Earthing CU

[hard-work]

New CU in an all electric flat, no gas pipes. Plastic water mains. CU has double RCD all circuits RCD protected. Only earth cable is the incoming earth cable. AIUI, no need to have any earth cable from the CU to any pipe as nothing to clamp onto. Correct?

 

[JohnW2]

New CU in an all electric flat, no gas pipes. Plastic water mains. CU has double RCD all circuits RCD protected. Only earth cable is the incoming earth cable. AIUI, no need to have any earth cable from the CU to any pipe as nothing to clamp onto. Correct?

You're presumably talking abound bonding (not 'earthing') cables. If no metal pipes (or other metal things) enter the premises from outside then, yes, there is obviously nothing that could be bonded.

Kind Regards, John

 

[hard-work]

Thanks. No bonding is required, such as earth cables linking copper water pipes around a cylinder?

 

[JohnW2]

Thanks. No bonding is required, such as earth cables linking copper water pipes around a cylinder?

That is never required, other than in the minds of plumbers. There are just a few situations in which 'supplementary bonding' is still required in bathrooms, but those situations are becoming increasingly rare.

Kind Regards, John

 

[JohnD]

many plumbers like to bond the pipes around the boiler (sometimes a pipe clamp jig is provided which does that). This may include pipes to the main incoming services, and to the cylinder which may have a thermostat and an immersion heater. The manufacturer's instructions may specift it, I don't know.

It's hardly necessary when all the pipes are connected to the same metal boiler, but it was pointed out to me that when the boiler is being installed or removed, the installer is faced with water and gas pipes which, in the event of fault, may have a PD, and he may be touching one while spannering another, so the bonding is a useful safety feature for him.

 

[JohnW2]

It's hardly necessary when all the pipes are connected to the same metal boiler, but it was pointed out to me that when the boiler is being installed or removed, the installer is faced with water and gas pipes which, in the event of fault, may have a PD, and he may be touching one while spannering another, so the bonding is a useful safety feature for him.

I suppose it depends upon how 'risk averse' one is, but you are talking about what must surely be an extremely improbable scenario, probably requiring more than one fault - it's difficult to see how any of the pipes could "have a PD", since anything electrical connected to the pipework would usually also involve a CPC being connected to the pipework.

As is often pointed out, the downside of any 'unnecessary' bonding is that it nearly always will result in 'unnecessary earthing' (if the part wasn't earthed, anyway) - and increasing the amount of earthed metal around increases the hazard (for plumbers and others) if they happen to touch that metal whilst also touching something 'live'.

Kind Regards, John

 

[JohnD]

there's no accounting for plumbers.

 

[JohnW2]

.... But there's no accounting for plumbers.

I wouldn't personally be too critical of plumbers in this particular respect. Decades ago when I first came across 'cross-bonding' of pipes around boilers etc. and in airing cupboards etc., it seemed 'very reasonable' to me, and I didn't think enough to question it.

Kind Regards, John