H
hightower
Morning all,
As the regulars know, I work in a school part-time (while sparking part-time), and I'm going to do a bit work for them - they need power dropping in for 11 PCs. No problem, 2 RFCs should do to share the leakage currents of the machines, bit of dado trunking round the room, RFC covers the additional earth return path needed, job's a good 'un.
What's more, there's a DB in the room too so the run is an absolute doddle. But where I need help is with finding a suitable RCBO for the board. It's a MEM 3-phase board, (see attachment), and the following ways are spare:
Y1 (but as you can see, the dual module of B1 sits in this space)
Y5 (but again, the dual module of R5 sits in this space)
R6
Y6 (protective device installed, but not in use)
B6
There-in lies my problem. If I'm to use these BS3871 devices I need four spare ways, and I only have three. So I've got two possible solutions:
1) Somebody suggests a single module RCBO that I can use in this board (opening the board up, there's not a lot of head space between the breakers and the enclosure, so really not sure this is a solution.
2) B5 is only feeding a solitary CCTV camera, it's wired in 2.5mm and on a 6A. I could drop this cable in with say, B4 - Alarm Spur in Corridor, or any number of 6A breakers feeding lights.
So I guess option 1 would be my preference, but does anybody see a problem with option 2 should option 1 not be feasible?
Also, a sub-question, just out of interest. Every lighting circuit from this board has 2.5mm down as the cable size - I'm guessing they've done this to account for voltage drop on longer runs. Question is, why have they wired the CCTV in 2.5mm too - it's literally 3m from the board.
View attachment 35354
As the regulars know, I work in a school part-time (while sparking part-time), and I'm going to do a bit work for them - they need power dropping in for 11 PCs. No problem, 2 RFCs should do to share the leakage currents of the machines, bit of dado trunking round the room, RFC covers the additional earth return path needed, job's a good 'un.
What's more, there's a DB in the room too so the run is an absolute doddle. But where I need help is with finding a suitable RCBO for the board. It's a MEM 3-phase board, (see attachment), and the following ways are spare:
Y1 (but as you can see, the dual module of B1 sits in this space)
Y5 (but again, the dual module of R5 sits in this space)
R6
Y6 (protective device installed, but not in use)
B6
There-in lies my problem. If I'm to use these BS3871 devices I need four spare ways, and I only have three. So I've got two possible solutions:
1) Somebody suggests a single module RCBO that I can use in this board (opening the board up, there's not a lot of head space between the breakers and the enclosure, so really not sure this is a solution.
2) B5 is only feeding a solitary CCTV camera, it's wired in 2.5mm and on a 6A. I could drop this cable in with say, B4 - Alarm Spur in Corridor, or any number of 6A breakers feeding lights.
So I guess option 1 would be my preference, but does anybody see a problem with option 2 should option 1 not be feasible?
Also, a sub-question, just out of interest. Every lighting circuit from this board has 2.5mm down as the cable size - I'm guessing they've done this to account for voltage drop on longer runs. Question is, why have they wired the CCTV in 2.5mm too - it's literally 3m from the board.
View attachment 35354
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