Hi,
I hope someone can help me out here. I have tried to find the answers to this in the wiki and in past threads, but can't find the answers for when the house is wired TT.
I have a garage with RCD and MCBs. It is currently linked to the house with an overhead cable. The house is a TT system with a single RCD and wired fuses.
The overhead cable is a very poor lash up that was there when I bought the property 16 years ago and could have easily been there for 10 years before that. (Yep, I should have changed it years ago... ).
It is a length (10ft?) of 4mm T & E wrapped around a length of what looks like washing line. It runs about 7feet off the floor - a foot above a gate and fence. The wire has no mechanical protection and has been exposed to UV for decades.
It has become an issue because the fence and gate is to be replaced and it is rather 'in the way'.
Obviously I would like to replace it. It is just at the thinking stage at the moment.
I have two questions:
Firstly, if I use SWA cable under flag stones does this need to be buried? I have read elsewhere that cables should be 18" deep or more, but if covered by a flag stone patio is this neccesary? I was thinking it might actually be safer to run the cable just under the flags, perhaps with yellow warning tape over it, as then anyone who takes the flags up would see it straight away?
Secondly, the distance from the house to the furthest socket point is quite long, maybe 40ft. The soil outside the rear of the garage is very deep and moist, the water table being quite high. It looks like an excellent site for an earth spike and I am wondering if fitting the garage with it's own earth electrode and creating a local TT system might be a better option?
The aricle that is linked to from this forum whenever garages are mentioned, the IET one by John Ware, says that an outbuilding on a TT system must not be connected to the earth of the incomming SWA cable. This article assumes the main dwelling is PME.
"Where the installation in the garage is supplied by an armoured cable, the armour or any protective conductor in the cable must not be
connected to and must not be simultaneously-accessible
with any exposed-conductive-parts in the outbuilding."
Question: Does this also apply to installations where the house is TT?
Is is verbotten to link two TT systems together? The earth spikes would be about 40ft apart. If so, just out of academic interest, why so?
Thanks.
I hope someone can help me out here. I have tried to find the answers to this in the wiki and in past threads, but can't find the answers for when the house is wired TT.
I have a garage with RCD and MCBs. It is currently linked to the house with an overhead cable. The house is a TT system with a single RCD and wired fuses.
The overhead cable is a very poor lash up that was there when I bought the property 16 years ago and could have easily been there for 10 years before that. (Yep, I should have changed it years ago... ).
It is a length (10ft?) of 4mm T & E wrapped around a length of what looks like washing line. It runs about 7feet off the floor - a foot above a gate and fence. The wire has no mechanical protection and has been exposed to UV for decades.
It has become an issue because the fence and gate is to be replaced and it is rather 'in the way'.
Obviously I would like to replace it. It is just at the thinking stage at the moment.
I have two questions:
Firstly, if I use SWA cable under flag stones does this need to be buried? I have read elsewhere that cables should be 18" deep or more, but if covered by a flag stone patio is this neccesary? I was thinking it might actually be safer to run the cable just under the flags, perhaps with yellow warning tape over it, as then anyone who takes the flags up would see it straight away?
Secondly, the distance from the house to the furthest socket point is quite long, maybe 40ft. The soil outside the rear of the garage is very deep and moist, the water table being quite high. It looks like an excellent site for an earth spike and I am wondering if fitting the garage with it's own earth electrode and creating a local TT system might be a better option?
The aricle that is linked to from this forum whenever garages are mentioned, the IET one by John Ware, says that an outbuilding on a TT system must not be connected to the earth of the incomming SWA cable. This article assumes the main dwelling is PME.
"Where the installation in the garage is supplied by an armoured cable, the armour or any protective conductor in the cable must not be
connected to and must not be simultaneously-accessible
with any exposed-conductive-parts in the outbuilding."
Question: Does this also apply to installations where the house is TT?
Is is verbotten to link two TT systems together? The earth spikes would be about 40ft apart. If so, just out of academic interest, why so?
Thanks.