Earthing armoured cable.

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AlexCarp

A 2.5mm armoured cable from a CU, running underground to a garden shed. If the cable has three insulated cores, L, N & E, does the outer metal armoured protection sheath need to be earthed? Thanks.
 
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Only really needs bonding one end but yes needs bonding. The taking of an earth from a main building to an out building is a complex question the amount of bonded metal in the outbuilding the distance to out building and the proximity of other buildings plus of course the type of earth used in the main building all have to be taken into consideration.

Arriving on site one has a look around and then one decides it not a fixed thing but a skilled judgement.

Were taking the main building earth to an out building the earth loop impedance is a very important factor and using the SWA as well as the core can reduce the earth loop impedance to an acceptable level.

You say 2.5mm² so I would assume 13, 16, or 20 amp Fuse/MCB to feed which means 2.42Ω - 13A fuse, 2.87Ω 16A B type MCB or 2.3Ω for 20A B type MCB these figures will be reduced with type C (half) or type D (quarter) so what readings did you get? Also don't forget to check tripping time of RCD must be under 40ms and of course that it does trip at 30ma.
 
Only really needs bonding one end but yes needs bonding. The taking of an earth from a main building to an out building is a complex question the amount of bonded metal in the outbuilding the distance to out building and the proximity of other buildings plus of course the type of earth used in the main building all have to be taken into consideration.

Plus whether or not there are extraneous conductive parts in the outbuilding.
 
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Thanks. A 16A mcb and a 63A 30mA RCD at the CU end. The RCD only does the outside circuit. So all armoured cable, even if supplied with an insulated earth conductor must be earthed at the CU end. I assume this is in case a pitch folk penetrates the cable touching the outer metal sheath and a live, or whatever. The metal sheath is just an outer covering like then plastic coverings of the cable. As long as one of the cores is an earth the outer metal sheath is irrelevant in normal operation - if an appliance has a fault the metal outer sheath plays no part. It is only when the cable is severed I can see earthing then to come into play.

Are you saying that in some circumstances the outer metal sheath is better earthed at the shed end with an earth rod?
 
EFLImpudence has nothing to add to this thread, except noise. I fear he doesn't know. Maybe he thinks he is the Part P Police. I would advise most people to do homework first as if you get three electricians in, you will get three different solutions and different interpretations of the regs. Most electricians did not know earth bonding before the 17th regs. I knew one who insisted that the bathroom bonding HAD to go back to the meter. Even I knew it did not and that the appliance in the bathroom just needed to be linked to each other. Another who would run cables over kitchen worktops behind the tiles horizontally. Read the threads on here and see the different interpretations. Electricians generally are a poor trade craft-wise, just look at the appalling state of the wiring around most meters that are slapped all over with no idea of neatness and not even clipped. 25mm cables loose so kids can pull them off.
 
Only really needs bonding one end but yes needs bonding

No it doesn't, it needs earthing

Thanks. So can this outer metal sheath may be earthed at any end? Or earthed at both ends? Or say to the earth conductor at any point along its length (if say an external socket is say on the run from the house to the shed)?
 
EFLImpudence has nothing to add to this thread, except noise. I fear he doesn't know. Maybe he thinks he is the Part P Police. I would advise most people to do homework first as if you get three electricians in, you will get three different solutions and different interpretations of the regs. Most electricians did not know earth bonding before the 17th regs. I knew one who insisted that the bathroom bonding HAD to go back to the meter. Even I knew it did not and that the appliance in the bathroom just needed to be linked to each other. Another who would run cables over kitchen worktops behind the tiles horizontally. Read the threads on here and see the different interpretations. Electricians generally are a poor trade craft-wise, just look at the appalling state of the wiring around most meters that are slapped all over with no idea of neatness and not even clipped. 25mm cables loose so kids can pull them off.

Go fu ck your self. You came for advice and just because you don't like the advice you were given suddenly all electricians are useless.

Leave this forum and do not come back ever again.
 
EFLImpudence has nothing to add to this thread, except noise. I fear he doesn't know. Maybe he thinks he is the Part P Police. I would advise most people to do homework first as if you get three electricians in, you will get three different solutions and different interpretations of the regs. Most electricians did not know earth bonding before the 17th regs. I knew one who insisted that the bathroom bonding HAD to go back to the meter. Even I knew it did not and that the appliance in the bathroom just needed to be linked to each other. Another who would run cables over kitchen worktops behind the tiles horizontally. Read the threads on here and see the different interpretations. Electricians generally are a poor trade craft-wise, just look at the appalling state of the wiring around most meters that are slapped all over with no idea of neatness and not even clipped. 25mm cables loose so kids can pull them off.

of course he knows. but why would anyone give an incompetent person valuable advise to such who is abusive and may put lives at risk. and as for your other ranting s probably best you jog on.
 

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