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.
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.
