O
omega750
Hi All,
First post on this forum, but I've been reading the great questions and answers for years, so I hope someone can help me out?
I've renovated a few houses in my time and done some of the basic wiring myself, but my latest 1940's house is a real project and needs a professional's attention. Unfortunately my usual electrician of choice is in hospital (no he didn't electrocute himself) so I have had to find another.
Overview
Old house, very poor 1940's wiring all needs replacing! From what I can tell there seem to be effectively 3 sub mains currently installed, all connected directly to DNO supply via a set of Henley Blocks.
The electrician has pointed out that there is no overload protection on the circuit in the summer house and garage which are more than 3m away from the DNO supply and connected via Henley Block. He has proposed the following setup, again all connected to DNO supply via existing (probably replaced) Henley Blocks.
Please bear in mind we are way past my level of expertise, but I am not sure how this is providing overload protection for the DNO supply as there is still only one set of tails to the meter and the DNO fuse behind that, presumably rated at 100A.
Whilst I see it protects the individual sub mains, what is preventing overload of the DNO supply other than its 100A fuse, given we have potential 100A + 80A + 60A draw via the Henley Blocks?
I was wondering if someone could just sanity check this proposal for me, hopefully it will just be a case of me not understanding overload protection otherwise I might need to consider finding myself another electrician?
Many thanks in advance.
Jason
EDIT: Garage has a car lift and some other machinery hence 80A CU
First post on this forum, but I've been reading the great questions and answers for years, so I hope someone can help me out?
I've renovated a few houses in my time and done some of the basic wiring myself, but my latest 1940's house is a real project and needs a professional's attention. Unfortunately my usual electrician of choice is in hospital (no he didn't electrocute himself) so I have had to find another.
Overview
Old house, very poor 1940's wiring all needs replacing! From what I can tell there seem to be effectively 3 sub mains currently installed, all connected directly to DNO supply via a set of Henley Blocks.
- Main CU (old fuse based unit)
- Summer House 10mm2 SWA to 60A MCB CU
- Garage 10mm2 SWA to 80A MCB CU
The electrician has pointed out that there is no overload protection on the circuit in the summer house and garage which are more than 3m away from the DNO supply and connected via Henley Block. He has proposed the following setup, again all connected to DNO supply via existing (probably replaced) Henley Blocks.
- Replace existing main fuse based CU with 100A MCB CU
- Install 1x Wylex 60A SF connect to 10mm2 SWA for Summer House, retain existing 60A MCB CU installed in Summer House
- Install 1x Wylex 80A SF connect to 10mm2 SWA for Garage, retain existing 80A MCB CU installed in Garage
Please bear in mind we are way past my level of expertise, but I am not sure how this is providing overload protection for the DNO supply as there is still only one set of tails to the meter and the DNO fuse behind that, presumably rated at 100A.
Whilst I see it protects the individual sub mains, what is preventing overload of the DNO supply other than its 100A fuse, given we have potential 100A + 80A + 60A draw via the Henley Blocks?
I was wondering if someone could just sanity check this proposal for me, hopefully it will just be a case of me not understanding overload protection otherwise I might need to consider finding myself another electrician?
Many thanks in advance.
Jason
EDIT: Garage has a car lift and some other machinery hence 80A CU
Last edited by a moderator:
