clearing fault on micc

[wattsup]

Fault on micc, one leg of two-core down to earth.

Anyhow big probs cos fixed / glanded into conduit box in concrete ceiling...supposed to be phased and tested before, the fault magically appeared after!

Ideas what to do and get out of hole before boss finds out

We settled on one guys idea who had done it before and worked...

wang 240v down it on 30A rewirable it may clear...

.....yep blew the pot out of the ceiling!

Just talked to him on phone, have to laugh about it now

So if any of you guys are faced with the same prob, try a 5A first -;

 

[wattsup]

yes absolutely serious engineer, btw please explain why the experiment is flawed?

 

[wattsup]

Bodge? If its clear, its clear...or maybe you know down the line all clear always clear?

Are you paul daniels?

 

[Engineer54]

yes absolutely serious engineer, btw please explain why the experiment is flawed?

I'm not even going to grace this with an answer!!

 

[Engineer54]

Bodge? If its clear, its clear...or maybe you know down the line all clear always clear?

Are you paul daniels?

I've been in this game long enough to know that little statement can come back and bite you in the arse, especially when talking about MICC pot faults. Blowing an earth fault apart in a MICC pot that you can't inspect is NOT a good idea ...Full Stop!!!

And you don't have to be a Paul Daniels or a clairvoyant to know that!!

 

[mechelec]

I have in the distant past removed pots to check. IR test still showing phase to earth fault. I was shown a trick that has worked on several occasions especially if the Pot has been twisted slightly when gland was tightened, give the conductors a pull with a pair of pliers directly inline with the MICC to pull them straight IR test again and bingo fault gone (sometimes) Fit new pot fill with compound and retest.

 

[Engineer54]

I have in the distant past removed pots to check. IR test still showing phase to earth fault. I was shown a trick that has worked on several occasions especially if the Pot has been twisted slightly when gland was tightened, give the conductors a pull with a pair of pliers directly inline with the MICC to pull them straight IR test again and bingo fault gone (sometimes) Fit new pot fill with compound and retest.

Yep, that's was always a good idea to try, before taking a faulty pot off!! Makes a lot more sense than trying to blow a short apart, that's for sure!!!

 

[wattsup]

Yeah that sometimes does the trick mechelec.

Please grace me with an answer engineer, surely you have been in the 'game' long enough to know experiments explain reasons.
btw using !!!! doesn't phase me (no pun intended)

 

[mechelec]

Yep, that's was always a good idea to try, before taking a faulty pot off!! Makes a lot more sense than trying to blow a short apart, that's for sure!!!

On the LV distribution network it is common practice when a fuse has blown in the LV pillar to bang 2 or 3 fuses onto a short circuit fault to clear it and it does work sometimes other times it develops into an OC fault other times the flames come out of the footpath and lets us know where the fault is lol.
If the fuse wont stay in then the fault finding gear comes out and the real work starts.

 

[Engineer54]

Yeah that sometimes does the trick mechelec.

Please grace me with an answer engineer, surely you have been in the 'game' long enough to know experiments explain reasons.
btw using !!!! doesn't phase me (no pun intended)

It's a fool hardy experiment, to say the least and you could do that a 100 times, and then one time will give you a completly different result!! I don't really understand what it is, your trying to prove with this so called experiment...


I don't know about you, but i have never been taught nor have i ever tried foolhardy experiments such as this, especially using the house wiring and it's accessories...


I have been forced to do things in the past, that wasn't exactly good practice to keep a factories production running. But whatever bad practice fix was done, it was corrected as soon as that production shift was over!! Not left in place, in the hope that it would be alright/hold forever more...

 

[Des 56]

To take things a step further,why don't we just get rid of overload and fault protection and blow our way out of problems willy nilly

I know its easy to say after the event, but in my experience and opinion, the fault remedy being touted should not have arisen,it should have, without exception, been picked up long before this drastic action would need to be considered

The insulation resistance tester needs to be in the tool bag with the pyro tools, ready for use after each cable was terminated, without fail
There said it

 

[somersetsparks]

On the LV distribution network it is common practice when a fuse has blown in the LV pillar to bang 2 or 3 fuses onto a short circuit fault to clear it and it does work sometimes other times it develops into an OC fault other times the flames come out of the footpath and lets us know where the fault is lol.
If the fuse wont stay in then the fault finding gear comes out and the real work starts.

Haha..
Reminds me of the first time I was howed inside an old lv pillar when I was an apprentice..... every fuseholder was black with carbon!
Like you say though easier to trace Open circuit.

 

[Knobhead]

On the LV distribution network it is common practice when a fuse has blown in the LV pillar to bang 2 or 3 fuses onto a short circuit fault to clear it and it does work sometimes other times it develops into an OC fault other times the flames come out of the footpath and lets us know where the fault is lol.
If the fuse wont stay in then the fault finding gear comes out and the real work starts.

Good fun until you get the idiot foreman I had. I’m trying to find a fault on an LV OH live. I had a gang of lads watching the line as I re-closed the switch, fortunately it was night so should have been easy to see. Tried it a 3 or 4 times when the foreman showed up playing merry hell when he sees the pile of blown 400A fuses. “Get me some 16mm” which he proceeds to strip one strand of it out, “there a 100A re-wireable fuse”. He fits it across the fuse bridge. “Right now try that, better than £100+ a time for fuses”. You can sod off you close it! Fortunately I’d got to the far end of the switch room when he did. I’d heard about the effects of ionised air and vaporised metal in a bus bar chamber, and I never want to see a practical demonstration of it again! 1MVA switchboard totalled, he was a nervous wreck, then just put the cream on the cake one of the lads came it tell me he’d seen a flash on one of the poles. We were shut down for three days for some reason? He had his authorisation ticket revoked.

 

[wattsup]

domestic, me neither engineer, i'm industrial minded and taught ..and will always be so, yuk t&e -)

 

[alarm man]

loose connection...pah sorted...

 

[wattsup]

'It's a fool hardy experiment, to say the least and you could do that a 100 times, and then one time will give you a completly different result!! I don't really understand what it is, your trying to prove with this so called experiment...'

I guess some peeps don't read the full thread, err yes it should have been tested, err yes it should have been phased out. But it was not, so stuck. The experiment is to prove your theory wrong, it can work and indeed does so, maybe 25% of the time. I'm not arguing the ins and outs of 'dodgy practice'

All i'm saying is your statement 'once an earth fault, always an earth fault, is fundementaly flawed. And can be proven, by my dodgy experiment