When are fly leads necessary?

[bernardgreen]

I doubt anyone has come to significant physical harm from touching a face plate screw that was Live,

But there might have been instances where psychological harm was a result of a tingle from a face plate screw that was Live,

It doesn't take much to create a phobia about the safety of electricity.

 

[JohnW2]

I doubt anyone has come to significant physical harm from touching a face plate screw that was Live, But there might have been instances where psychological harm was a result of a tingle from a face plate screw that was Live, It doesn't take much to create a phobia about the safety of electricity.

I don't think I am going to respond to that specifically, since the implications of that view/approach are so wide-ranging in relation to almost everything in life.

However, although I wrote ...

.... I do have to wonder whether anyone has ever (say in the last 50 years) come across, or heard of, a case in which anyone has come to significant harm (let alone died) as a result of a 'live' faceplate screw.

I might well have written ...

.... I do have to wonder whether anyone has ever (say in the last 50 years) come across, or heard of, a case in which anyone has suffered a significant electric shock as a result of a 'live' faceplate screw.

...or even ...

.... I do have to wonder whether anyone has ever (say in the last 50 years) come across, or heard of, a case in which anyone has suffered an electric shock as a result of a 'live' faceplate screw.

.... although the latter might, in the eyes of the 'victims', be confused by the fact that people may perceive that they have got 'shocks' or 'tingles' by touching earthed things which certainly are not live'.

What would be your view regarding those further things that I "wonder about"?
'
Kind Regards, John

 

[winston1]

I have in the past received static discharging from a face plate screw after walking over a dry carpet. Some people get paranoid when this happens.

 

[sparkwright]

I have in the past received static discharging from a face plate screw after walking over a dry carpet. Some people get paranoid when this happens.

Yes, I had the same issue, I put it down to a new thick nylon carpet.

 

[JohnW2]

I have in the past received static discharging from a face plate screw after walking over a dry carpet. Some people get paranoid when this happens.

Exactly - and similarly by touching any number of other earthed things, not just faceplate screws.

That's why I think my "wondering" about how many people have suffered "significant" electric shocks from faceplate screws is more useful that it would be without the "significant" (although, admittedly, one man's "not significant" might be another man's "significant" ).

Kind Regards, John

 

[bernardgreen]

The discharge of a static charge from body to earthed metal is ( normally ) of very short duration ( Wimshurst machines excluded ) where as the tingle / shock from a source of Live potential lasts for as long as the contact is made.

Most people can ( be persuaded to ) accept this explanation of the difference between ( relatively ) harmless static discharges and potentially harmful contact with items that are at Live potential.

 

[JohnW2]

The discharge of a static charge from body to earthed metal is ( normally ) of very short duration ( Wimshurst machines excluded ) where as the tingle / shock from a source of Live potential lasts for as long as the contact is made. Most people can ( be persuaded to ) accept this explanation of the difference between ( relatively ) harmless static discharges and potentially harmful contact with items that are at Live potential.

All true but, as you imply, some (including a good few who come here to voice their concerns) need 'persuading', having initially been very concerned about what they perceived as 'electric shocks'.

For that reason, I think it better to leave my 'wondering' to whether anyone has ever experienced a significant electric shock as a result of a 'live' faceplate screw. Have you ever heard of that happening and, if not, do you think it 'likely' that it has ever happened?

Kind Regards, John

 

[bernardgreen]

Many years ago I had a tingle from an un-insulted screw driver when using it to tighten a face plate screw. I told the house owner they needed to get the electrics checked out as for all I knew the CPC may have been Live due to faults/errors in the wiring.

Have I heard of significant electric shock / harm from contact with a Live face plate screw ? No

Do I think it likely ?, No

but at the same time I do not believe it could never happen.

 

[JohnW2]

Many years ago I had a tingle from an un-insulted screw driver when using it to tighten a face plate screw. I told the house owner they needed to get the electrics checked out as for all I knew the CPC may have been Live due to faults/errors in the wiring.

That's fair enough - I dare say most of us could tell similar stories.

Have I heard of significant electric shock / harm from contact with a Live face plate screw ? No Do I think it likely ?, No

You will understand that my answers would be the same, although I might qualify the latter to indicate that I personally thought it was 'very'or 'extremely' unlikely.

... but at the same time I do not believe it could never happen.

