Protective bonding

[EFLImpudence]

Oh sorry about the thread. I will move my post.

 

[EFLImpudence]

...

 

[EFLImpudence]

Given that one would only be interested in satisfying 701.415.2(vi) if RCD protection were present, 415.2.2 only requires that the measured resistance be less than about 1,666Ω - would you really consider two things to be 'effectively connected' if you measured, say, 1,500Ω between them?

I can only say, as you know, that that is the nominal value for a 30mA RCD, just as 1.666Ω is for a 6A B MCB.

 

[JohnW2]

I can only say, as you know, that that is the nominal value for a 30mA RCD, just as 1.666Ω is for a 6A B MCB.

I'm not sure that "nominal" is the most appropriate word. Those are the resistances which cause the respective devices to operate with a 'driving voltage' of 50V - and there would seem to be a fair bit of "abitrariness" in that

However, I was talking more in terms of electrical knowledge and common sense. If you were not familiar with the regulations etc. we've been discussing, if I told you that we needed to undertake a test to see if two things were (electrically) "effectively connected together", I doubt that you would suggest that finding a resistance of, say, 1,500Ω indicated an 'effective connection', would you? I would have said that in the vast majority of contexts, that figure would be far too high to represent a 'good (or 'effective') connection', wouldn't you agree?

Kind Regards, John

 

[studentspark]

Are you measuring the towel rail itself or the pipes to it?

Pipe work, It does have a pipe cover on it, but with a thin probe Im pretty sure Im touching copper. I find the chrome covering gives poor readings.
But I generally get a decent connection at the vent, and this was still poor

..and are there any exposed-c-ps in the bathroom?

No. switching is outside. Plastic LED bulk head light.
Im going back in so I think i will lift a board in the hallway outside, see what kind of readings I get on the pipework going into the bath room

Thanks

 

[JohnW2]

No. switching is outside. Plastic LED bulk head light. ... Im going back in so I think i will lift a board in the hallway outside, see what kind of readings I get on the pipework going into the bath room

What readings to you get from other extraneous-c-ps in the bathroom (e.g. hot & cold pipes and taps)? Is there a radiator in the room as well as the towel rail - if so, what about that?

Kind Regards, John

 

[JohnW2]

Is it a question of having 'proper SB' - or rather to meet the conditions of 701.415.2(vi) for omitting SB with RCDs this one item has to be effectively connected to the PEB (which, according to the note can be determined by the application of 415.2.2).

Another aspect of apparent silliness has occurred to me....

If one wishes to avoid the need for 'proper SB', and if all conditions for omitting it are satisfied other than (as in studentspark's case) one extraneous-c-p not satisfying 701.415.2(vi), then one can avoid the need for 'proper SB' by installing 'improper SB' ("plumber's bonding") which just joins the 'offending' extraneous-c-p to some other ('compliant') extraneous-c-p

Kind Regards, John