I have a problem.... of my own making in overcoming RCD discrimination
My OH rents a building used as a nursery and she recently had a sizable wooden outbuilding installed as a kind of outside play classroom.
The owners told her they were okay for me to install electrics although not 17th (waiting for new employer to arrange 17th)
Had a choice of 2 1ph sub-main DBs, 1 was old MEM, and 1 was newer split load Hager with RCD protection on both sides.
Both easily had room for a sub mains cable to out-building, both physically and by calculation.
MEM board was a non starter due to parts unavailable, and building owner said no to changing the DB.
Was reluctant to use split load board due to the rcd tripping and taking out a mix of lights and power to other rooms which at certain times of the year pose a greater risk due to low light levels.
However, my only viable option was the split load for reasons above.
Decided on Contactum DB, via approx. 40m 3core 10mm armoured protected by Hagar 63a MCB.
Split circuits down into
1 standard 100a main switch
1 6a 30mA RCBO lighting (4 main lights)
1 6a 30mA RCBO Lighting (6 external LED floodlight)
2 16a 30MA RCBO for a single 2kw heater on each.
1 20a 30mA RCBO for 1 Radial (4 points)
Armoured cable was earthed both ends AND (Perhaps wastefully) also by 3rd core.
No Water or metal in with building so no bonding.
My electrical tools are kept at work which includes testers etc. which I can get during next week but after doing the basic sub-main cable install today, using my personal multi-meter, did a basic continuity test and turned on.
Basic tests done, put in a quick radial socket to provide a light to finish trunking, wiring and later testing.
Pressed the test button on RCBO for temp radial and damn RCD in hagar DB went out.
Was always aware of risk running off splitload RCD protected DB but hoped I would be one of the lucky ones and the RCBO would trip 1st. Wasn't just unlucky as tried 4 times with same result.
Any suggestions on how to overcome this with limited expense that would comply with the 17th.
My OH rents a building used as a nursery and she recently had a sizable wooden outbuilding installed as a kind of outside play classroom.
The owners told her they were okay for me to install electrics although not 17th (waiting for new employer to arrange 17th)
Had a choice of 2 1ph sub-main DBs, 1 was old MEM, and 1 was newer split load Hager with RCD protection on both sides.
Both easily had room for a sub mains cable to out-building, both physically and by calculation.
MEM board was a non starter due to parts unavailable, and building owner said no to changing the DB.
Was reluctant to use split load board due to the rcd tripping and taking out a mix of lights and power to other rooms which at certain times of the year pose a greater risk due to low light levels.
However, my only viable option was the split load for reasons above.
Decided on Contactum DB, via approx. 40m 3core 10mm armoured protected by Hagar 63a MCB.
Split circuits down into
1 standard 100a main switch
1 6a 30mA RCBO lighting (4 main lights)
1 6a 30mA RCBO Lighting (6 external LED floodlight)
2 16a 30MA RCBO for a single 2kw heater on each.
1 20a 30mA RCBO for 1 Radial (4 points)
Armoured cable was earthed both ends AND (Perhaps wastefully) also by 3rd core.
No Water or metal in with building so no bonding.
My electrical tools are kept at work which includes testers etc. which I can get during next week but after doing the basic sub-main cable install today, using my personal multi-meter, did a basic continuity test and turned on.
Basic tests done, put in a quick radial socket to provide a light to finish trunking, wiring and later testing.
Pressed the test button on RCBO for temp radial and damn RCD in hagar DB went out.
Was always aware of risk running off splitload RCD protected DB but hoped I would be one of the lucky ones and the RCBO would trip 1st. Wasn't just unlucky as tried 4 times with same result.
Any suggestions on how to overcome this with limited expense that would comply with the 17th.
