Bad day fault finding.

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I thought i would share with you all the crap afternoon i had. I got a call at 11 ish 'We have lost all the power to the security cabin'. I talked through the Rcd's Ect and was assured all was on so i had to drop what i was doing and go fix.

The job is a 4 acre site being used by a utilities company as their base/ store yard. The jobs less than a year old so this will be a no charge. I was on the other side of London and had to drive through the Blackwall tunnel to get there. Its a TT installation. I fed the site from 3 separate, 3 phase boards, each with a 100mA TD Rcd in-case of nuisance tripping.

When i arrived after 1 1/2 hour drive, the yard RCD had tripped so i reset it and it tripped again. It took me about half an hour to work out which part of the 4 acre site was causing the problem.

It was now pi**ing it down and i had to wear full PPE, hard hat ( in case a pigeon sh*t on my head ?) big heavy steel lined boots ( ideal for fault finding on a 4 acre site) Hi vis jacket and trousers. Of course, the fault was on a DB at the far opposite end of the yard. I first tested the neutrals to earth, as no breakers had tripped but was getting odd readings. Now the big problem, I narrowed down the fault to a lighting circuit ( which had no other RCD protection other than the 100 mA TD). I had tripped the RCD about 10 times now ( work out how far i had been walking to reset it) This lighting circuit fed 12 containers each with a 5ft fluorescent inside & each with its own PIR detector. The fault was on one of the lights but i could not test because the pir could not be energised due to the fault.

So every pir had to be dropped and each light tested, guess what- it was the last one. One of the chokes in the twin fitting had a almost short circuit to earth, enough to trip the 100mA Rcd but not enough for the 6A C type breaker.

I cut out the faulty choke and screwed everything back together. Its now 18.45 and i am knackered. Got home at 20.00. At least its chargeable as the containers were brought from another site.

 
If you had posted on the forum when you got there, we could have told you it was the last light fitting, it always is :)

Just clad you managed to get the fault sorted, and at least it is chargeable.

 
slips, its taught from an early age, its always the last one you check!

Final sentence is some consolation - chargeable.

 
Looking at it now, do you think it could have been done quicker? Maybe disconnect half of the PIR's and then switch on to see if it trips. Similar to splitting the circuit but live

 
So every pir had to be dropped and each light tested, guess what- it was the last one.
of course it was the last one. i doubt you would keep checking after finding the fault!

and at least it was chargeable so not that bad

 
Looking at it now, do you think it could have been done quicker? Maybe disconnect half of the PIR's and then switch on to see if it trips. Similar to splitting the circuit but live
Thats how i started, but decided it was quicker to drop every pir rather than walk the 4 acre site in the rain re-setting the Rcd

 
batty!

Now I love fault finding!

I would rather spend a day doing what Slips has just had to do than fitting sockets and lights in a domestic!

Each to his own I suppose!

 
batty!Now I love fault finding!

I would rather spend a day doing what Slips has just had to do than fitting sockets and lights in a domestic!

Each to his own I suppose!
Couldn't agree more, sets the men from the boys!

 
im on a pig of a fault in a domestic at the mo,,,hindered by the customers working hours

back there tomorrow

suffice to say sometimes its like pulling hens teeth to get the info you need from them

like 'can you show me where are all your sockets are'

i will take photos tomorrow and start a new thread and open up a discussion on my fault finding methods :eek:

 
and is it me or when a customer bangs a nail into a hidden cable causes a fault and calls you out then when you ask have you done anything recently they say ooooh nooo not us it just happened like that which you later find to be a load of tripe!! why cant people just be honest and say i hit a cable by accident it would save hours of trouble

 
i went to one a few years ago, phoned up syaing rcd has tripped and wont switch back on, get there starts taking ring main apart traing fault round house, spent 3 hours 6pm till 9pm on the evening, then again next day another 3 hours 8.39 till 9.30 am, finding where problem lead to, ended up being a picture had been put up directly behind the tv in lounge on the wall, above the double sockets for tv, owner said they knew nothing until i found that then admitted theyd put the picture up the day before hand, why not just say first up it would have saved 6ours messing about could have been in and out in 2 hours replace cable test and reconnect job done it just pi$$es me off.

 
and is it me or when a customer bangs a nail into a hidden cable causes a fault and calls you out then when you ask have you done anything recently they say ooooh nooo not us it just happened like that which you later find to be a load of tripe!! why cant people just be honest and say i hit a cable by accident it would save hours of trouble
and their money !!!!!

 
If they don't tell you they can't complain when the bill is so high!!!!! It's their problem

 
I had a similar one with a lighting fault a few years back. The owners swore blind no work had been done, no pictures hung etc. Eventually found the fault 10 hours later in a hall cupboard where shelves had been put up and drilled right through the cable. They moaned at the bill so i reminded them of my questions before i started, there reply was 'that was the other side of the house so i didn't think it mattered'

 
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