Discuss Water bond, Insulated Section. in the Electrical Forum area at ElectriciansForums.net

ChrisElectrical88

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Afternoon Gents,

Came across a nice scenario today. Water pipe comes from the street, into the kitchen through a concrete floor. 100mm of copper behind a kickboard where it comes through the concrete 300ish mm of Plastic Pipe, 100mm of copper then stop tap. 90 percent of the installation is copper. IR from disconnected MET to first 100mm of pipe is 967 Ohms, After the plastic pipe its 28K Ohms, obviously over the 23K Ohms recommended.
First time i have come across an Insulated Section (Thats not the big blue water main.)

Would you bond and why?
 
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Midwest

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Not sure of your description exactly, but does the installation have additional protection to all circuits?
 

ChrisElectrical88

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Basically there is a plastic piece of pipe 300mm ish long 100mm away from the water pipes point of entry, under a kickboard so inaccessible.
Reading after the plastic pipe to the met is more than the 23 K Ohms revommended.

Im just making sure i havent missed a point in 411.3.1.2 which discribes this exact scenario.

Upstairs lights, alarm and dporbell have no additional protection
 
D

Deleted member 9648

Whats it got to do with additional protection to all circuits?
 
D

Deleted member 9648

I was referring to Midwests post, cant see the relevance of RCD protection to a main bonding query.
 
My understanding of that Regulation is that the incoming service pipe is plastic, yours is metal so to me that requires bonding.
 

ChrisElectrical88

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My understanding of that Regulation is that the incoming service pipe is plastic, yours is metal so to me that requires bonding.
Metallic pipes entering the building having an insulating section at their point of entry need not be connected to the protective equipotential bonding

So it actually states in the reg it concerns metal services entering the building
 
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Deleted member 9648

My understanding of that Regulation is that the incoming service pipe is plastic, yours is metal so to me that requires bonding.
The regulation states "Metallic pipes entering the building having an insulating section at the point of entry...…."
 
D

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I'd regard an insulating section 100mm from the point of entry as at the point of entry. There is 100mm of extraneous CP.The chances of simultaneous contact with a conductive part are about zilch
 

ChrisElectrical88

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I'd regard an insulating section 100mm from the point of entry as at the point of entry. There is 100mm of extraneous CP.The chances of simultaneous contact with a conductive part are about zilch
Its under the kitchen units aswell, you would have to get under the units reach for the pipe and stick your big toe on the dishwaher at the exact point a fault occurs.
 

Baddegg

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I’d say doesn’t need bonding but I’d make a note and include the test results......just in case wet pants replaces that section in the future for any reason....
 

mattg4321

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I'd say it possibly doesn't need bonding because it could be viewed as not being accessible. Bit of a grey area though. I'd probably just bond it if it were easy. Doubt it is though!
 

SparkyChick

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This is what I wrote on a certificate when I decided not to bond a water pipe.

"No Bonding To Water

Using guidance in section 6 of IET Guidance Note 8 (Earthing and Bonding), the requirement for bonding to the incoming water supply was checked and it was decided a bonding connection was not needed.

Using Rcp>(U0/Ib)-ZT with U0 = 230v, Ib = 10mA, ZT = 1000ohm which gives a limit of 22kohm, the continuity between the pipework (following the switch from plastic) to the MET was checked and found to be 42kohm."
 

Midwest

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Whats it got to do with additional protection to all circuits?
I was thinking of the point of establishing whether the pipework was extraneous or not. Haven't GN8 to hand re SparkyChicks #, but I've used 415.2.2 equation (in the past) for the lowest resistance where a piece of metal does not require bonding.
 

ChrisElectrical88

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Thats all for the input. Just found out that the entry point has been dry lined streight over, so it can even be touched anymore. The first point of contact for the water is now the stop cock, which is after the insulated section.
 

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