Signs of insulation melting around tails

[brewlab]

Hello.

This is my first post so be gentle.

Im currently doing the final year of 2330 and already have 17th Edition and plan on doing 2391 asap.

As you might expect its the form filling and certification thats troubling me.

I had a look at the tails on a friends old bakelite DB and there were some nasty charred looking terminations and signs of the insulation having melting slightly where they entered the main switch on the DB. The damage looked very old and not a current problem.

My question is what would the correct classification of this issue if i were in a clients house? And how would i leave the installation if i were not able to fix that day??

Cant remember what size tails they were but the DB has 4 20A fuses.

My plan of action is to replace tails/increase to correct size if needed and check the fuses have the right size fuse wire in them. Anything else?


Many thanks in advance fellas, looking forward to getting to know you all.

BL

 

[Spazz]

Take a step back

You need to work out the current flow through those cables first - that will tell you what size MCB and cable you need
Table in onsite guide

Check all cables within that circuit to see if they conform

Change any cables as needed

Test and inspect

If you are changing the cable size then LABC needs to be informed


If you cant finish it that day then leave it in a safe situation so it can be left - isolated if the situation allows
No seeing the problem - means I cant comment really

 

[brewlab]

Thanks for the quick reply.

All the cable sizes are correct and loads within limits of the CB.

So assuming the supply tails size can handle the design current i could replace them without informing LABC??

What would the correct code be for this on the new forms?

Thanks again.

 

[Spazz]

I am not sure to be honest - hopefully another member will be able to answer that.

The tails should of been able to handle the current though

 

[D80]

Any signs of loose connections at the terminations?
Any signs of the fuses having been abused (nails, wire or the like being used instead of fuses?)

Are you able to touch any exposed copper on the tails at present when the DB cover is in place (don't do it! Just asking are you able to!)

 

[brewlab]

Well...the signs of loose connections might be the blackened cables, but they appear tight now.

Not checked the fuses yet. I was just fitting an extractor fan when i noticed it. (yes i know its notifiable)

Theres no exposed copper when the DB cover is in place.

 

[Silly Sausage]

Well...the signs of loose connections might be the blackened cables, but they appear tight now.

Not checked the fuses yet. I was just fitting an extractor fan when i noticed it. (yes i know its notifiable)

Theres no exposed copper when the DB cover is in place.

Bear(sic) in mind, an apparent tight connection maybe not one. The screw could be seized, loosen it off then redo.
A gentle but firm tug on the cable will ease the mind as well.

 

[Knobhead]

Is it a metal clad board? It’s just that you mention the burning is around the entry point to the board. It could be a case of eddy current’s causing heat build up.

[Edit] just re-read the OP, forget the above.

 

[Des 56]

If you have had burning of the insulation,its likely the terminals will be knackered even if you were to think of just remaking them
You need to have a good look at what you are going to reconnect to

 

[UNG]

Yet another one with no pics

 

[Silly Sausage]

Yet another one with no pics

I know. The men in charge should limit postings to a max of ten words per piccie.
It's not like its hard these days to shove pics on web.

That's me 3 or 4 photos light already.

 

[Geordie Spark]

Yet another one with no pics

........ or shovels, but it IS an Electricians' Forum NOT a Navvys' Forum !! :crazy:

 

[brewlab]

Apologies for the lack of pics. It was more an afterthought to ask you guys for your opinion.

Whilst i have you attention.......

Before joining a certification scheme, the only way to carry out work is to...

A. Only do work that is not notifiable
B. Get someone to sign it off for you
C. Get LCC/LBC to sign it off.

Im just wondering as NIC say you should have traded for 12 months doing electrical work before applying for registration (as domestic installer)??

I have traded for 7 years doing all kinds of work,extensions, basements, bathrooms, kitchens etc, but never notified any of it, except the extensions where i had it signed off by someone else.

 

[robsparky1975]

Apologies for the lack of pics. It was more an afterthought to ask you guys for your opinion.

Whilst i have you attention.......

Before joining a certification scheme, the only way to carry out work is to...

A. Only do work that is not notifiable
B. Get someone to sign it off for you
C. Get LCC/LBC to sign it off.

Im just wondering as NIC say you should have traded for 12 months doing electrical work before applying for registration (as domestic installer)??

I have traded for 7 years doing all kinds of work,extensions, basements, bathrooms, kitchens etc, but never notified any of it, except the extensions where i had it signed off by someone else.

Who has been notifying the works?

 

[D80]

Who has been notifying the works?

What works?:ihih:

 

[Spazz]

It is illegal to get someone to sign off your work

DONT DO IT!

Someone can however issue a PIR but that is not the same as signing off and wont meet LABC Regs.

 

[Des 56]

Whilst i have you attention.......


I have traded for 7 years doing all kinds of work,extensions, basements, bathrooms, kitchens etc, but never notified any of it, except the extensions where i had it signed off by someone else.

The jobs that came under part p of the building regs will not have been logged
There may be problems for the householder when they come to try to sell their property,on the other hand you may have got away with it, like many others,cross fingers and hope for the best

As stated by others, you cant get work signed off, or at least the spark is foolish for doing so

 

[brewlab]

My wicked ways are all in the past now anyway. I am on my way to being a proffesional electrician.

I dont know exactly how they were signed off, but they were, must have been a PIR.

So how does the DIYer get work done on his own house signed off? LBC?

 

[LineProducts]

Are the cable ends twisted together? Researching causes of electrical fires, I read an article that explained how when twist-ons fail it is often a few cms below the actual joint. It explained the science ....if its of interest let me know and I will try to find a copy to post.

 

[Knobhead]

Where are the cable ends twisted together? Researching causes of electrical fires, I read an article that explained how when twist ons fail it is often a few cms below the actual joint. It explained the science ....if its of interest let me know and I will try to find a copy to post.

If you wouldn't mind.

 

[needasparks]

Prob telling people to suck eggs but With tails its always best when installing to tighten the terminal then give them a really good shake (and i mean hard) to get the cores to settle then re-tighten. this then stops contact being made to only a few cores and lessens the chances of it becoming lose it time. Mr wiggy tip you won't get a college.

 

[LineProducts]

If you wouldn't mind.

Its taken a while but here is the reference:

"Long-term failures of twist-on connectors was studied by Béland [45]. When two copper wires were
joined by a twist-on connector without adequate tightening, he found that failures commonly occur
due to metal loss, but this always occurred “several inches” away from the connector, not at the
connector itself. This was discovered to be a corrosion problem. Overheating of the connector
liberates HCl gas from the PVC wire; the gas is corrosive and attacks copper. Over long periods,
metal loss occurs to the point that a connection can be completely severed"

from Citation: Babrauskas, V., phd, How Do Electrical Wiring Faults Lead to Structure Ignitions? pp. 39-51 in Proc. Fire
and Materials 2001 Conf., Interscience Communications Ltd., London (2001).

 

[Strima]

Took you a few months... :lol:

I never knew that, everyday is a school day etc etc etc...

 

[Knobhead]

Thanks for taking the effort to find the information.

I knew I was right as an apprentice refusing to use those things.