Galvanized steel channelling. Reliable earthing?

[skyblob]

I'm needing to install over blockwork (behind dot and dab plaster) in a number of areas which are outside the 522.66(v) zones.

That galvanized pressed steel channelling which fixes over wires. I'd guess it classifies as "have earthed armouring"?(or does it not?)
- But getting a reliable low impedance earth between the sections of it isn't obvious. Clamping bonding wires beneath a screw head/washer seems like the only way, but it feels like a bodge, and doesn't strike me as being reliable for a contact long term.

Is this normal way to go?

 

[Lectrician]

That is not the way to satisfy the regulation.

You should be looking at steel conduit, SWA, MI etc, or routing your cables in safe zones, or forming safe zones for them (move or add a socket for example).

You cannot use FP200.

You can use a new product which I forget the name of at the moment. Guardian or something similar.

Can you draw a diagram, take a photo or describe exactly your routes?

 

[Chri5]

Earth loops, lugs on either end, terminated on 'bright' metal with star washers and then topped with some grease to prevent oxide / rust breaking down contact.

If you are placing cable in it then it's metal containment and earthing is required.

 

[Chri5]

Lelectrician- surely protected metal containment (as does conduit) allows deviation from safe zone requirements ?

 

[Lectrician]

I have never considered using capping to run outside safe zones - even if earthed satisfactorily, I see it as a bodge. You would have inaccessible joins where the earths joint to the capping.

 

[RF Lighting]

Lelectrician- surely protected metal containment (as does conduit) allows deviation from safe zone requirements ?

If you read 522.6.6 it is quite specific about what sort of protection you must use if a cable is installed outside a safe zone, and steel capping does not comply.

 

[ColJack]

capping does not qualify as it is not enclosing the wiring, you can still get at it from the back without hitting earthed metal first..

capping does not qualify as mechanical protection since it's too thin and you can easily drive a nail trough it..

for those of you without the big red book ...

522.6.6 A cable concealed in a wall or partition at a depth of less than 50 mm from a surface of the wall or partition shall:

(i) incorporate an earthed metallic covering which complies with the requirements of these Regulations for a protective conductor of the circuit concerned, the cable complying with BS 5467, BS 6346, BS 6724, BS 7846, BS EN 60702-1 or BS 8436, or

(ii) be enclosed in earthed conduit complying with BS EN 61386 and satisfying the requirements or these Regulations for a protective conductor, or

(iii) be enclosed in earthed trunking or ducting complying with BS EN 50085 and satisfying the requirements or these Regulations for a protective conductor, or

(iv) be mechanically protected against damage sufficient to prevent penetration of the cable by nails, screws and the like, or

(v) be installed in a zone within 150 mm from the top of the wall or partition or within 150 mm of an angle formed by two adjoining walls or partitions. Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear. Where the location of the accessory, point or switchgear can be determined from the reverse side. a zone formed on one side of a wall of 100 mm thickness or less or partition of 100 mm thickness or less extends to the reverse side.

---------------------------------------

522.6.7 Where Regulation 522.6.6 applies and the installation is not intended to be under the supervision or skilled or instructed person, a cable installed in accordance with Regulation 522.6.6 (v). and not complying with Regulation 522.6.6 (i), (ii), (iii) or (iv), shall be provided with additional protection by means of an RCD having the characteristics specified in Regulation 415.1.1

 

[Lectrician]

Many people think you can use FP200 or other FP equivs - you cannot. You can use FP400 which is effectively armoured FP200.

 

[skyblob]

Thanks guys. As much as I suspected.

Plenty now for me to look at, very helpful.

Rgds

 

[electronicsuk]

By the time you have the added depth of the plasterboard and adhesive, you surely wont be too far off having 50mm burial depth for the wiring?

 

[ColJack]

how frickin thick do you think plasterboard is?

12mm at most with a bed of about 18mm of adhesive ( once squished )..
that makes 30mm.. and that's to the brick. the cable sits on top of the brick and is about 7-10mm thick.. so the cable is only 20-25mm from the surface of the wall..

 

[mickroyds]

What about if it was rendered instead of plasterboard it could be thinner still, so is that plastic capping outlawed ?.

Mick.

 

[ColJack]

no, capping is used as an alternative to clips and is there ( despite teir protests to the oposite ) to protect the cable from the plasterers trowel amongst other things..
use for straight runs and drops it also potentially allows for easier replacenent of a cable if needed....

 

[nozspark]

You have several options....

1. keep it in zones
2. install cables in earthed steel conduit
3. use a suitable cable... (SWA, MICC or Flexishield/guardian)

and RCD the cable

If you only need a cut of guardian cable then BATT cables will supply... I've just bought 10m 1.5mm T&E... £2/m + £15 small order/next day delivery + VAT

TBH I should have bought a 100m and ebayed what I didn't use!!

 

[ColJack]

you only need to RCD the cable in option 1 above, options 2 and 3 negatge the need..