Will bonding cause an MCB to operate?

[ebee]

Even with ideal insulators, in an AC system, a sufficiently large system of interconnected metal is effectively an earth reference, even if there is no conductive path to earth.

Agreed, not just a conductive path (however small) but also an inductive path or a capacitive path might give us some reference to "Earth" or some other potential.

We sometimes refer to "Earth" in the humble motor car but usually the sit on tyres full of air so no real earth about and when some say earth they really mean chasis which is not the same thing.
Some even sometimes add little insulating strips to link chasis to road earth by some bizzare logic but unless there is some conductivity then how can that work?

 

[JohnW2]

Even with ideal insulators, in an AC system, a sufficiently large system of interconnected metal is effectively an earth reference, even if there is no conductive path to earth.

Whilst that is literally true, qualitatively, I doubt whether (m)any domestic premises have "a sufficiently large system of interconnected [and touchable] metal" for what you say to be particularly 'significant'.

In any event, in the context ebee raised the issue, isn't it earth-refencing of the supply (i.e. at the transformer) that primarily matters? ... and, in the absence of a direct (conductor) connection to earth, I can't see why any capacitive or inductive coupling should preferentially be to one of the 'outputs' of the transformer?

 

[mikehammer69]

Agreed, not just a conductive path (however small) but also an inductive path or a capacitive path might give us some reference to "Earth" or some other potential.

We sometimes refer to "Earth" in the humble motor car but usually the sit on tyres full of air so no real earth about and when some say earth they really mean chasis which is not the same thing.
Some even sometimes add little insulating strips to link chasis to road earth by some bizzare logic but unless there is some conductivity then how can that work?

I had assumed the earthing straps on cars had a metal core

Haven’t checked it

There’s a way of avoiding static when exiting a car

You exit by holding onto car metallic before feet touch ground

 

[ebee]

Wont that ensure that you become "fully charged" before stepping onto the ground (Earth) unless those rubber strips are replaced with dangling metal chains?

PS - I remember years ago, when I was a lad, some were pretty much just bog standard rubber hence little, if any, conductivity and folks used to swear by them - placebo?

It is a "little while" since I was at school though!

 

[mikehammer69]

Wont that ensure that you become "fully charged" before stepping onto the ground (Earth) unless those rubber strips are replaced with dangling metal chains?

Are you replying to my point about avoiding static shock ?

That method definitely works

I don't know very much otherwise without researching

 

[ericmark]

Agreed, not just a conductive path (however small) but also an inductive path or a capacitive path might give us some reference to "Earth" or some other potential.

We sometimes refer to "Earth" in the humble motor car but usually the sit on tyres full of air so no real earth about and when some say earth they really mean chasis which is not the same thing.
Some even sometimes add little insulating strips to link chasis to road earth by some bizzare logic but unless there is some conductivity then how can that work?

Seem to remember there is graphite in the material used to make tyres so they will allow static to return to earth and stop the static build up, same with wellingtons, they will not isolate you from the ground. When the graphite was put in the tyres, there was no need any longer to have graphite impregnated earth strips or chains except for making money by selling them.

The earthing stuff used to work with electronics also often graphite impregnated.

The so-called earth return with motor vehicles saved using a return wire, but even when that system was not used, as with petrol tankers etc, often the carbon from the brushes in the starter motor would still mean the negative went to earth.

 

[mikehammer69]

..

 

[ebee]

Are you replying to my point about avoiding static shock ?

That method definitely works

I don't know very much otherwise without researching

Yes Mike , I know what it used to be - non conductive pretty much, but that was a good few years back now so the graphic/granules idea metioned might well have altered that, I think that many if not all of the original ones were questionable but later ones may well have reduced the problems significantly but it would not completely surprise me if there are still a few on such as fleabay are nothing more than a strip of insulating rubber etc too, if anone has some and they can meter them out for comparison we might get some answers.