3 phase problem after spark did 5 year safety inspection

[jimthegent]

Hi lads 5 year safety inspection the spark put the tails back and later line 2 of the 3 phase blew blowing the box off the wall and taking out the main fuse on the same line into the building can you all just say quickly what you think the spark may have done wrong ?
Cheers

 

[jimthegent]

......but if any other people want to chip in I'd like to get as much feedback as possible on this feel free to join in

 

[plugsandsparks]

Hi can't thank you enough for the advice what would photos of the back of the clamp and board show or what should I look for ?

Perhaps should have mentioned it. You are looking for - what looks like a poor attempt at welding.. You should see black burn marks either at the back of the red clamp or black burn marks on the backplane, the melted - either copper or steel is plain to see in the pic.
Its no big deal, *hit happens, whoever repaired it will know the real reason.
If you have an overload that blows the doors off you may wish to consider the efficacy of your overload devices, lol
Anyway, you can hardly expect to be told that the electrician who disturbed the cable clamp and cable made a total *ollocks, i may admit to it, if it was me, depends on how i feel on the day.
Its possible it was previously fitted to an inch of its life and the EICR guy just fitted it back without "being fully alert"

(generous hat off)

 

[jimthegent]

Perhaps should have mentioned it. You are looking for - what looks like a poor attempt at welding.. You should see black burn marks either at the back of the red clamp or black burn marks on the backplane, the melted - either copper or steel is plain to see in the pic.
Its no big deal, *hit happens, whoever repaired it will know the real reason.
If you have an overload that blows the doors off you may wish to consider the efficacy of your overload devices, lol
Anyway, you can hardly expect to be told that the electrician who disturbed the cable clamp and cable made a total *ollocks, i may admit to it, if it was me, depends on how i feel on the day.
Its possible it was previously fitted to an inch of its life and the EICR guy just fitted it back without "being fully alert"

(generous hat off)

Yeah cheers you've been a mine of info really appreciate it ....the contractors are claiming we overloaded the board but there's plenty of spare leads and sockets and the others bits look like they have been fitted yesterday after 5 years use and given what they say if it was dodgy they should have noted it in their inspection report they didn't because it wasn't.....that only happend after they left

 

[Diddy]

Im getting the feeling that the contractors are trying to get you/company to pay for them to come out and "fix" the result in the 1st picture?
I would say that the 1st picture should throw any opinions out the water with the evidence of a dead short.
What has puzzled me is how did it not happen while the contractor was on site and when they re-energised the offending board? Did they not re-energise ?
Even if it did happen after several hours use then id still say dead short and cause being poorly terminated cables including but not limited to the cable clamp itself. Pretty ironic that if they had been "rough" and missed out the cable clamp this wouldn't have happened....unless the tails were super loose even a few hours under a decent load would do the job of melting the insulation leading to a dead short fault.
It shouldn't be a problem if they have rectified free of charge...but if there is other costs such as down time and damage then im sure their public liability will do what it's intended for.

 

[jimthegent]

Im getting the feeling that the contractors are trying to get you/company to pay for them to come out and "fix" the result in the 1st picture?
I would say that the 1st picture should throw any opinions out the water with the evidence of a dead short.
What has puzzled me is how did it not happen while the contractor was on site and when they re-energised the offending board? Did they not re-energise ?
Even if it did happen after several hours use then id still say dead short and cause being poorly terminated cables including but not limited to the cable clamp itself. Pretty ironic that if they had been "rough" and missed out the cable clamp this wouldn't have happened....unless the tails were super loose even a few hours under a decent load would do the job of melting the insulation leading to a dead short fault.
It shouldn't be a problem if they have rectified free of charge...but if there is other costs such as down time and damage then im sure their public liability will do what it's intended for.

Hi thanks for you thorough reply no we didn't power back until later that day, the firm are trying to say we over load the whole system and the melted outer casing is as a result of the tails getting warm it's taken a year to get to this point and they are hiding behind a loss adjuster who isn't even using a qualified electrician to produce reports that are laughable

 

[suffolkspark]

Looks to me like it was loose, got hot, popped out (maybe it was under tension but the clamp wasnt on properly, clamp doesnt look right to be honest but ive never fitted that brand) and then shorted like the others spotted, and bang. All hard to prove, but as you say, if it was an overload why wasnt it mentioned in the report. Thats because it wasnt.

 

[marconi]

Please tell me what loads were connected to the blue and brown c form sockets. Were they 3 phase motors or transformers connected to the brown sockets?
If they were three phase were they 3 phase 3 wire ie neutral not used?
Is the L1cable at the bottom of the 3 phase dis board - 2nd from left- showing signs of overheating - it is discoloured.
What other site loads were powered during the few hours after the L2 Incomer fuse ruptured and the site was left powered just by L1 And L3 - your #20 refers. Amongst these other loads were there 3 phase 3 wire motors energised by L1 and L3 ?

