ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
by Rabbit. 03/20/18 08:23 PM
Recall notice: Southwire wi-fi wall switches
by sparkyinak. 03/15/18 06:03 PM
Goodman Manufacturing Recalls Modular Blowers
by Admin. 03/13/18 10:40 PM
MAAX Spas Recalls Hot Tubs and Swim Spas
by Admin. 03/13/18 10:29 PM
New in the Gallery:
Housebilding DIY wiring
SE cable question
Who's Online Now
0 registered members (), 9 guests, and 10 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Incorrect Lugs Used #121553
07/22/05 11:29 PM
07/22/05 11:29 PM
Trumpy  Offline
Joined: Jul 2002
Posts: 8,236
SI,New Zealand
Photo submitted by D Thomas
The attached photo is a hot joint on a 3phase motor isolator, the reason for the failure is that an incorrect lug (copper) was used to terminate an aluminium cable. As you can see in the photo the other two lugs under the tape are much larger, these are bi-metallic lugs.

[Linked Image]

Thanks mate.

Tools for Electricians:
Re: Incorrect Lugs Used #121554
07/24/05 07:31 PM
07/24/05 07:31 PM
Trumpy  Offline
Joined: Jul 2002
Posts: 8,236
SI,New Zealand
I was recently reading an article on Crimp Lugs used in electrical installations and apparently this particular problem is the most common cause of cable/connector failure, next to using the wrong sized connector.
Looks like this particular crimp lug has just corroded and burned away because of the higher resistance connection. [Linked Image]
This could have been a nasty failure had it gone un-noticed.

Re: Incorrect Lugs Used #121555
01/19/06 06:54 AM
01/19/06 06:54 AM
RODALCO  Offline
Joined: Dec 2005
Posts: 856
Titirangi, Akld, New Zealand
It requires the isolator to be replaced and white Ø cable extended and re terminated to new islolator switch to remedie this fault properly.

Same here too the Al cable needs enough surface area in the lug to have a low resistance connection between cable and lug

I have found it here many times too in distribution pillars and transformers.
Wrong lugs used to terminate to busbar or NZI fuses in transformers. or Cu droppers made to connect bimettalic lugs to and not enough surface area between lug and dropper causing hot spots.

The bimetalic lugs also rely on the surface area between lug and terminal to allowe for a low resistance surface hence the larger size of the eye.

Seen many times that solid Al 70 mm² cables just been srewed straight into HRC fuse carriers without any transition joint or joint compound used.

The product of rotation, excitation and flux produces electricty.
Re: Incorrect Lugs Used #121556
01/25/06 06:19 AM
01/25/06 06:19 AM
kiwi  Offline
Joined: Dec 2004
Posts: 354
christchurch new zealand
Cool Photos ! I've often wondered what that would look like when it fails. Ali cable in a copper lug. Who'd do that ?


2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
Bay Area
Posts: 61
Joined: August 2007
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 5
Admin 5
Popular Topics(Views)
244,544 Are you busy
181,668 Re: Forum
171,714 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.017s Queries: 14 (0.004s) Memory: 0.9598 MB (Peak: 1.0909 MB) Zlib enabled. Server Time: 2018-03-22 04:07:59 UTC