You do not need a CU of any kind, terminate the cable into a metal clad socket and add any others from that, use a 3A switched FCU for lighting.
While not ideal, connecting the armour at one end only could be compliant.
Indoor FCU for outdoor electrics
- Thread starter sergeantash
- Start date
While not ideal, connecting the armour at one end only could be compliant.
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I'll get a photo of the unit that is currently installed into the garage to show you what's there and if its OTT or still usable. Thanks again.
Are we sure this is SWA "steel wire armoured" cable. There is no sign of steel wire armour in the photo of th back of the FCU.
And this raises the question of whether it will be safe ( or even compliant ) to export the earth from the house to the garage.
Are there any service pipes ( gas water oil ) or other extraneous conductive items that enter the garage and may require bonding ?
And this raises the question of whether it will be safe ( or even compliant ) to export the earth from the house to the garage.
Are there any service pipes ( gas water oil ) or other extraneous conductive items that enter the garage and may require bonding ?
Hi Bernard, as mentioned above the armoured element was cut back to the point just before the cabling goes through the house wall, but it is definitely armoured. There are no other services in the garage, just electric.
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How is the steel wire armour terminated at the house end ?
The armour needs to be earthed there other wise protective devices ( fuses MCBs etc. ) will not be able to operate and protect the cable and person when the cable is damaged.
The end of the armouring need to be in the correct gland termination to [1] ensure electrical continuity of the earth to the armouring and [2] to prevent moisture ingress which over time can result in the steel rusting and the electrical continuity being lost.
The armour needs to be earthed there other wise protective devices ( fuses MCBs etc. ) will not be able to operate and protect the cable and person when the cable is damaged.
The end of the armouring need to be in the correct gland termination to [1] ensure electrical continuity of the earth to the armouring and [2] to prevent moisture ingress which over time can result in the steel rusting and the electrical continuity being lost.
It's earthed at the other end.
I assume that is a cynical comment. Or do you know that it has an Earth with an impedance that is low enough to ensure MCBs will operate within the specified time when the cable is damaged with a Live to Armour short ? ( if the Earth at the garage end is via one of the cores then that core could be severed milliseconds before the Live to Armour short occurs which would leave all "earthed" items in the garage at live potential.
Hi Bernard, I appreciate your help, but we've already discussed this in the replies previous to yours, please review the thread.
Having read through the thread I can find NO indication of an Earth in the garage.
An Earth has to be either
[1] a substantial metal rod driven into the ground and tested to ensure it can carry enough current to ensure protective devices operate.
[2] a substantial and mechanically protected metallic conductor from the Main Earth Terminal that is located close to the incoming supply to the meter.
Which have you got in the garage.
An Earth has to be either
[1] a substantial metal rod driven into the ground and tested to ensure it can carry enough current to ensure protective devices operate.
[2] a substantial and mechanically protected metallic conductor from the Main Earth Terminal that is located close to the incoming supply to the meter.
Which have you got in the garage.
Ah sorry, you initially mentioned on the house side, not the garage. I am yet to thoroughly inspect the garage end and will do so hopefully this weekend and provide pictures. I won't action or 'live' anything until I've run it by you guys.
Clearly neither, but the proposal is to earth the armour (to the house's earth) at the the garage end, via the 'earth' core of the SWA. Provided only that the resultant loop impedance etc. is satisfactory (there is no requirement for bonding), that is probably just about acceptable, and probably compliant.
In passing, as for your [1], virtually no domestic earth electrode would have a low enough impedance to facilitate operation of an OPD - whereas, in contrast, virtually no domestic earth electrode would not have a low enough impedance to facilitate the operation of an RCD.
Kind Regards, John
No, it's a statement of fact. Or I thought it was at the time - apologies for misrememberifying, I thought the OP had said it was, not would be/could be.
As JW2 pointed out, you aren't going to get that if the earth is via a rod at the garage end, which was one of your preferred options, so I'm struggling to understand your objections.
Now I'm really struggling.
Please help me out and postulate a damage incident where the armour is penetrated and the earth core is cut before any contact is made between armour and line or neutral which would not have proceeded like that if the armour had been earthed at the source end.
Maybe I'm mistaken, but I definitely get the impression that you aren't taking on board some of the things you are being told.
The initial contacts between the blade ( which is live from contact with the Live ) and low impedance neutral and earth cores could be blown apart before the MCB operates. The blade is then still live when it touches the armouring which is now, following the severance of the earth core, without any connection to earth.
Yes it is a low risk of this precise situation occuring but we are supposed to consider every reasonable risk
Interesting, so does this suggest that the armour should be earthed at both sides, in the house and in the garage?
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