Metal partition walls

[Welchyboy1]

Is it now a requirement to bond metal partition walls or use rcd protection for cables wired within it, when installed in a commercial environment?

I thought i read it somewhere in an amendment but cant find it again now?

thank you

 

[Andy78]

522.6.103 is the requirements for cables within metallic walls. Yes to RCD protection unless you fulfil one of the other requirements of the reg to avoid doing so.

 

[dingledong]

Now that is how a thread is supposed to be a question and a no nonsense answer

 

[Welchyboy1]

Yes thanks andy, that does give you the get out of under supervision of skilled and instructed persons for commercial environments, which this job would be under

does anybody bond metallic walls? I cant really see it as a requirement or regulation but its definatley something that could lead to a large chunk of live material in a building

would it be a good practice to supplementary bond at least?

 

[Andy78]

You should bond the exposed structural steel of a building and any accessible extraneous conductive part. I don't think the metal structure of the walls falls under this though.

Just because a setting is a commercial one does not automatically mean that the installation is under the supervision of skilled or instructed persons.

 

[Welchyboy1]

Just because a setting is a commercial one does not automatically mean that the installation is under the supervision of skilled or instructed persons.

thanks andy

I understand this and this job is definitely in that category, its only the lighting switch drops that would not be rcd protected
but im tempted to put them on rcbos too, as ive seen plenty of numptys drill into them anyways, supervised or not

 

[davesparks]

And an RCBO will stop it being drilled in to how?

 

[Pete999]

Just protect it with a RCD not that expensive is it and after all it's your name on the cert, safety first

 

[Resu]

And an RCBO will stop it being drilled in to how?

This thread was quite civilised until this reply! You know what he means!

 

[davesparks]

This thread was quite civilised until this reply! You know what he means!

What was uncivilised about that? Maybe I didn't phrase it very well but it's a genuine question.

How does an RCD assist in preventing someone from drilling through a cable?
The answer as far as I know is that it doesn't, so why is it the go-to method of protecting buried cables which might be drilled in to?

All it is doing is providing a means of reducing the danger which may arise, it does nothing to prevent it happening.

If the cable is protected an RCBO and someone drills through the cable shorting N to E rather than L to E or N then they will be no better off than if there was no RCD protection, there is still just as much fire risk from that fault even after the RCBO has disconnected the (Undamaged) L conductor!

 

[Adam W]

What was uncivilised about that? Maybe I didn't phrase it very well but it's a genuine question.

How does an RCD assist in preventing someone from drilling through a cable?
The answer as far as I know is that it doesn't, so why is it the go-to method of protecting buried cables which might be drilled in to?

All it is doing is providing a means of reducing the danger which may arise, it does nothing to prevent it happening.

If the cable is protected an RCBO and someone drills through the cable shorting N to E rather than L to E or N then they will be no better off than if there was no RCD protection, there is still just as much fire risk from that fault even after the RCBO has disconnected the (Undamaged) L conductor!

I suppose in the same way a seatbelt doesn't help prevent a collision.

 

[Welchyboy1]

What was uncivilised about that? Maybe I didn't phrase it very well but it's a genuine question.

How does an RCD assist in preventing someone from drilling through a cable?
The answer as far as I know is that it doesn't, so why is it the go-to method of protecting buried cables which might be drilled in to?

All it is doing is providing a means of reducing the danger which may arise, it does nothing to prevent it happening.

If the cable is protected an RCBO and someone drills through the cable shorting N to E rather than L to E or N then they will be no better off than if there was no RCD protection, there is still just as much fire risk from that fault even after the RCBO has disconnected the (Undamaged) L conductor!

Well, Let me explain it to you........ If the nail or screw hits just the live and then the frame, it will then energise the whole frame without operating the mcb or rcbo, and likely sit like that for some time, if someone now touches a part of this frame and forms a path to earth, then i for one would rather it be rcd protected than not

a plumber died like this and so did a young mum

its also likely that no amount of IR testing will find this kind of fault

 

[Resu]

What was uncivilised about that? Maybe I didn't phrase it very well but it's a genuine question.

How does an RCD assist in preventing someone from drilling through a cable?
The answer as far as I know is that it doesn't, so why is it the go-to method of protecting buried cables which might be drilled in to?

All it is doing is providing a means of reducing the danger which may arise, it does nothing to prevent it happening.

If the cable is protected an RCBO and someone drills through the cable shorting N to E rather than L to E or N then they will be no better off than if there was no RCD protection, there is still just as much fire risk from that fault even after the RCBO has disconnected the (Undamaged) L conductor!

Providing additional protection by means of an RCD won't necessarily help someone if they were to damage the cable but as you have mentioned it reduces the risk of danger. What more can we do? You can only make an installation safe to a certain point without it getting rediculous.

It seemed to me like you were having a dig by asking a what you did, apologies for interpreting it wrong.

