ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
May I backfeed 3 phase transformer?
by dsk - 10/22/21 04:37 AM
Wire sizing
by gfretwell - 10/21/21 10:12 PM
GFCI's pops in large numbers
by dsk - 10/21/21 02:03 AM
Need some info on Japanese outlets, 200V 15A
by andey - 10/20/21 08:05 AM
nec 110.3 (B)
by watersparkfalls - 10/19/21 07:09 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 15 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#175118 02/22/08 11:27 PM
Joined: Oct 2000
Posts: 3,666
Likes: 2
Admin Offline OP
Administrator
Member
Quote
Hi guys.

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.

- DougW

[Linked Image from electrical-photos.com]

Admin #175123 02/23/08 12:08 AM
Joined: Oct 2007
Posts: 56
S
Member
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.


Shawn.

SP4RX #175127 02/23/08 01:30 AM
Joined: Jul 2007
Posts: 1,335
S
Member
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. smile


"Live Awesome!" - Kevin Carosa
sparkyinak #175147 02/23/08 12:36 PM
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
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.

Joined: Jan 2006
Posts: 558
R
Member
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.

A.D

Rewired #175176 02/23/08 11:28 PM
Joined: Mar 2004
Posts: 251
W
Member
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

WESTUPLACE #175177 02/24/08 12:03 AM
Joined: Nov 2002
Posts: 791
W
Member
Was that a "push and pray" receptacle?

wa2ise #175184 02/24/08 09:26 AM
Joined: Apr 2005
Posts: 200
H
Member
Looks like a standard Leviton, although it also looks like they used the "push-n-pray" terminals instead of the screw terminals. frown


Cliff
Hemingray #175199 02/24/08 07:16 PM
Joined: Mar 2007
Posts: 165
Member
Originally Posted by Hemingray
Looks like a standard Leviton, although it also looks like they used the "push-n-pray" terminals instead of the screw terminals. frown

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; 02/24/08 07:21 PM. Reason: Second thoughts...

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
togol
togol
NW In. USA
Posts: 421
Joined: September 2005
Top Posters(30 Days)
dsk 7
Popular Topics(Views)
284,761 Are you busy
217,372 Re: Forum
203,712 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5