big differences between a quality device, and a residential one, is the amount of tension in the springs that hold the plug in. All devices will weaken eventually- but if a receptacle is used frequently, or is expected to hold against the weight of a substantial cord, getting a better device to start with makes sense.
#121625 - 08/04/0509:43 PMRe: Why Panels Have So Many Knock-outs (not)