Electrical Help

[Shadow_Walker]

Looking for an opinion on issue having at home. Randomly Friday morning most of the electrics in the house went off, checked the fuse board and the RCD had tripped, I couldn’t get it to go back to on so flicked each MCB off and bought the RCD back on and then flicked each MCB on and it was the hob causing it.

 

So fast forward to today and have had an electrician round and after disconnecting the hob and just putting it on the hob isolater the fuse board is still tripping.

 

The issue is I have the hob in the middle of my kitchen island so the cable goes underneath the floor and then up the kitchen wall so it is not ideal. He has said he wants to test the cable which goes down the wall down where the cabinets were installed 4 years ago to see if a screw had gone through it years ago on install and only causing issues now. For this I need to have the cabinets removed at the top of the kitchen and there is no guarantee that that is where the issue is.

 

Anyone got any ideas or thoughts.

[mavhc]

Has the exact fault been diagnosed? All 3 wires tested for resistance, connectivity, leakage?

 

Then narrow it down where it's easier to access, floorboard upstairs for example? TDR to estimate position? https://wiki.diyfaq.org.uk/index.php/Finding_damaged_cables

[Shadow_Walker]

He didn’t say on this but he wanted the cabinets off where the cable down the wall runs as a starting point. This is why I asked here as did not seem right. He is thinking it could be a screw due to how tight the cabinets are to the electrics but the joiner I know was careful over 4 years ago.

[MatthewL]

It's not uncommon for a screw to be the cuase of this a number of years on but removing units off the walls shouldn't be necessary yet.

 

Any good sparky will have their multi function tester and be able to rest each circuit one by one and check them to rule them out and then once on the faulty circuit the should be able to pin in between two points based on calculations worked out (stuff I don't understand but have watched and seen it done on YouTube). A video on David Savery's channel did detail a similar process a few months back, cannot find the exact video and content isn't PG and might not be everyone's cup of tea but you can learn from what he's trying to get at.

[Andrew_C]

As I read this...

 

Sparks has already isolated which circuit is at fault. He suspects the most likely area of damage to be in the wall where cabinets are fixed. Time domain isn't (I suspect) going to be accurate within a meter or two over maybe 10.

 

Unless there is scope for damage under the floor (vermin?) I'd guess he was on the money.

[Chris_Cook]

Unless you have very old cable like the rubber insulated stuff, then it isn't going to just randomly break anywhere.

 

At this stage once you've isolated the circuit, you need to start looking where the cable was most likely damaged, or where work was most recently done.

 

It could be if the screw has gone into the neutral wire rather than the live that something touching the screw that is also touching earth could cause the trip. We've had that before with a notice board and a laptop trolley.

 

Your only other option really is to get the whole cable re-run, but then you still have to have to remove the cupboards.

 

I'm assuming they've tested whatever is plugged into that circuit.

 

If it is a screw through a cable, then it might be worth looking into cable zones in walls as there are strict rules now where cables should and shouldn't be run, and where you want to be really careful drilling. Not all tradesmen are up to speed on this. The Efixx youtube channel has a training video on this somewhere.

[Shadow_Walker]

As I read this...

 

Sparks has already isolated which circuit is at fault. He suspects the most likely area of damage to be in the wall where cabinets are fixed. Time domain isn't (I suspect) going to be accurate within a meter or two over maybe 10.

 

Unless there is scope for damage under the floor (vermin?) I'd guess he was on the money.

This is correct, only thing was he never used a tester for this he was just going on where the cable was run down the wall and then under the floor into the island.

 

There has been no diy in the house for over a year so doubt anything from that, I just found it strange how all of a sudden just happened randomly.

[Andrew_C]

This is how a "professional" electrician wired Mrs_C's kitchen...

 

 

Spot the point where the screw hit the cooker circuit. And was then twisted and taped.

 

To add, I'd done the vertical chace to repair PROPERLY.

Edited September 17, 2024 by Andrew_C

[elsiegee40]

Looking for an opinion on issue having at home. Randomly Friday morning most of the electrics in the house went off, checked the fuse board and the RCD had tripped, I couldn’t get it to go back to on so flicked each MCB off and bought the RCD back on and then flicked each MCB on and it was the hob causing it.

 

So fast forward to today and have had an electrician round and after disconnecting the hob and just putting it on the hob isolater the fuse board is still tripping.

 

The issue is I have the hob in the middle of my kitchen island so the cable goes underneath the floor and then up the kitchen wall so it is not ideal. He has said he wants to test the cable which goes down the wall down where the cabinets were installed 4 years ago to see if a screw had gone through it years ago on install and only causing issues now. For this I need to have the cabinets removed at the top of the kitchen and there is no guarantee that that is where the issue is.

 

Anyone got any ideas or thoughts.

 

For us it turned out the actual circuit breaker switch was faulty. We had eliminated everything else. Got the switch replaced and never had a problem since!

[ToyHeartsFan]

An electrician doing some work for my landlord managed to put a screw through a cable when he replaced a kitchen extractor fan which immediately tripped the RCD so he repaired it...

 

Fast forward probably more than a year and the RCD tripped for no appararent reason, switched all the MCB's off, reset the RCD and switched them back on one at a time until it tripped again.

 

It was the lighting circuit that also ran the extractor, pulled the spur fuse for the extractor and the RCD didn't trip.

 

When they fitted the new extractor fan instead of using one that was the same size or plastering the hole first they had used a piece of plywood screwed to the wall to mount the fan. Got the multimeter out and there was a short between live and one of the screws holding the plywood.

 

So the screw had been live since the electrician had fitted the fan, the RCD had tripped because it had been raining a lot so the normally insulated live screw was now imbedded in bricks that were damp enough to trip the RCD.

 

 

 

 

Is the hob isolator switch on the island or on the wall, if it's on the wall you could disconnect the cable there which would help narrow down where the issue is.

 

 

1. Kitchen fitter screwed through a cable -- my money would be on this as well but you should be able to check for a short between the screw heads and live / neutral if they are accessible

 

2. Cable under floor was some how damaged when it was fitted but has got damp so is now tripping the RCD

 

3. Rats, mice, squirrel under floor have chewed a cable

[ToyHeartsFan]

This is how a "professional" electrician wired Mrs_C's kitchen...

 

[ATTACH=CONFIG]72185[/ATTACH]

 

Spot the point where the screw hit the cooker circuit. And was then twisted and taped.

 

To add, I'd done the vertical chace to repair PROPERLY.

 

 

Is that plastic cable protection in the plaster?

 

I've only ever seen steel which is quiet resistant to masonary drill bits in case someone attempts to hang a shelf / cupboard / TV stand etc... in the wrong place.

[Ditto]

This is how a "professional" electrician wired Mrs_C's kitchen...

 

[ATTACH=CONFIG]72185[/ATTACH]

 

Spot the point where the screw hit the cooker circuit. And was then twisted and taped.

 

To add, I'd done the vertical chace to repair PROPERLY.

Flipping 'eck. A good few near misses too by the looks of it!

[Chris_Cook]

Cable Zones if its helpful to any one:

 

 

Probably useful if you screw stuff into the wall at work.