If I bury a bonding cable in a wall, <50mm, no mechanical protection etc, does it need RCD protection?
Conundrum
- Thread starter ban-all-sheds
- Start date
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S
sparkyspike
Protection from what? Ze Germans? 
H
holmslaw
..
What would that achieve?
I know 522.6.6 & 7 do not specifically refer to protection of live conductors, but that is their intention.
Bury away, Bas.
I know 522.6.6 & 7 do not specifically refer to protection of live conductors, but that is their intention.
Bury away, Bas.
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Add telephone cable, alarm cable, tv/sat cable.......
How do you RCD protect an earth bonding cable??
I think he's seeing it the same way as me. 522.6.6 states 'cable'.
What would you define as a cable? It's a shame they don't list it in definitions.
H
holmslaw
..
Please read the Summer 2008 Wiring Matters magazine...
http://www2.theiet.org/Publish/WireRegs/WiringMatters/
... and then never use that phrase again!
ding,
I understand what you are saying (incorrect terminology) and I was fully aware of what I typed. The reason I wrote what I did is because this is a DIY forum and calling it a MEB gets away from the fact that this cable should be at earth potential and contains no live (line & neutral) conductors, so as it is at earth and is a bonding conductor I thought it best to use laymans terms..
I understand what you are saying (incorrect terminology) and I was fully aware of what I typed. The reason I wrote what I did is because this is a DIY forum and calling it a MEB gets away from the fact that this cable should be at earth potential and contains no live (line & neutral) conductors, so as it is at earth and is a bonding conductor I thought it best to use laymans terms..
Haha, noz! You don't get away that easily.
Why not use an even easier-to-understand correct term and just call it a protective conductor?
(What did you think you meant by MEB , by the way? That organisation disappeared a long time ago!)
Why not use an even easier-to-understand correct term and just call it a protective conductor?
(What did you think you meant by MEB , by the way? That organisation disappeared a long time ago!)
Okay, okay...
I'll get me' coat!!
I'll get me' coat!!
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What is a cable?
I think about a 183 meters was part of the metric system a 100 fathoms = 1 cable and 10 cables = 1 mile. (before the French go involved) Moving away from unit of length it was always a mixture of items having a core with other items surrounding it. Moving into the electrical, again a mixture of components, normally including wires and isolating materials, often including as with original cable some string. I would not consider an earth wire as being a cable until we reach the larger sizes at 16mm one may refer to it as cable.
On to real question as to non earth protected wires in a wall there has been an obvious over sight as can’t really protect SELV cables with earths or RCD’s or any wire at earth potential.
The problem arises where one tries to work out how much is wrong and it would be easy to extend it to all cables within a wall in that having proved there is an error the whole section maybe should be ignored until the obvious faults have been removed from the section.
So what happens to an isolated class II supply to a single item? For example if the isolation transformer for a shaver was in the loft and supply wires came down the wall to a socket beyond the bounds of Zone 2.
If there was to be for example a nail put through the cable and earthed either of the two cables then there would be a danger and it would be right to have some form of protection but the only units I have seen to do this in themselves introduce and earth.
First was with DC cranes in a steel works where two bulbs bridged the supply lines and were earthed at centre point and earth fault would make light bright.
On the 220 volt control of a batching plant again through an isolating transformer a monitoring device did using electronics the same as the crane system and switched on a lamp in operators cab if there was a fault but in itself as with crane introduced and earth on what should have been an earth free system.
So what are the answers?
Eric
I think about a 183 meters was part of the metric system a 100 fathoms = 1 cable and 10 cables = 1 mile. (before the French go involved) Moving away from unit of length it was always a mixture of items having a core with other items surrounding it. Moving into the electrical, again a mixture of components, normally including wires and isolating materials, often including as with original cable some string. I would not consider an earth wire as being a cable until we reach the larger sizes at 16mm one may refer to it as cable.
On to real question as to non earth protected wires in a wall there has been an obvious over sight as can’t really protect SELV cables with earths or RCD’s or any wire at earth potential.
The problem arises where one tries to work out how much is wrong and it would be easy to extend it to all cables within a wall in that having proved there is an error the whole section maybe should be ignored until the obvious faults have been removed from the section.
So what happens to an isolated class II supply to a single item? For example if the isolation transformer for a shaver was in the loft and supply wires came down the wall to a socket beyond the bounds of Zone 2.
If there was to be for example a nail put through the cable and earthed either of the two cables then there would be a danger and it would be right to have some form of protection but the only units I have seen to do this in themselves introduce and earth.
First was with DC cranes in a steel works where two bulbs bridged the supply lines and were earthed at centre point and earth fault would make light bright.
On the 220 volt control of a batching plant again through an isolating transformer a monitoring device did using electronics the same as the crane system and switched on a lamp in operators cab if there was a fault but in itself as with crane introduced and earth on what should have been an earth free system.
So what are the answers?
Eric
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They're Main Protective Bonding Conductors connected to form Protective Equipotential Bonding.
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