3 phase problem after spark did 5 year safety inspection

jimthegent · Dec 23, 2023

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

[ElectriciansForums.net] 3 phase problem after spark did 5 year safety inspection

suffolkspark · Dec 23, 2023

jimthegent said:
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

Why did the spark have the tails out for an inspection?

jimthegent · Dec 23, 2023

suffolkspark said:
Why did the spark have the tails out for an inspection?

No idea but it's a local council job so I assume because they can bill them for more dough

suffolkspark · Dec 23, 2023

jimthegent said:
No idea but it's a local council job so I assume because they can bill them for more dough

Are you sure he actually did remove them? He should have spotted a loose connection when checking all the terminals though, thats if it was that and not faulty contacts in the switch.

jimthegent · Dec 23, 2023

suffolkspark said:
Are you sure he actually did remove them? He should have spotted a loose connection when checking all the terminals though, thats if it was that and not faulty contacts in the switch.

Yes 100% he took them out and put them back in again

westward10 · Dec 23, 2023

I would say a dead short has occurred there.

jimthegent · Dec 23, 2023

westward10 said:
I would say a dead short has occurred there.

Yeah and what do you think caused it

westward10 · Dec 23, 2023

There is molten metal albeit it doesn't look like copper, the remains of something else?

snowhead · Dec 23, 2023

Looks like the Red clamp has squashed the cable and split the insulation.
That's allowed the copper core to touch the earthed metal backplate and or the screw holding the clamp.

If it was the cable lose in the terminal or wrong side of termianl clamp it would have fizzled and overheated for a while before ultimately failing.

As Westwood, it looks like a dead short, especially with the ball of copper

jimthegent · Dec 23, 2023

westward10 said:
There is molten metal albeit it doesn't look like copper, the remains of something else?

Yes the cover of the board was blown off and there's a lot of black soot all over the switches so clearly a lot of heat was generated

plugsandsparks · Dec 23, 2023

Cable clamp look suspicious....

jimthegent · Dec 23, 2023

snowhead said:
Looks like the Red clamp has squashed the cable and split the insulation.
That's allowed the copper core to touch the earthed metal backplate and or the screw holding the clamp.

If it was the cable lose in the terminal or wrong side of termianl clamp it would have fizzled and overheated for a while before ultimately failing.

As Westwood, it looks like a dead short, especially with the ball of copper

Yep now bear in mind all other tails and switches are pristine is there any votes for system overload the main fuse that blew into the building is also on phase 2

westward10 · Dec 23, 2023

It is a dead short. Can you show a more direct pic below the red clamp.

plugsandsparks · Dec 23, 2023

Not overload, short cct fault as WW states

jimthegent · Dec 23, 2023

westward10 said:
It is a dead short. Can you show a more direct pic below the red clamp.

plugsandsparks · Dec 23, 2023

Needs to be powered down and clamp removed, i can see it is already pinching the RHS cable sheath.

Once clamp removed photograph the back side of it, remove the LHS cable and photographc the back plain of board, should tell you everything you need to know, Merry Xmas

jimthegent · Dec 23, 2023

westward10 said:
It is a dead short. Can you show a more direct pic below the red clamp.

Hi no they can back and replaced the switch and tail and removed the offending bits

suffolkspark · Dec 23, 2023

Ah so its all sorted....

jimthegent · Dec 23, 2023

suffolkspark said:
Ah so its all sorted....

Seems the wire being nipped seems to be winning the vote can any of you guys see a situation were a nicely balanced 3 phase which was always well well under max amps would see just one phase go up like this

jimthegent · Dec 23, 2023

suffolkspark said:
Ah so its all sorted....

Yeah but the upshot was that we were running on 2 phases for a a good few hours the fans failed the temp in the building rocketed and a load of other problems as a result

jimthegent · Dec 23, 2023

plugsandsparks said:
Needs to be powered down and clamp removed, i can see it is already pinching the RHS cable sheath.

Once clamp removed photograph the back side of it, remove the LHS cable and photographc the back plain of board, should tell you everything you need to know, Merry Xmas

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 ?

westward10 · Dec 23, 2023

What did they say caused it.

jimthegent · Dec 23, 2023

westward10 said:
What did they say caused it.

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

jimthegent · Dec 23, 2023

westward10 said:
What did they say caused it.

I've attached a picture of were the feeds are they are the ones on the rhs blue ones

westward10 · Dec 23, 2023

jimthegent said:
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

That wasn't an overload that was a dead short, a short they created.

3 phase problem after spark did 5 year safety inspection

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