Afternoon folks,
We bought a 400 year old vicarage about 1 year ago now and were just starting to refurbish it, part of this involves a fair bit of joinery. As I don't get to get my hands dirty as much as Id like at work these days I'm building a small workshop so I can make a load of sash windows, a kitchen and some other furniture.
I've buried 40m of 3 core 10mm2 SWA cables at a depth not less than 600mm between our incoming supply and the location of the new workshop, as I had 30m of cable left over I've also buried a cable to a location where we will hopefully have a hot tub in the future (got to try and keep the wife happy).
I plan to split the meter tails and install a small CU along side the existing CU to protect the submain and then install a small DB locally to break out into the required circuits.
It seems to be normal practice to only provide over current but not earth leakage protection to the two sub mains at the supply side, is this correct and if so does this still stand with 18th edition?
I would if possible like to protect the submains with RCBOs and then protect individual circuits with RCBOs just to be belt and braces. I appreciate this leads to a race condition which may be unsafe or a nuisance.
1) Is there any benefit to fitting a 100mA RCBO to the cable given the guidance seems to be 30mA max for protection of life.
2) If I fit a 30mA RCBO to the supply end then 15/20mA RCBOs to the downstream DB am I likely to suffer from nuisance stripping with machinery?
3) Can you get any form of 30mA RCBO with a short time delay - I appreciate the main purpose of the RCD is to make the circuit safe as quickly as possible and this is obviously a little counter intuitive.
For info:
I believe the incoming supply was at one point TT but has since been converted to TN-C/PEN.
Cables have been installed by direct burial without use of ducting ect.
The workshop will likely require some form of three phase supply wither from a rotary convertor or VSD.
Apologies for what is probably bread and butter to you guys but its been a while since I've worked with onshore small power stuff.
Kind Regards
Dave
We bought a 400 year old vicarage about 1 year ago now and were just starting to refurbish it, part of this involves a fair bit of joinery. As I don't get to get my hands dirty as much as Id like at work these days I'm building a small workshop so I can make a load of sash windows, a kitchen and some other furniture.
I've buried 40m of 3 core 10mm2 SWA cables at a depth not less than 600mm between our incoming supply and the location of the new workshop, as I had 30m of cable left over I've also buried a cable to a location where we will hopefully have a hot tub in the future (got to try and keep the wife happy).
I plan to split the meter tails and install a small CU along side the existing CU to protect the submain and then install a small DB locally to break out into the required circuits.
It seems to be normal practice to only provide over current but not earth leakage protection to the two sub mains at the supply side, is this correct and if so does this still stand with 18th edition?
I would if possible like to protect the submains with RCBOs and then protect individual circuits with RCBOs just to be belt and braces. I appreciate this leads to a race condition which may be unsafe or a nuisance.
1) Is there any benefit to fitting a 100mA RCBO to the cable given the guidance seems to be 30mA max for protection of life.
2) If I fit a 30mA RCBO to the supply end then 15/20mA RCBOs to the downstream DB am I likely to suffer from nuisance stripping with machinery?
3) Can you get any form of 30mA RCBO with a short time delay - I appreciate the main purpose of the RCD is to make the circuit safe as quickly as possible and this is obviously a little counter intuitive.
For info:
I believe the incoming supply was at one point TT but has since been converted to TN-C/PEN.
Cables have been installed by direct burial without use of ducting ect.
The workshop will likely require some form of three phase supply wither from a rotary convertor or VSD.
Apologies for what is probably bread and butter to you guys but its been a while since I've worked with onshore small power stuff.
Kind Regards
Dave