UK Exposed securing screws

[Philip Shields]

Some of the plastic light switches in my home are fixed to plastic back boxes. The metal screws securing these switches are therefore not earthed. An electrician who tested my system insisted that these screws must be hidden by plastic covers - is this necessary?

 

[telectrix]

that "electrician" is talking through his arse. ask him for a regulation number that is contravened. that should shut him up.

 

[DPG]

Wasnt a Mr. Cockburn your electrician was he?

 

[GBDamo]

IF there is no CPC (earth) in the lighting circuit then there is a chance, albeit small, that IF a cable came out of the switch AND landed on the earthing components in the back of the switch AND you then made contact with the screw you would get a shock.

If this happened in a circuit with a CPC then the fuse/MCB/RCD would blow/trip.

A lot of starts would have to align but this is potentially dangerous IF there is no earth in the lighting circuit.

 

[DefyG]

Did he think it was April 1st?

 

[freddo]

IF there is no CPC (earth) in the lighting circuit then there is a chance, albeit small, that IF a cable came out of the switch AND landed on the earthing components in the back of the switch AND you then made contact with the screw you would get a shock.

On a plastic box though it would be almost impossible for a loose wire to float over and touch one of the plate screws.

 

[Flanders]

There is no possibility of the screws becoming live, there no exposed metal part within the plastic back box. So even if there was an exposed live part touching the plastic back box it would never be in contact with the screws . So no the caps over the screws are not necessary but they are sometimes fitted for cosmetic reasons

 

[westward10]

Caps are solely aesthetic they serve no other purpose.

 

[Dartlec]

Sparkyninja covered this in one of his videos regarding earth back box earthing.

Reg 410.3.9(iii) states that provision for fault protection may be omitted for exposed-conductive-parts which are small enough that they cannot be gripped or come into significant reliable contact with the human body

So a socket screw does not count as something that must be earthed for fault protection purposes, even with a metal back box - and certainly not with a plastic one.

Those plastic covers are a PITA when you're trying to do an EICR - In a circuit with no cpc and class 2 switches I'd probably prefer plastic screws if it was a concern.

 

[nicebutdim]

Those plastic covers are a PITA when you're trying to do an EICR - In a circuit with no cpc and class 2 switches I'd probably prefer plastic screws if it was a concern.

Apparently blutac is the answer for removing them.

Hideous looking things.

 

[westward10]

Sparkyninja covered this in one of his videos regarding earth back box earthing.

Reg 410.3.9(iii) states that provision for fault protection may be omitted for exposed-conductive-parts which are small enough that they cannot be gripped or come into significant reliable contact with the human body

So a socket screw does not count as something that must be earthed for fault protection purposes, even with a metal back box - and certainly not with a plastic one.

Those plastic covers are a PITA when you're trying to do an EICR - In a circuit with no cpc and class 2 switches I'd probably prefer plastic screws if it was a concern.

I don't believe you can get Class II light switches.

 

[GBDamo]

On a plastic box though it would be almost impossible for a loose wire to float over and touch one of the plate screws.

You know all I've been installing are grid switches, not common in domestics granted.

Just been looking at domestic switches and you're correct, a near impossibility.

 

[Dartlec]

I don't believe you can get Class II light switches.

That's because they are not a current using appliance I guess? What is the correct term for switches that do not need to be earthed - non-metallic? (parts of them are usually metal at some point)

 

[westward10]

That's because they are not a current using appliance I guess? What is the correct term for switches that do not need to be earthed - non-metallic? (parts of them are usually metal at some point)

All insulated not necessarily meeting the requirements for Class II.