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Ring Main Joint Box

PG
A kitchen worktop twin S,O, is to be relocated horizontally by about 60cm. 

The ring final cct (RFC) is cabled in buried T&E and the galv' steel back-box is flushed into the plaster/brick wall.

The RFC T&E extension cabling will be buried under plaster, covered in plastic capping along the horizontal  prescribed zone. Visually, it would be reasonable for an electrician to be aware that the route may contain cable(s).

The circuit is RCD protected.

The intent is touse insulated crimp and double insulating tape the jointed cables within the existing box to achieve a maintenance free connection, A 2mm thick (fabricated) plate was to be used to cover the back box and provide additional mechanical protection. The box would then be plastered over.


The questions are:-

1. How many would consider the steel plate back box cover a desirable feature or would a simple plastic cover suffice?

2. Should the original back box be left  unearthed?


Thanks in advance.
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    PG:

    Thanks - I have never earthed steel capping and was thinking that it may be as well not to introduce earth potential in the box.




    Rewire - some cable drops in mini-conduit; some under plastic capping; some under steel capping. The last gives one the opportunity to demonstrate to the children the magic walls with mini-magnets. ? The implication of the steel capping is that one needs to be careful, very careful, when pulling in the new cables.


    Capping does not satisfy the requirements of 522.6.204. It does not have to be earthed, but the circuit should have additional protection by RCD. I suggest that a steel back box should be treated in a similar way. No need to earth, but even if it was, it would not be a substitute for additional protection.

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  • 0

    PG:

    Thanks - I have never earthed steel capping and was thinking that it may be as well not to introduce earth potential in the box.




    Rewire - some cable drops in mini-conduit; some under plastic capping; some under steel capping. The last gives one the opportunity to demonstrate to the children the magic walls with mini-magnets. ? The implication of the steel capping is that one needs to be careful, very careful, when pulling in the new cables.


    Capping does not satisfy the requirements of 522.6.204. It does not have to be earthed, but the circuit should have additional protection by RCD. I suggest that a steel back box should be treated in a similar way. No need to earth, but even if it was, it would not be a substitute for additional protection.

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