 

[davesparks]

Well, Let me explain it to you........ If the nail or screw hits just the live and then the frame, it will then energise the whole frame without operating the mcb or rcbo, and likely sit like that for some time, if someone now touches a part of this frame and forms a path to earth, then i for one would rather it be rcd protected than not

a plumber died like this and so did a young mum

But if that cable had been protected with steel conduit or similar the damage would likely not have happened in the first place or else the protective device will have operated.

And if any part of that metal frame is exposed to touch it should be bonded.

I would not trust an RCD over an earthed metal protection any day of the week, as they get cheaper and cheaper they become less and less reliable.

 

[davesparks]

Providing additional protection by means of an RCD won't necessarily help someone if they were to damage the cable but as you have mentioned it reduces the risk of danger. What more can we do? You can only make an installation safe to a certain point without it getting rediculous.

It seemed to me like you were having a dig by asking a what you did, apologies for interpreting it wrong.

But it only reduces the danger sometimes and even then it might not work unless the test button has been pushed at the correct intervals.

A bit of steel conduit doesn't need its button pressed every 3 months and will stop the casual eejit attempting to put picture hook nails or b&q drill bits through it.

 

[CockneyReject]

thanks andy

I understand this and this job is definitely in that category, its only the lighting switch drops that would not be rcd protected
but im tempted to put them on rcbos too, as ive seen plenty of numptys drill into them anyways, supervised or not

Whats the the building going to be when it's done mate?

galv pipe on your switch and socket drops is the way I'd go and there's bound to be the odd leg of a lighting circuit that's been ran through the metal partition even at height so it's a good idea to use RCBO's aswell to cover those unless you know where every inch of the wiring is ran

 

[ayjay]

Young mother electrocuted as she mopped up water from leaky boiler died after catalogue of workmen's errors | Mail Online

 

[davesparks]

Young mother electrocuted as she mopped up water from leaky boiler died after catalogue of workmen's errors | Mail Online

I assume you are trying to illustrate the point that we as electricians should be installing and securing cables in such a way that they are not likely to be penetrated by plasterboard screws?

 

[ayjay]

exactly my freind
all metal should be bonded down to earth using lugs and m4 brass nuts and bolts
that includes the metalwork of grid ceilings as well
further
no twe should be passed through the existing oblong holes in upright metal studwork
all should have a plastic bush and a lock ring at the centre of said partition upright when going through

 

[davesparks]

That's not what I said!

There's no need to go bonding every bit of metal, only the bits which are liable to introduce unwanted potentials in to an installation and are available to touch.

For the rest of it the cables etched need to be installed in such a way that they are protected from damage or otherwise creating a dangerous situation.

 

[ayjay]

its common sence though, metal partitioning is sharp on twe the plasterboarders use what ever lenght screws are given to them
all of the metal needs to be grounded
the 22 year old girl would hav survived if the metal had been earthed and rcd--d

 

[davesparks]

its common sence though, metal partitioning is sharp on twe the plasterboarders use what ever lenght screws are given to them
all of the metal needs to be grounded
the 22 year old girl would hav survived if the metal had been earthed and rcd--d

What metal? It didn't say anything about a metal partition it could just as easily have been timber studwork, it's easier to see how a screw would get into the cable if it was as they get clipped to the studs and the screw could go in at an angle.

And how on earth do you know with such certainty an RCD would have saved her? Would the RCD have been tested every 3 months as needed?
Did she have no undetected heart condition?
Did her body have the impedance that is used as the standard average for calculating the 30mA/50V?

 

[Knobhead]

Ayjay AKA David Cockburn.

There’s a lot more to that story if you care to investigate. It’s been dragged up so many times it’s getting tedious. Don’t believe all the Daily Mail tells you, look for the inquest findings.

As for the usual blithe suggestion of fitting RCBO’s to everything as an instant cure all, have a look at the shortfalls in their design. Which I think is what Dave alluded to.

 

[Welchyboy1]

Whats the the building going to be when it's done mate?

galv pipe on your switch and socket drops is the way I'd go and there's bound to be the odd leg of a lighting circuit that's been ran through the metal partition even at height so it's a good idea to use RCBO's aswell to cover those unless you know where every inch of the wiring is ran

the area is in a school, new build, they will be hiring the building out for business events meetings, training courses and adult learning

not a school teaching area for usual school students, comprises of small office, kitchen, main training area, lobby, reception room

galv tube is an option and i have used this method in other areas of the school which has older disboards, all my distribution board switchgear will be new merlin gerin/schneider, which i am usually quite happy with the reliability of

 

[CockneyReject]

I'd stick to the galv pipe if it was my job then fella, as good as the Merlin Gerin style Schneider stuff is RCD/RCBO's can't compete with good old fashioned installation methods and if left to it without regular test intervals even the better quality ones can fall short when the time comes I'd never rely solely on a mechanical device for protection against penetration