your comments pls

[Jonnyboy 68]

your comments pls boys

been working with another spark (Dangerous I know !!) and as always we have a couple of differences of opinion...

My understanding is when a 17th Edition CU has been installed, all circuits now RCD protected, as long the main bonding (Gas, Water) is in place and verified, no other bonding is necessary p166 701.415.2 BRB ???

Also, interestingly, would you recommend any existing supplementary bonding be removed or leave it in place ?

Another old chestnut.... the main water supply to the property is in plastic and then copper throughout the property... I've been bonding at the first available bit of copper after the stopcock... I thought i read a thread on here some time ago about the possibility of conductivity of the water within the pipe ??? I reckon ther's still a chance of a potential existing within the property so better to be safe eh ..My mate reckons if plastic incoming then no need to bond...

your views pls boys .. there's beers on this Guinness

 

[ianmacd]

Needs to be confirmed by testing the resistance between your MET and the pipes and if its under 22kohm (from mem) then it should be bonded.

 

[jimleen]

NICEIC have decided that anything under 6,667 ohms is extraneous.

 

[ianmacd]

NICEIC have decided that anything under 6,667 ohms is extraneous.

Thats nice of them to do that.

 

[Badger]

:Applaud

 

[PC Electrics]

your comments pls boysbeen working with another spark (Dangerous I know !!) and as always we have a couple of differences of opinion...

My understanding is when a 17th Edition CU has been installed, all circuits now RCD protected, as long the main bonding (Gas, Water) is in place and verified, no other bonding is necessary p166 701.415.2 BRB ???

correct

Also, interestingly, would you recommend any existing supplementary bonding be removed or leave it in place ?

leave unless removing for aesthetic or other reasons

Another old chestnut.... the main water supply to the property is in plastic and then copper throughout the property... I've been bonding at the first available bit of copper after the stopcock... correct .. I thought i read a thread on here some time ago about the possibility of conductivity of the water within the pipe ??? I reckon ther's still a chance of a potential existing within the property so better to be safe eh ..My mate reckons if plastic incoming then no need to bond... incorrect, see your OSG section 4.4

your views pls boys .. there's beers on this Guinness

my responses in blue

 

[a1spark]

NICEIC have decided that anything under 6,667 ohms is extraneous.

Hi jim.

Would that figure not be 1667 ? I ask this as this is the max R value to ensure the 50 volt touch threshold is not exeeded when 30ma rcd protection is installed.which would be the case in the OPs example. Any value between this and the value 22000 ,would still require Supplementary bonding and any value exeeding 22000 would be classed as not extraneous and thus supp bonding not required.

Johnnyboy , you ommitted to mention that disconnection times must also be met for Supp bonding ommision.I would leave any existing bonding in place if possible ...whats the -In Service- failure rate of RCDs ? 3% or 4% I think ,so leave it in as belt and braces job in my opinion.

Best way to find out if internal copper pipework requires Main Bonding where the incoming service pipework is plastic is to measure back to the MET with your wander lead and base your descision on your findings.

 

[ADS]

No, Jim is correct - they have quoted 6667 ohms in one of their newsletters.

They use the same equation as GN8 to get to this figure, but they use a 30mA current, as opposed to 10mA used in GN8 (what GN8 terms the let-go threshold).

The 10mA will give you 22 Kohm (as Ian suggested), and this is the figure I'd stick with, personally.

GN8 actually suggests that you should consider variations in resistance and possibly go with lower than 10 mA, so I don't know what the NICEIC are on about.

I'd rather be cautious and bond anything under 22000 ohms than go with the NICEIC and only bond if under 6667 ohms.

Once again, they don't make the rules.

 

[septiclecky]

NICEIC have decided that anything under 6,667 ohms is extraneous.

But they don't write the regs the IET does although they try to make out to Joe Public they dobad day explodebad day explodebad day explode

 

[Jonnyboy 68]

Many Thanks All ...

Lets see what we disagree about tomorrow ....

:Salute