CU Change - No main earthing on water main. Polypipe incomer

[telectrix]

also depends on how fast you crank the handle on the megger

 

[Hawk81]

Well in my humble opinion to bring it back to the main question there is no need to bond the water pipe. as it is plastic then it is not needed. we bond as to stop a potential earth difference not to make sure that the rest of the copper pipes is earthed. surely any assesor will understand this or he should not be in his job.

 

[pushrod]

Not sure at all about this but isn't there a resistance value between the pipework and earth which shows whether or not something is an extraneous conductor or not and so if it will need bonding -> 20 KΩ and you don't need to bond??? or am i thinking of something completely different

 

[antimatter]

Section 4.4 OSG

The is no requirement to main bond an incoming service where the incoming service pipe and the pipework within the installation are both of plastic. Where there is a plastic incoming service and a metal installation within the premises, main bonding is recommended unless it has been conformed that any metal pipework within the building is not introducing earth potential. All bonding connections are to the consumers side of any meter, main stopcock or insulatinf insert.

 

[pushrod]

Section 4.4 OSG

unless it has been conformed that any metal pipework within the building is not introducing earth potential.

so how do you confirm that - is it what i said above? (on reflection is the figure 22 kΩ?)

 

[antimatter]

Simple answer - f$%k knows, anyone care to interpret for us?

 

[robsparky1975]

According to the on site guide,when polypipe incomer no main earth bond required as already pointed out,one of the first things i do when looking to upgrade to a new consumer unit is to check the sizing and connection of all earthing conductors,saves any problems later,anyway,one way of introducing earth potential might be an outside water supply in copper etc.mind you they say u dont need it on polypipe but on new builds i put it in just incase they change the regs in years to come and say its needed.

 

[Johno]

As already said, if it is a plastic pipe then no need to main earth bond, but you still need to make sure that the resistance is low between pipes and class II equipment in the bathroom (sorry I have forgot the formula) to rule out supplementary bonding.

 

[Johno]

If it were me having my assessment I would bond it.

 

[telectrix]

Bond it. they can't fail you for overdoing it, but they can if the assessor thinks it should be done and it ain't

 

[pushrod]

As already said, if it is a plastic pipe then no need to main earth bond, but you still need to make sure that the resistance is low between pipes and class II equipment in the bathroom (sorry I have forgot the formula) to rule out supplementary bonding.

touch voltage of 50V and current thru rcd of 30mA (0.03A) so R = V/I = 230/0.03 =1667ohms
if R is < 1667 Ω no supp bonding needed

 

[Des 56]

Aside from the main topic of whether main bonding is needed or not

If you decide that it is not going to be installed
You must carry out supplementary bonding in the bathroom because you can not meet the conditions for ommision
It has to be a building with protective equipotential bonding to do so

There seems to be a lot of opinion saying not required,my own understanding is that a full cooper system would require the main bond ,whereas if the supply and major parts of the plumbing are plastic then omit

 

[Spudnik]

Again, i agree with Des.

However, if im doing a rewire, then ill always throw in a bond, even if not needed due to poly incommer.

Wasteful? ... Maybe.

 

[nickblake]

Had a house that had no bond to water and a radial circuit with 4 sockets on it a cold water feed to a pump due to low pressure on the icoming main plugged into a socket on a radial plug a socket tester in all ok Zs the socket high readings , socket tester in reading unplug the pump earth fault the house was all plumbed in plastic but was finding a small earth through the water so there is still the potential from the water service be it only small its possible if its copper , but asringer has been said contact your trade body for advise,personally i would install the bond, always do

 

[Deleted member 9648]

IMO a main bond should be provided on the first available section of copper...even if the service is not introducing an earth potential at the time of the install conditions may change......CYA.