Service entrance wiring burned but breaker didn't trip


Old 08-10-15, 12:53 AM
Thread Starter
Join Date: Aug 2015
Location: Philippines
Posts: 77
Received 0 Votes on 0 Posts
Service entrance wiring burned but breaker didn't trip

I would like to ask on how it happened that the wire burned and the breakers did not trip. The loads are welding machines and grinders. One thing that I thought is that the ampacity of the wire was not able to hold the current, for short, an under rated wire. Could you share your opinions regarding this incident?
Sponsored Links
Old 08-10-15, 01:17 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 21,119
Received 3 Votes on 3 Posts
If it's actually the service entrance, in the US it wouldn't be your problem...but I would guess either the correct torque on the connections or no anti-corrosion paste used? Scorched connections won't necessarily make a breaker trip.
Old 08-10-15, 01:36 AM
Thread Starter
Join Date: Aug 2015
Location: Philippines
Posts: 77
Received 0 Votes on 0 Posts
Sorry sir but it is not in the U.S. It is from Philippines. The service connection wires are burned but the main breaker did not trip. The load side wasn't damaged too. I am thinking what is the cause of this incident. I think the connections are good because they have used it before.
Old 08-10-15, 03:02 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 5 Votes on 5 Posts
What size service do you have, what is your main breaker size and what is the size of the entrance cable? If the cabling was too small for the load and the breaker was too large for protection of the cable, then the cable becomes your "fuse" and will burn before the breaker trips unless there is a direct short.
Old 08-10-15, 04:03 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,595
Received 200 Votes on 178 Posts
A breaker will trip on overload which is normally due to too much current flowing through the breaker. Heat is also a contributing factor.

Wires that are burned is almost always due to a poor connection. Poor connections can create a lot of heat, but depending on where it might not be enough to trip a breaker, especially on a main breaker with 100-200 amp rating.

Are the wires aluminum? If so, is there anti-oxidation past on them? A picture would be helpful.
Old 08-10-15, 06:23 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 43 Votes on 41 Posts
If you run welders, you know how much damage an arc can do even from a small welder. A loose wire in the electrical service works the same way. All it takes is for the connection to be a little bit loose, an arc forms, heat builds up, bigger arc, more damage, bigger arc... Significant damage can occur before there is enough amperage drawn to trip the breaker.
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: