Arrived at the FD yesterday and noticed an extension cord running the length of the bay floor. The departing Commander told us that the drop cord for the 1st line ambulance and the extrication engine had stopped working, but the other drop cord on the same circuit was still working.
As the "resident spark", I got detailed by our Commander to check out the problem. A check up top revealed 110 VAC from hot to the metal box, but nothing from hot to neutral. And the box was mounted in the "blind spot" between a support I-bean and the wall about 16" away, so I'm workng to the side. After searching through 6 panels in 3 different spots and trying about 15 breakers labeled "FIRE - SPARE" and "FIRE - APPARATUS BAY" (gotta love remodels, additions and remote generator panels) I was finally able to d/c the circuit and climb up to the ceiling.
As I neared the box, I recognized the smell. Suspicions confirmed after opening the box and finding this.
The FF who had installed this had fed the outlet on one terminal and then "daisy chained" to the next receptacle (for the engine). Not sure exactly how long it took, but my best guess is that the draw for the ambulance and engine finally heated the terminals enough to melt the receptacle, but over a long enough period of time to not be too obvious.
Needless to say, the new outlet is now fed off a pigtail, and the d/c clearly labeled.
It seems to me that these receptacles should each be on their own dedicated cct. If this wire was overloaded to the point where it ignited I don't see how pigtails will help. You decrease the current flowing in the pigtailed portion of the cct. but there is still a single conductor all the way back to the panel.
You should check this out as this problem could recur.
If I read your post right, it should have not melted. I am interpretting the the hot and neutral were landed on their respected hot/neutral screws then the wires from the second drop cord were landed on the second set of screws of the melted receptacle. If that is the case, then the outlet should have not melted like that. It is difficult so tell from the 2 dimensional picture. I would suspect a loose connection or a possible charging issue with one of the trucks. I agree with sp4rx that each truck should be on dedicated circuits. If the circuit failed and was not caught, two trucks could have been KO'd instead of one.
If a non-sparky was responsible for such an important conncection, I would start back tracking his or hers handy work. Remember that firefighters has a pyromaniac for an inner child.
I see this sort of thing on a fairly regular basis ... and I don't think the problem is caused by having the current 'pass through' the receptacle.
Sure, there's heat damage ... but I think we have to look deeper for the cause. Loose screws are always a likely suspect. For that matter, so are loose fitting plugs, partially inserted plugs, and some internal fault with the receptacle. Since everything is copper, heat will readily travel all over the insides.
The one thing I see wrong here is it appears the receptacle that was used was an el-cheapo residental grade device. Yes they are rated " 15A" but really when installed in a residence, they only ever see a few amps load at any given time and when these things DO fail its usually when someone has plugged in a space heater or window shaker and that wipes out the device. My choice would have been a commercial grade specification device at minimum. That may have helped remedy the problem simply by having better terminals, heavier contacts and a better retention of the plug.
I am doing a Fire Station remodel now. Here, each EMS bay has its own 30a 125v cord drop. All medic units have to be connected to shore power while parked to keep the AC operating to keep drugs stored cool. Robert
Looks like a standard Leviton, although it also looks like they used the "push-n-pray" terminals instead of the screw terminals.
It looks to me like a Leviton 5320. However, let's not forget that GE for a time distributed its own 5320, which was so close a copy of the Leviton that I expected Leviton to sue (maybe they did). If you look closely, you can see where the 'Quickwire' openings in the base were closed in to allow 14 gage but to prevent use of 12 gage. The picture is blurry, and I can't really say there are still leads in the undamaged plug-ins on the far side from the camera. The surviving plug-in toward the camera is clearly empty.
I used to use these routinely, taking comfort in the UL listing. These days, I go directly to commercial grade.
Last edited by Retired_Helper; 02/24/0806:21 PM. Reason: Second thoughts...