Yes im working on a live board. If you had read it, you would see that the terminal I was "poking" it into was of an MCB which was switched off. Thanks for your input tho.

Switched off or safely isolated?

Your testing/fault finding methods in the OP leave a lot to be desired to be honest.
There's no logical reason to be wrong in a garage board with it energised.
 
Well there were two faults after all.
1. The busbar was indeed loose and causing arcing when moved (although this still doesn't explain why, when I attempted to connect the live into the SWITCHED OFF, 16A MCB, it caused the lights to go out and the busbar to arc).
2. After noticing there was no earth to the garage DB....and racking my brains as to why somebody would use yellow as a live conductor (supply to DB was spurred off a socket in the main house via a 3 core SWA ((red, yellow, blue)). Anyway long story short, he had a dead short between live and earth, (trunk if lid jammed the cable) which obviously he couldn't be arsed to find so simply disconnected the red (live) and decided to scrap the earth and then use it as the new live! One of the best I've seen fair play!!
 
  • Like
Reactions: 2 people
Switched off or safely isolated?

Your testing/fault finding methods in the OP leave a lot to be desired to be honest.
There's no logical reason to be wrong in a garage board with it energised.

That's the problem when you've never worked on site. You do everything by the book. It doesn't always work like that I'm afraid my friend.
 
That's the problem when you've never worked on site. You do everything by the book. It doesn't always work like that I'm afraid my friend.

Not your friend!
I have worked on many sites, and appreciate that sometimes you have to bend the rules.

But a 2 way board in a garage isn't going to be one of those times when you can justify working on a live board.

To be honest your having to ask online about the arcing and lights going off when the MCB moves slightly incident suggests that it would be you who is short on knowledge or experience
 
  • Like
Reactions: 1 person
Deleted
 
Last edited:
heres a similar one i had on the 31st december in a rental flat.
water escape from flat above into bathroom ,tenant can't turn lights off.
gets there ,
the pull cord is broken off, the inside has seen bit off water but its dry.
goes to pull the 3036 fuse to change the pull cord hear a bit off a fizzle and the lights stay on with the fuse out!
WTF says i and pulls the cover off to the sound of more fizzling. remove the carrier and find about 2" of seal wire that some lazy arse has plopped on top of the fuse board has dropped down and shorted across the lighting and the next door outgoing terminals.
Remove seal wire and my back feed problem was solved.
never come across this one in all my years at the game.
never presume anything be the moral of the story
 
  • Like
Reactions: 4 people
..remove the carrier and find about 2" of seal wire that some lazy arse has plopped on top of the fuse board has dropped down and shorted across the lighting and the next door outgoing terminals....

Nice example of why the IP rating of the top surface of electrical enclosures is required to be better than sides and bottom.
 
  • Like
Reactions: 4 people
This was a recent weekend callout. House is about 15 years old, with no significant modifications, so I recon the busbar was installed like this from new.

Note that this is not high current stuff. All the breakers on the affected busbar are 6A. Two alarms and three lighting circuits. Quite surprised at how the busbar has been eroded away. Somewhat amazed that the occupants had only recently noticed anything wrong.

View attachment 31183
View attachment 31182
View attachment 31181
View attachment 31180
View attachment 31179

Probably hard to tell but the missing bit of the busbar will have been firmly 'welded' to the clamp on that last MCB. But nice but of damage there. I have had similiar that affected two breakers and to a lesser degree, client wanted me to leave them energised instead of replacing them. Talked them round by saying it's not like scraping the burnt bits of your toast off and then it's fine!
 
  • Like
Reactions: 1 person
There was one breaker in particular that you could hear the cage fall back as you picked it up, I think that was the Wylex family.

Which breaker is it that when you tightened them up, the cable clamp feels like the screw has become threaded and just won't tightened up? It's either Wylex or Crabtree, they changed the design in the end so that rather pull the cable clamp towards you it pushes away and clamps the cable or it could be the other way around?

I got hit with a whole load of these in one week after all the wholesalers had closed so bought some spares to keep on the van. Sod's law I haven't come across a problem with one since!
 
  • Like
Reactions: 2 people
Which breaker is it that when you tightened them up, the cable clamp feels like the screw has become threaded and just won't tightened up? It's either Wylex or Crabtree, they changed the design in the end so that rather pull the cable clamp towards you it pushes away and clamps the cable or it could be the other way around?

I got hit with a whole load of these in one week after all the wholesalers had closed so bought some spares to keep on the van. Sod's law I haven't come across a problem with one since!
Yes, it was either , Wylex or Crabtree . The cage was so loose it was full floating lol.
Real pain at low level.
Picture 3 of Handysparks post shows the fortuitous contact when it is not fitted properly.
 

Similar threads

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electric Underfloor Heating Electrician Courses Heating 2 Go Electrician Workwear Supplier
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

Advert

Daily, weekly or monthly email

Thread Information

Title
Fault finding. Mind boggling
Prefix
N/A
Forum
UK Electrical Forum
Start date
Last reply date
Replies
29

Advert

Thread statistics

Created
normanton,
Last reply from
ruston,
Replies
29
Views
3,810

Advert