MEB Bonding to Incoming Gas Pipe

[horaceg]

In Line with Reg: 413-02-02 a Main Equipotential Bonding Conductor must be run to incoming services such as Water & Gas.
547-02-02 states this bond must be made within 600mm of Point of Entry to the building.

In TN-C-S Installations it has been noted that, occasionally, the voltage will rise on the Neutral/Earth Terminal above 0 volts.
This is not as much a problem as it may at first appear as the idea of the earth bonding is to ensure that there will be no potential DIFFERENCE between simultanious conductive parts within the installation thereby not presenting a shock hazard.

However, in the case of the incoming gas main, it is quite common for the pipe to run from an external meter for some distance outside the building before entering.
If the voltage did rise on the neutral/earth, this would be present on this external pipe and create a potential difference between the external pipe and ground.
This would be solved by installing an insulated section of gas pipe as it enters the building thereby effectively insulating the 'upstream pipe'.

Does anyone know if this IS a requirement and, if not, why not?

 

[gittish_bass]

ok, I don't believe that to insulate the gas pipe for this reason is a requirement, however equipotential bonding should protect the pipework from an electrical fault either inside or outside of a building, therefore electrial continuity in the pipework must be maintained at all times.

As for why not, well above ground external gas pipework should be bonded 'preferably' (but not necessarily) inside the building.

If a competent person deems this necessary to bond externally and it is mechanically sound and not subject to corrosion then 'just do it'.

Regards

 

[horaceg]

ok, I don't believe that to insulate the gas pipe for this reason is a requirement, however equipotential bonding should protect the pipework from an electrical fault either inside or outside of a building, therefore electrial continuity in the pipework must be maintained at all times.

As for why not, well above ground external gas pipework should be bonded 'preferably' (but not necessarily) inside the building.

If a competent person deems this necessary to bond externally and it is mechanically sound and not subject to corrosion the 'just do it'.

Regards

Thanks for the reply.

All you say is true but doesn't address the main issue.

In the event of a rise in voltage from the incoming Neutral/Earth in a TN-C-S installation, this voltage would be present OUTSIDE the building on the external pipe and present a Potential Difference with the general mass of earth. Anyone, say a small child, running around in the garden virually naked in the summer (I do it all the time but don't tell the neighbours!) may inadvertantly come into contact with this pipe and receive a shock.
Some years ago the old LEB required, in a PME installation, that outside taps be piped with an insulated section, isolating it from the internal pipework and also, I believe, there is still a requirement for external light fittings to be either All Insulated or out-of-reach.

It seems to me that this issue is being 'ducked' by the powers that be or that the 'ever-powerful' CORGI lobby have kept this out of the lime-light!

Cheers

HoraceG