 

[jimthegent]

Please tell me what loads were connected to the blue and brown c form sockets. Were they 3 phase motors or transformers connected to the brown sockets?
If they were three phase were they 3 phase 3 wire ie neutral not used?
Is the L2 cable at the bottom of the 3 phase board showing signs of overheating - it is discoloured.
What other site loads were powered during the few hours after the L2 Incomer fuse ruptured and the site was left powered just by L1 And L3 - your #20 refers. Amongst these other loads were there 3 phase 3 wire motors energised by L1 and L3 ?

Hi the red / brown are not used and haven't been for 3 years the only board in use was the smaller board to the right with the blue sockets . In short our servrrs and cooling system abd ventilation systems all ran on the L2 but was balance with the others It's only the unit cooling system that ran off that board so when phase 2 blew the fans ran on 2 phases for a short period then stopped the temp in the unit would have rocketed a number of pdu's also blew up and there's evidence of molten copper and plastic on these also the surge protection wasn't enough to take the surge and we suffered catastrophic data loss and most of our hardware has been comprised it did look like a house fire when we got in

 

[suffolkspark]

L2 in that three phase board looks like its got hot too?

 

[DefyG]

is there any votes for system overload the main fuse that blew into the building is also on phase 2

No, definitely not.

An overloaded board but it's run fine for 5 years and it just happend to blow a few hours after they wiggled the wires plus each phase is perfectly balanced with 9 feeds

The fault you show is of the top (input) of a single phase consumer unit. A 3phased balance load would not have any bearing on the fault IMHO.
The damaged cable is a 'red herring', I believe as the clamp being insulating material there would nothing to make a circuit and cause a 'short'.
I would think the DP Isolator has failed and there has been a L-N 'short' within the isolator, or maybe a stray strand!

 

[jimthegent]

L2 in that three phase board loo from the electrical

No, definitely not.


The fault you show is of the top (input) of a single phase consumer unit. A 3phased balance load would not have any bearing on the fault IMHO.
The damaged cable is a 'red herring', I believe as the clamp being insulating material there would nothing to make a circuit and cause a 'short'.
I would think the DP Isolator has failed and there has been a L-N 'short' within the isolator, or maybe a stray strand!

The clamp is mild steel

 

[plugsandsparks]

Only going to know for sure with photos of the back of the clamp and back plate, if there are no marks i would agree and internal failure of the isolator comes into play, then was it caused by a loose connection or an internal failure of the DP Isolator. I saw the split in the tail on L2 supply and blamed the clamp (until proven otherwise) - it possible the heat generated by a loose connection compromised the tail insulation, hence you would need to see the components to work out what went first.
However i think we all agree unless the CB in the TP board is welded shut, then ADS should have saved it from this mess if it was indeed overload. (assuming the SP board is fed from the TP board) - i cannot tell from pic

 

[jimthegent]

L2 in that three phase board looks like its got hot too?

Could that have come from the electrical fire in the box we had it was cleaned up but initially there was a load of soot and detritus all over the box

 

[plugsandsparks]

I cannot see a SP breaker in the TP board to feed the SP board, so do the tails go to the Henleys and then straight to the incoming fuse? - If so i assume (again) this is either a 80A or 100A TP supply?

 

[jimthegent]

Only going to know for sure with photos of the back of the clamp and back plate, if there are no marks i would agree and internal failure of the isolator comes into play, then was it caused by a loose connection or an internal failure of the DP Isolator. I saw the split in the tail on L2 supply and blamed the clamp (until proven otherwise) - it possible the heat generated by a loose connection compromised the tail insulation, hence you would need to see the components to work out what went first.
However i think we all agree unless the CB in the TP board is welded shut, then ADS should have saved it from this mess if it was indeed overload. (assuming the SP board is fed from the TP board) - i cannot tell from pic

Only going to know for sure with photos of the back of the clamp and back plate, if there are no marks i would agree and internal failure of the isolator comes into play, then was it caused by a loose connection or an internal failure of the DP Isolator. I saw the split in the tail on L2 supply and blamed the clamp (until proven otherwise) - it possible the heat generated by a loose connection compromised the tail insulation, hence you would need to see the components to work out what went first.
However i think we all agree unless the CB in the TP board is welded shut, then ADS should have saved it from this mess if it was indeed overload. (assuming the SP board is fed from the TP board) - i cannot tell from pic

We are never going to know that the contractor returned the next day replaced the breaker replaced the burnt out tail and clean the crime scene up they also removed the items which technically still belong to us