A story of bonding

[SimpleSimon]

Thought I'd share this with you today.
Went to a customers house who after coming back from his holidays had a leak in the bathroom and spread to the airing cupboard.
On having this leak it's made all the water pipes in the property live. So customer disconnected immersion circuit at the fuse and I come round.
IR the circuit, get poor reading of 0.43 N-E. Looks like water damage in the wall. But why didn't the fuse blow when he got a shock? No RCD, support bonding non-existent in bathroom but present in airing cupboard.
Go downstairs to main bonding conductor under sink, do a continuity between disconnected bonding conductor at both ends of the run and find that the conductor which can be no more than a 1.5m has a reading of 1.05ohms. Hmm its seems the bonding was so old and corroded under the sink it wasn't allowing enough fault current to flow to blow the fuse. So always check the 0.05ohms reading regardless of length because you never know.
Can't go behind the walls just yet as it housing association.

 

[malcolmsanford]

So gents let's see if anyone can help me on this one. Same property, have yet to go back and do any work. When I left the first day I left the guy with an alternative. His two immersions where on plug top plugged into immersion circuit. I told him when I rewire the circuit these will be hard-wired in. So I put them on an extension and plugged it into the main ring so he can have hot water. Got a call couple days later saying he's tried it for 10 hours, no hot water.
Plumber got sent today to change immersions. Same thing, changes them over and starts working (can hear it in the cillender) them stops. Plumbers on the phone to me, continuity of 20 ohms on the immersions, power to it still not working with two new elements. Any idea lads? I'm sure it's got something to do with it still flowing to earth but can't figure of the pieces, any help?
Many thanks

Thank you Sparky 3366 spot on ................try the extension lead plug.

 

[Knobhead]

Si, their not on E7 are they? It’s just the fact you mentioned 2 immersion heaters that made me think.

 

[SimpleSimon]

Yes Tony E7. My other theory is that the leak has damaged the ring even though there are no socket outlets close to the ring so I'm unable to confirm if the ring is even there.
It's a strange strange one. My other theory is plug it on the downstairs ring and see what happens than.

 

[SimpleSimon]

Ok mystery over.went last night to check it out and the extension lead he was using was one he took from work that serviced a bank of computers. Naturally it had blown the 5a fuse that protects the outlet. Case closed for now.

 

[ezzzekiel]

Hmm its seems the bonding was so old and corroded under the sink it wasn't allowing enough fault current to flow to blow the fuse.

isnt the bonding there too make sure all bonded pipework rises to the same potential under fault conditions and earthing to disconnect the fault

 

[SimpleSimon]

Yep. And it wasn't