I was just contemplating making a connection to a garden shed and was taking a look at my CU (s!!).....and had some questions regarding the earthing arrangements.
The incoming mains cable from eb looks like it is coated in a 'tar' cloth wrap & has a woven connector marked 'safety earth -do not remove' attached to it (just before it enters the main fuse) which is terminated in a connector box.
However there are no connections to this from the house circuits. I have 3 (!) CU units all connected via their own tails from a block which in turn comes off of the main incoming fuse. The 3 CU's are the standard house box (with 6 circuits) plus a separate dedicated cooker CU and a third CU which looks like it was added later providing a few extra 16A radial circuits in the lounge (& has a few spare outlets from which a shed supply could be taken).
Earth arrangements for all 3 CU's rely on connection / cross connection to the metal conduit which disappears into the concrete floor from all 3 CUs.
Q1: What type of earth is this likely to be?
Q2: Is it sufficient to earth via conduit, or should all 3 CUs also be cross connected & attached to the electricity board earth -it would seem safer in principal?
Q3: We are in the process of having a bathroom fitted & the plumber has laid (in part anyway so far) the cross bonding earth connections -will this go to the electricity board earth or the (one of!) CU units -does it even matter?
Q4: I thought that there was supposed to be a single switch off point (or is this a recent change in regs), or is it ok to have to shut off 3 switches to close off all power?
For info my house is in suburban surrey & was built in 1936. It has clearly been rewired as all cabling is t&e except for one of the ligting circuits which appears to be good similar age twin core (i.e. pvc) but uses a separate earth cable & (metal) conduit for earthing. I presume the incoming mains is as originally installed in 1936.
Thanks for any help!
The incoming mains cable from eb looks like it is coated in a 'tar' cloth wrap & has a woven connector marked 'safety earth -do not remove' attached to it (just before it enters the main fuse) which is terminated in a connector box.
However there are no connections to this from the house circuits. I have 3 (!) CU units all connected via their own tails from a block which in turn comes off of the main incoming fuse. The 3 CU's are the standard house box (with 6 circuits) plus a separate dedicated cooker CU and a third CU which looks like it was added later providing a few extra 16A radial circuits in the lounge (& has a few spare outlets from which a shed supply could be taken).
Earth arrangements for all 3 CU's rely on connection / cross connection to the metal conduit which disappears into the concrete floor from all 3 CUs.
Q1: What type of earth is this likely to be?
Q2: Is it sufficient to earth via conduit, or should all 3 CUs also be cross connected & attached to the electricity board earth -it would seem safer in principal?
Q3: We are in the process of having a bathroom fitted & the plumber has laid (in part anyway so far) the cross bonding earth connections -will this go to the electricity board earth or the (one of!) CU units -does it even matter?
Q4: I thought that there was supposed to be a single switch off point (or is this a recent change in regs), or is it ok to have to shut off 3 switches to close off all power?
For info my house is in suburban surrey & was built in 1936. It has clearly been rewired as all cabling is t&e except for one of the ligting circuits which appears to be good similar age twin core (i.e. pvc) but uses a separate earth cable & (metal) conduit for earthing. I presume the incoming mains is as originally installed in 1936.
Thanks for any help!