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cables buried in walls


Robin Spark

Question

Apart from erthed swa or metal conduit, what other cables can you use when buried in wall less than 50 mm from surface so as to not need 30ma RCD.

Could you use MICC or FP rated cables?

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13 answers to this question

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Interesting that we are talking about nail penatration.

The cables mentioned are not designed to withstand any form of nail penatration, they are designed so that if this does occur the safety device protecting the circuit will discconect from the mains supply.Therefore protecting users and building from harm or damage respectfully.

The outer mettalic sheath is in constant contact with the cpc, so any penatration should cause the RCD to disconnet from supply, protecting the circuit, building and user.

You been at that bottle again Greeny ? The idea of these cables is to install without an RCD. :)

Deke

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Apart from erthed swa or metal conduit, what other cables can you use when buried in wall less than 50 mm from surface so as to not need 30ma RCD.

Could you use MICC or FP rated cables?

So long as your cable meets the specified BS standards,

as per page 100 BRB, Reg 522.6.6 (i), where:-

BS 5467:

Armoured cables having thermosetting insulation

BS 6346:

Armoured cables having pvc insulation

BS 6724:

Armoured cables having thermosetting insulation and low emission of smoke and corrosive gases when affected by fire

BS 7846:

Armoured fire-resistant cables having thermosetting insulation and low emission of smoke and corrosive gases when affected by fire

BS EN 60702-1:

Mineral insulated cables with a rated voltage not exceeding 750 V

BS 8436:

300/500 V screened cables having low emission of smoke and corrosive gases when affected by fire, for use in thin partitions and building voids

As each of the bullet points are an 'OR' selection

(i) OR (ii) OR (iii) etc..

NOT

(i) AND (ii) AND (iii)

You ONLY need the protection against Nail impact IF it is NOT one of the specs detailed in point (i).

Thus if your MICC is to BS EN 60702-1 Then YES you can use MICC;):)

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no. they won't stop penetration of a nail etc as specifically required.

incidentally swa does not also

just to correct you there Lostit...

You DO NOT need nail impact resistance if it has an appropriate earth metallic covering!

The bullet points or reg 522.6.6 are 'OR' NOT 'AND'

;)Guiness Drink:x

{page 100 BRB}

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So long as your cable meets the

BS 8436:

300/500 V screened cables having low emission of smoke and corrosive gases when affected by fire, for use in thin partitions and building voids

what kind of cable is this? Is it not FP?

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ahROTFWL

;)

back in the real world you not ever likely to install such cables tho O)

concur......Applaud Smiley

But real world.... IMHO just stuff on a

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You been at that bottle again Greeny ? The idea of these cables is to install without an RCD. :)

Deke

Yes you are right and the inclusion of the RCD in my comment should be changed to MCB ROTFWL

Interestingly in the connections mag this month there is a full article on the use of this type of cable.

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what kind of cable is this? Is it not FP?

the foil on FP is not think enough to withstand enough current to flow to trip a MCB. so if you stick a nail in it, the foil is likely to melt away before power goes off. 8436 is similar, but the foil is thicker and can withstand the current needed to trip breaker

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There is also a cable called Flexishield which can be used . Looks like FP200 but sheath will not melt when pierced.

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Interesting that we are talking about nail penatration.

The cables mentioned are not designed to withstand any form of nail penatration, they are designed so that if this does occur the safety device protecting the circuit will discconect from the mains supply.Therefore protecting users and building from harm or damage respectfully.

The outer mettalic sheath is in constant contact with the cpc, so any penatration should cause the RCD to disconnet from supply, protecting the circuit, building and user.

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Interesting that we are talking about nail penatration.

The cables mentioned are not designed to withstand any form of nail penatration, they are designed so that if this does occur the safety device protecting the circuit will discconect from the mains supply.Therefore protecting users and building from harm or damage respectfully.

The outer mettalic sheath is in constant contact with the cpc, so any penatration should cause the RCD to disconnet from supply, protecting the circuit, building and user.

i think because it mentions that in the regs some/me have thought that is the object but now clearly its not

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