Intermittent shock at kitchen sink

[vbyrne]

I was called to a job Friday past,the lady of the house and her children are getting shock's from the kitchen sink. First thing I tested was the sink live, no normal. I then tested the earth which is TT and got a reading of 97 ohms I then tested the 10mm earth going to the water stopcock no problems there either. I then tested the three trips that are in the DB 3
30 Ma trips and all disconnecting with in the times . Any body any ideas??
cheers

 

[Geordie Spark]

Why? We live near a main road into the centre of a fairly large town and we're on a TT

Aye but ... ye knaa - It's Shields man. Yer lucky t hev leccy at all nivvor mind an earth forrit!!

 

[vbyrne]

Can you elaborate how the DB is configured. From what you have written, I am thinking is this three separate RCDs, or RCBOs in the DB? I presume all circuits are on an RCD, and these are modern RCDs and not some old Voltage Operated device?

it's a three din rail DB WITH a RCD on each rail controlling b type mcb's the house was rewired 2 yrs ago. A good job was done on it looked at the overall job just to see what I was really looking at but it is sound

 

[vbyrne]

is the sink bonded?

the flow of water could be generating static in the sink etx

the pipes are cross bonded at sink but there is no wire running to the sink so that's what I'll do on Monday May be that'll cure it

 

[davesparks]

That won't cure it! It will either mask the problem a bit or it'll cause a nice bang to help you find the real cause of this. Or it might do nothing at all if they are metal pipes connected to metal taps on a metal sink, a bit of copper won't change the continuity there much.

If this install is only 2 years old then what's with the cross bonding? It's not something you see going in under sinks much these days!

 

[Pete999]

3 DIN rails each controlling cbs what sort of board is it?

 

[dellboy78]

I has something similar once. Turned out that the kitchen ring had broken cpc in 2 places, the washing machine was running in the section that wasn't earthed and had a small earth leakage fault on it. The sink, being bonded was providing a fault path when ever the lady was emptying the machine with her arm resting on the sink, or was in contact with the sink and any other metal appliance/socket in the area. I would test the kitchen circuits if you haven't all ready just to be sure the fault isn't elsewhere.

 

[vbyrne]

3 DIN rails each controlling cbs what sort of board is it?

its a south of Ireland board typical DB down there

 

[vbyrne]

I has something similar once. Turned out that the kitchen ring had broken cpc in 2 places, the washing machine was running in the section that wasn't earthed and had a small earth leakage fault on it. The sink, being bonded was providing a fault path when ever the lady was emptying the machine with her arm resting on the sink, or was in contact with the sink and any other metal appliance/socket in the area. I would test the kitchen circuits if you haven't all ready just to be sure the fault isn't elsewhere.

i will do that,cheers.

 

[vbyrne]

That won't cure it! It will either mask the problem a bit or it'll cause a nice bang to help you find the real cause of this. Or it might do nothing at all if they are metal pipes connected to metal taps on a metal sink, a bit of copper won't change the continuity there much.

If this install is only 2 years old then what's with the cross bonding? It's not something you see going in under sinks much these days!

i think the bonding was not touched during the rewire,if I was rewiring and there was earth bonding I would not pull it out, would you????

 

[dingledong]

I don't think I would but then again

 

[Farmelectrics]

recomend an eicr to be carried out any problems then youll find it and earn a few pennys aswell

 

[driverman]

It could also be something like Central Heating coming on via timer with an earth fault............Has happened before many years ago with dire consequences.