Dual RCD?
- Thread starter ml1936
- Start date
You still have to split the circuits to minimise disruption in the event of a fault
Cannot agree more, I am using RCBOs in every installation for the last 4 years.
RCBOs have a couple of issues.
Most RCBOs are only single pole, that means that if the neutral is lost upstream of them and hence floats up to live and then that neutral becomes exposed to touch somehow the RCBO cannot provide protection. It also means if they are used downstream of another RCD (say a 100ma time delay) they will not discriminate with it on neutral-earth faults. DP rcbos solve this issue but not all manufacturers make them and they tend to take up twice the space in the CU.
RCBOs as typicaly used on a domestic mean you still lose all sockets on a floor. Better than losing everything in the house but still far from ideal
Most RCBOs are only single pole, that means that if the neutral is lost upstream of them and hence floats up to live and then that neutral becomes exposed to touch somehow the RCBO cannot provide protection. It also means if they are used downstream of another RCD (say a 100ma time delay) they will not discriminate with it on neutral-earth faults. DP rcbos solve this issue but not all manufacturers make them and they tend to take up twice the space in the CU.
RCBOs as typicaly used on a domestic mean you still lose all sockets on a floor. Better than losing everything in the house but still far from ideal
- Joined
- 8 Feb 2008
- Messages
- 435
- Reaction score
- 20
- Country
I completely agree with plugwash about RCBOs. I would add that the reason you see them in table 41.3 is because some people have strong reservations about how that might perform if a 'heavy' fault current flows. Such a current can cause the supply voltage to collapse and RCBOs (being 'electronic' devices) need around 50 volts to work.
Now I am no expect on the way the French apply the very same IEC / CENELEC requirements that we do - but they seem to have no trouble accepting a 30 mA 'front end' RCD on installations with a floor area of up to 40 m². I could be wrong about that but its what I got off the Internet so it must be true
.
They must have forgotten to apply 314 or maybe they read it as it should be
. Still think of all those grannies in France now at risk of falling down stairs when the lights go out in their in their bedsits 
Now I am no expect on the way the French apply the very same IEC / CENELEC requirements that we do - but they seem to have no trouble accepting a 30 mA 'front end' RCD on installations with a floor area of up to 40 m². I could be wrong about that but its what I got off the Internet so it must be true
.They must have forgotten to apply 314 or maybe they read it as it should be
. Still think of all those grannies in France now at risk of falling down stairs when the lights go out in their in their bedsits 
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
