BS7671:2018 Proposed Changes

[davesparks]

Then why not do away with that possible problem and go back to TN-S?
Cost is the reason pure and simple.
no risk of raising the earth to mains potential due to open pen conductor and no diverted neutral currents.
Earth can still fail of course.

I would imagine the fact that it is almost impossible to do that would have something to do with it.
Also a TNS system these days would not be as good as it was due to the type of cable used these days. The old TNS systems relied in part on the lead sheath being in contact with the earth and forming one large earth electrode, modern plastic insulated cables won't offer this advantage.
And as you say, the earth can still fail.

 

[Toneyz]

I love how the supply authorities issue becomes the installers problem!

But remember that the supplier does not have to provide a earth facility.

 

[Pete999]

But remember that the supplier does not have to provide a earth facility.

Yes the reason for this edict is the failing of older U/G cables or degrading with age

 

[Flanders]

Will be interesting seeing how many domestic installions get condemned for no earth rods, I noticed that now all lighting circuits in domestic installations will have to be rcd protected which is just belt and braces to make sure rcds are fitted on all circuits in a house .

 

[Ian1981]

Ca

But remember that the supplier does not have to provide a earth facility.

but 99% of the time they will unless there's a good reason not to

 

[Toneyz]

What happens if you live in a block of flats ? or if your posh apartments

 

[Andy78]

Will be interesting seeing how many domestic installions get condemned for no earth rods, I noticed that now all lighting circuits in domestic installations will have to be rcd protected which is just belt and braces to make sure rcds are fitted on all circuits in a house .

I can still think of plenty of types of circuits that have no requirement for RCD protection, installation method dependant of course.

 

[Andy78]

What happens if you live in a block of flats ? or if your posh apartments

Flat below will have to find a use for the copper coated ceiling decoration they now have.

 

[davesparks]

What happens if you live in a block of flats ? or if your posh apartments

Well the sensible people will install earth electrodes connected to the MET of the incoming supply to the building.

The less sensible people will be clipping green and yellow cables down the outside of the building to earth rods.

 

[Andy78]

Well the sensible people will install earth electrodes connected to the MET of the incoming supply to the building.

The less sensible people will be clipping green and yellow cables down the outside of the building to earth rods.

Hahahaha can just imagine that. One for each flat

 

[Ian1981]

Flat below will have to find a use for the copper coated ceiling decoration they now have.

The incoming earth

Well the sensible people will install earth electrodes connected to the MET of the incoming supply to the building.

The less sensible people will be clipping green and yellow cables down the outside of the building to earth rods.

depends if each flat has an individual supply through their own meter and not one large incoming cable supplying a bemco.

 

[Flanders]

I can still think of plenty of types of circuits that have no requirement for RCD protection, installation method dependant of course.

Yes i guess your right ,
Smoke detectors
Intruder alarm
Water heater
Door bell

 

[davesparks]

Hahahaha can just imagine that. One for each flat

Yes, just like you see with main bonds to gas meters 'cos it has to be at the meter'

 

[Andy78]

Yes i guess your right ,
Smoke detectors
Intruder alarm
Water heater
Door bell

Cooker circuit, electric heaters, distribution circuits to outbuildings, boilers ........

I reckon if you tried you could easily design a domestic install without a single RCD in the CU.

 

[Ian1981]

Cooker circuit, electric heaters, distribution circuits to outbuildings, boilers ........

I reckon if you tried you could easily design a domestic install without a single RCD in the CU.

How each circuit in the bathroom has to be rcd protected