Of course not. There are remarkably few things about life (other than 'living for ever') which could 'never happen'. People get struck by lightning, and I suspect that at least some have, over the centuries/millennia, been struck by meteorites - and some unlucky people certainly suffer from 'incredibly rare diseases' and/or incredibly improbable 'fluke accidents'.

However, this is where one needs to take a sensible view of probabilities (i.e. the magnitude of 'risk') since, otherwise. life would become impossible.

Kind Regards, John

 

[333rocky333]

I'm not quite sure what you are saying,unless it's just 'a statement of the obvious'.

Kind Regards, John

The Op was asking when a flylead was necessary, so I was referring to 543.2.7

 

[JohnW2]

I'm not quite sure what you are saying, unless it's just 'a statement of the obvious'.

The Op was asking when a flylead was necessary, so I was referring to 543.2.7

Fair enough, but I would personally say that 543.2.7 is also "a statement of the obvious"!

If an accessory (such as a socket, FCU or metal switch) has an 'earth terminal' (because it needs to be 'earthed'), and if the only 'earth' available is that connected to the backbox by conduit/SWA armour etc., then it is glaringly obvious that the accessory's earth terminal has to be connected to the box with a protective conductor (aka 'flylead'), isn't it?

Kind Regards, John

 

[plugwash]

it is glaringly obvious that the accessory's earth terminal has to be connected to the box with a protective conductor (aka 'flylead'), isn't it?

No, I don't think it's "glaringly obvious".

Its "glaringly obvious" that the accessory needs to be earthed, but it's an explicit decision on that part of those writing the regs that it is NOT ok to rely on the fixing screws and earth strap or metal plate of the accessory for that purpose.

There is a clear asymmetry here which I believe correctly reflects the different risk profiles of the accessory and the back box.

 

[bernardgreen]

then it is glaringly obvious

Many incidents have happened because what was "glaringly obvious" to many people was not "glaringly obvious" to everyone,

 

[JohnW2]

No, I don't think it's "glaringly obvious". .... Its "glaringly obvious" that the accessory needs to be earthed, but it's an explicit decision on that part of those writing the regs that it is NOT ok to rely on the fixing screws and earth strap or metal plate of the accessory for that purpose.

Maybe you're right, and I was underestimating how daft people can be in not seeing what, to me, is "glaringly obvious". I was thinking primarily of plastic sockets and FCUs etc., and it never occurred to me that anyone would dream of relying on faceplate screws as the only means of connecting a CPC to the earth terminals of the actual accessory!

However, what I think is rather daft about 543.2.7 is that it relates only to the situation in which the only incoming earth is a conduit or SWA armour etc. , since exactly the same (electrical) situation arises if the incoming CPC is a core of a cable (a situation presumably far more likely to be encountered by a DIYer than conduit or SWA) and someone connects that CPC (only) to the backbox- yet the reg says nothing about the need for a 'flylead' in that situation!

Kind Regards, John

 

[JohnW2]

Many incidents have happened because what was "glaringly obvious" to many people was not "glaringly obvious" to everyone,

I've just sort-of conceded/agreed with that. However, these exchanges are, in my opinion, getting a little silly, so let me summarise my personal position:

1...When the earth connection arrives as a core in a cable, and if the accessory has any sort of earth terminal (even if only for a metal faceplate) (i.e. excluding things like plastic light switches), I personally would always take the CPC to that terminal and then run a 'flylead' from that terminal to the backbox.

2...In the rare situation in which an existing CPC was not long enough to reach the light switch, I might take it to the backbox, with a flylead going from there to the accessory - but that's a 'swings and roundabouts' situation since there will inevitably be an extra 'joint' in the CPCs route to the accessory, whether by extending it or at the backbox terminal.

3...Since it corresponds with many people's views of what should be done ('best practice') and since it certainly does not do harm, my advice to anyone else would be as above.

4...However, despite all of the above, I continue to wonder whether anyone has ever suffered a 'significant electric shock' (i.e. excluding static discharges) by touching a faceplate screw, which suggests to me that the theoretical risk is so low as to not really need consideration. One can, as you have done, invoke the fact that one-can say that it 'never happens' but, as I have attempted to illustrate, application of that approach in general would make life, as we know it, almost impossible.

[in writing the above, I've just realised that the update to the forum software appears to have caused us to loose the options for for bulleted/numbered lists and/or indenting of text; I'll raise that issue elsewhere ]

Kind Regards, John