Main protective bonding conductors

[MajorOak]

I am not sure paths back through a shower are very common, as very few modern electric showers have many metal parts inside and mixer showers, especially power showers, are often fed at some point by short flexible lengths of pipe for connection to pumps. Most of these I have seen tend to be some sort of composite material not metal. Often plastic push fit.Doc H.

Immersion heater??

 

[ADS]

I don't know why so many people have trouble grasping this!

'Bonding' reduces differing potentials between mutually accessible metal parts.

It reduces the 'touch voltages' between two parts.

'Earthing' reduces the duration of a dangerous voltage on a metal part.

If the water pipe feeds a shower or a boiler etc, then the metal work it connects to within the shower or boiler is earthed if you follow that earth back to the MET it then connects to earth electrode at the incoming source if it's a TT or further up stream if it's a PME system or at the sub for a TN-S so the water pipe is introducing an earth potential around the building, be it indirectly.

The pipework is not introducing anything, anywhere.

If it's connected to the MET, then, (give or take), it will be at the same potential as the MET.

Boiler pipework is 'earthed' because the metalwork and pipework of a boiler are considered to be 'exposed conductive parts' - i.e. they could become live under fault conditions.

Nothing to do with bonding.

These earthed pipes/metalwork of the boiler will help clear the fault by tripping the RCD/MCB.

They may raise in potential whilst the clearing of the fault occurs - but that doesn't present a huge risk, as there aren't any 'un-bonded' 'extraneous conductive parts' to touch.

But they are not plastic are they? You've told us the internal pipework is copper (which it ALWAYS will be for a gas pipe, gas regs) - ergo the [wiring and gas] regs require MPB. What the supply pipe is made of is irrelevant in this situation.

This is just completely untrue.

As my previous post suggested - Do you bond all things metal in the building?

You might as well, if you believe metal pipework connected to plastic incommers requires it.

PC, I think the one way to solve this myth would be if you could quote a regulation and/or definition that tells us to 'bond' a plastic incomming 'service' pipe.

 

[steptoe]

you dont do anything to the incoming service, its not yours to touch,

same as the incoming supply isnt yours either,

its the bit on the consumers side of the stoptap/meter that you are concerned with.

is that metal or plastic?

if its metal it gets bonded,!

simple as,

and if you really need me to find you a reg to back that up then you really should try shelf stacking at aldi or something, cos you deffo shouldnt be allowed anywhere near electricity with that kind of nonsense understanding.

headbang

 

[Andy™]

you dont do anything to the incoming service, its not yours to touch,same as the incoming supply isnt yours either,

its the bit on the consumers side of the stoptap/meter that you are concerned with.

is that metal or plastic?

if its metal it gets bonded,!

simple as,

and if you really need me to find you a reg to back that up then you really should try shelf stacking at aldi or something, cos you deffo shouldnt be allowed anywhere near electricity with that kind of nonsense understanding.

headbang

actually, if it comes in as metallic and then to plastic, the supply is most likely extraneous so supply side must be bonded. if it comes in as plastic and then everything inside copper, then it may not need bonded, and i have done a few jobs where i didnt bond water. but i usually do

 

[steptoe]

[quote name='Andy

 

[PC Electrics]

OSG, section 4.4, page 29

In 411.3.1.2 the list of 5 items shall be connected to MET along with any other ECPs. The list of 5 is quite specific - they need bonding (if metal).

 

[ADS]

OSG, section 4.4, page 29

OSG, section 4.4, page 29

There is no requirement to main bond an incomming service where the incomming service pipe and the pipework within the installation are both of plastic. Where there is a plastic incomming service and a metal installation within the premises, main bonding is recommended unless it has been confirmed that any metal pipework within the building is not introducing earth potential.

So, like I said in an earlier post, if it's 'extraneous', you bond it - if it isn't, you don't............... I don't see the argument.

Oh, and Steptoe - notice they talk about 'incomming service'.

In 411.3.1.2 the list of 5 items shall be connected to MET along with any other ECPs. The list of 5 is quite specific - they need bonding (if metal).

NOT -If metal..........if EXTRANEOUS

411.3.1.2

In each installation main protective bonding conductors complying with Chapter 54 shall connect to the main earthing terminal extraneous conductive parts including the following:

(i) Water installation pipes

(ii) Gas installation pipes

Like I said, if they are extraneous!

My Blue

you dont do anything to the incoming service, its not yours to touch,same as the incoming supply isnt yours either,

its the bit on the consumers side of the stoptap/meter that you are concerned with.

is that metal or plastic?

if its metal it gets bonded,!

simple as,

and if you really need me to find you a reg to back that up then you really should try shelf stacking at aldi or something, cos you deffo shouldnt be allowed anywhere near electricity with that kind of nonsense understanding.

YES, PLEASEopcorn

 

[steptoe]

the OSG is not the regs,

I dont work to the OSG,

I dont know any electrician that does,

I work to the relevant regulations, and statutory law,

and like I said, the oneous is on you to PROVE it doesnt need bonded.

 

[ADS]

the OSG is not the regs,I dont work to the OSG,

I dont know any electrician that does,

I work to the relevant regulations, and statutory law,

and like I said, the oneous is on you to PROVE it doesnt need bonded.

