After a short between two phases
crabtree polestar BS4293 rcd incomer
- Thread starter 333rocky333
- Start date
Not sure really what happened, but it was scary stuff.
The bottom was still live as it was straight off the meter with 160amp fuses.
I had just found the outgoing neutral loose and in the process of tightening, there was a big bang and it started arcing across underneath the rcd.
It hissed and banged and caught fire for approx 10 minutes before two of the phase fuses blew.
The bottom was still live as it was straight off the meter with 160amp fuses.
I had just found the outgoing neutral loose and in the process of tightening, there was a big bang and it started arcing across underneath the rcd.
It hissed and banged and caught fire for approx 10 minutes before two of the phase fuses blew.
The aftermath, the blue phase had totally come away
My guess would be there was a bit of loose metal in the DB (possiblly a wire offcut or similar) which happened to cause a short term short between the phases. I suspect this bit of metal was quickly vaporised leaving the arc which burnt up the board and eventually blew the service fuses.
Was the RCD adequately rated? Not easy to tell now! The loose connection may also hold the key to it, if there has been a heating inside the device which has damaged the internal wire insulation, the disturbance caused by tightening the neutral may have been the straw which broke the camels back.
Yikes 
Did you soil yourself?
Did you soil yourself?
K
kai
A bit related to this incident, the electricity main under this pavement was a bit overloaded to the point that the underground joint overheated, ruptured, and shorted out across two phases, blowing a hole in the pavement in the process - luckily nobody was hurt - the first I was aware of it was that our row of offices were all without power, becasue the substation fuses blew!
RF
Did you notice it was the rcd from the other post.
I had to take the earlier pictures for the insurance claim for the over voltage.
That was before it happened.
spark 123
The rcd was only 100amp 100ma fed with 25 mm tails from connecter boxes also teeing off with 25mm to a second same type board,the connector boxes fed with what looked like 35mm from a 200a head with 160a "J" fuses in.
This did not seem good to start with.
The board had to come and replace the fuses after, to get the rest of the site back on.(after the fire brigade left)
I remember once pressing the reset on a power breaker socket and that exploded, so I think I may be jinxed with RCD's.
I too wondered if it was internally damaged or on its last legs, possibly accelerated due to the original problem, over the years it had also been run and possibly overloaded, with a full load of industrial catering equipment.
This was all now redundant since the 90's according to the staff, so I presume the rcd had never been touched for over ten years.
Till I disturbed it maybe.
Must say it was the scariest and most embarrising day of my career.
The flash burnt my hand , but thankfully that was it.
The cut out was the other side of the fire, and was one with the four knurled nuts , two wire seals, and inside was the porcelein holders with the two wing nuts to remove them.
There was no safe way to get in and pull them, the room was about 8foot by 3foot,
So I stayed outside behind the firedoor and fired the co2 onto it, it went out for seconds then just arced and reignited.
Them 160 a hrc's took a lot to blow.
Did you notice it was the rcd from the other post.
I had to take the earlier pictures for the insurance claim for the over voltage.
That was before it happened.
spark 123
The rcd was only 100amp 100ma fed with 25 mm tails from connecter boxes also teeing off with 25mm to a second same type board,the connector boxes fed with what looked like 35mm from a 200a head with 160a "J" fuses in.
This did not seem good to start with.
The board had to come and replace the fuses after, to get the rest of the site back on.(after the fire brigade left)
I remember once pressing the reset on a power breaker socket and that exploded, so I think I may be jinxed with RCD's.
I too wondered if it was internally damaged or on its last legs, possibly accelerated due to the original problem, over the years it had also been run and possibly overloaded, with a full load of industrial catering equipment.
This was all now redundant since the 90's according to the staff, so I presume the rcd had never been touched for over ten years.
Till I disturbed it maybe.
Must say it was the scariest and most embarrising day of my career.
The flash burnt my hand , but thankfully that was it.
The cut out was the other side of the fire, and was one with the four knurled nuts , two wire seals, and inside was the porcelein holders with the two wing nuts to remove them.
There was no safe way to get in and pull them, the room was about 8foot by 3foot,
So I stayed outside behind the firedoor and fired the co2 onto it, it went out for seconds then just arced and reignited.
Them 160 a hrc's took a lot to blow.
I think you did the right thing TBH.
If you had opened the cutout and pulled the fuses with an arc load like that on them you could have been in an awful lot more of a mess.
If you had opened the cutout and pulled the fuses with an arc load like that on them you could have been in an awful lot more of a mess.
could have waited for the board too pull them here
As far as I remember there was no harmonized there, they were mostly 4 core sy flexes, and black cores, I assume the blues you can see are the neutral cores.
All the mcb's were taped off over the cover and was a right mess.
We did not install nothing, we was there to find the fault, but unfortunately finished it off
http://www.diynot.com/forums/viewtopic.php?t=133491
All the mcb's were taped off over the cover and was a right mess.
We did not install nothing, we was there to find the fault, but unfortunately finished it off
http://www.diynot.com/forums/viewtopic.php?t=133491
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