You don't have to 'prove' anything!

Who are you going to prove it to?

You check if it's extraneous - if it is, you bond it, if it's not, you don't.

 

[steptoe]

the dead persons lawyer?

I suppose you dont have to prove your wiring is safe to use then?

and I thought it was the law,

silly me.

that has to be one of the stupidest things on here,

oh course you have to prove it,

you have to prove almost everything you do,

thats why we have certs to fill in,

unless you were a stetson that is.

 

[Andy™]

since when,?the supply side is ABSOLUTELY NOTHING to do with the consumer,

I suppose a leak in the road is the consumers responsibility too?

415.2.1 - (short version) - supplementary bonding to extraneous conductive parts.

extraneous conductive part: conductive part liable to introduce potential....

so, if you have a metallic service pipe going to plastic inside, then the metallic service pipe may be extraneous, and may need bonded. which means you may have to bond the incoming side.

---------- Post Auto-Merged at 21:57 ---------- Previous post was made at 21:54 ----------

and just to add to it.... if someone was to hammer in an earth rod, which you could not remove, then you would have to earth it (since its extraneous).... even if its TNCS. imagine that. an earth rod on TNCS.

 

[Andy™]

fortunately not

 

[Sidewinder]

Now I'm confused again, what's wrong with an earth rod on TN-C-S?...

 

[steptoe]

I think you will find that in order for it to be extraneous it would have to be connected to something inside the EZ.

oh, and in order for TNCS to be a proper PME system it would require an earth rod to be installed,

this is why in the simplified earthing thread I omitted the explanation about localised rodding of TNCS systems as it actually requires an understanding of earthing.

seems you are one of the people that dont fully understand the principles of what earthing does or how it works and its influence on the equipotential zone.

 

[Sidewinder]

As I have said before, there is actually a reg that requires an earth rod to be installed under certain circumstances when the install is supplied by a TN-C-S +/ or PME supply.

 

[Andy™]

I think you will find that in order for it to be extraneous it would have to be connected to something inside the EZ.

not always.

imagine you have a TNS supply with incoming cable at front of house. you have a water service at the back of the house with a metallic pipe, but plastic inside so you neglect to bond it. said water pipe is common to the street. next door has TT, with rod and gas/water bonded, and has a fault that raises their earth voltage to dangerously high. now since its a common metallic pipe between you and next door,i can guarantee you that the pipe you didnt bond will now be at a different voltage to the rest of the installation.

so, said pipe is extraneous and should be bonded. simple.

also, it works the other way. if you have a fault in the installation which raises the voltage, then there will be a difference between installation earth & extraneous part

 

[ADS]

I think you will find that in order for it to be extraneous it would have to be connected to something inside the EZ.

What kind of statement is that from a qualified electrician???

Extraneous conductive part A conductive part liable to introduce a potential, generally earth potential, and not being part of the electrical installation.

seems you are one of the people that dont fully understand the principles of what earthing does or how it works and its influence on the equipotential zone.

And it seems you are one of the people that don't fully understand the principles of what bonding does.

 

[steptoe]

[quote name='Andy

 

[ADS]

I knew I should have earthed the metal railings at the bottom of my back yard,! doh.!

Now are you sure you meant 'earth' them - or are you thinking they require 'bonding'. :^O

I'm having second thoughts myself now - metal pipe........in the building........within the 'equipotential zone'..........hmmm - I've got a 4 foot length of copper pipe lying in the hall, better go and 'bond' it........ oh no, hang on......it's NOT EXTRANEOUS!!!!

Anyway, back on topic......

So if you where wiring these properties would you install main protective bonding conductors to these services concidering they are both plastic!? Cheers

GS

GS,

Take a resistance measurement between the offending pipe and the MET.

If your reading is bigger than 22 K ohms, then you can consider it not extraneous, and not bother bonding.

This would be the proof that Steptoe requires.

 

[steptoe]

Now are you sure you meant 'earth' them - or are you thinking they require 'bonding'. :^O main earth bond or supplementary earth bonding?

I'm having second thoughts myself now - metal pipe........in the building........within the 'equipotential zone'..........hmmm - I've got a 4 foot length of copper pipe lying in the hall, better go and 'bond' it........ oh no, hang on......it's NOT EXTRANEOUS!!!!

Anyway, back on topic......

GS,

Take a resistance measurement between the offending pipe and the MET.

If your reading is bigger than 22 K ohms, then you can consider it not extraneous, and not bother bonding.

This would be the proof that Steptoe BS7671 requires.

in red

and can you also take into account that this pipework is very unlikely for the duration of the life of the installation to fall under the 22K so as will not require bonding in the future?

remember, you are putting your name to this that it should be safe and meet the regulations in force at this time until XXdate ,

this also means, IMO, that should that pipe be 15K in a years time it no longer complies with the regulations in place when the installation was tested,

I know it is like an MOT,

but a lot harder for you to prove this pipe actually complied, after all, nothing has changed, apart from the new outside tap, and that is nothing to do with electrics so how could burying a copper pipe under the patio to a standpipe possibly change the safety of the electrical installation.?