Obvious departures from the regulations at first glance at a new consumer unit.

What is non compliant with an arrangement of two lighting circuits on one DP rcd and two socket circuits on another DP RCD?

This is a simple 4 way consumer unit.

So a fault causes inconvenience does it? You balance the inconvenience to the benefit of fault protection. Usually, then the fault is dealt with.

I am familiar with the common practice of mix and match lights and sockets across two RCDs. The dual RCD board is mass produced as an economical means to an end to accommodate whole RCD protection from the 17th onwards. The mix and match arrangement was in some literature, simply a diagram, produced by one of the consumer unit manufacturer's, Crabtree possibly, I cannot recall, but it seems to have been adopted as some kind of rule, which it is not.

You can install how you like, both ways are "compliant" , but one, when you consider what you are trying to achieve is less "compliant" than the other, if your concern is danger, pretty much the same, but to a far lesser degree, if it is also "inconvenience".

I would go with the risk of danger, primarily, rather than inconvenience, in the event of a fault, as a starting point. Historically, one of the "danger" aspects put forward by the Clubs was darkness and falling down stairs due to all circuits being one one RCD. Some alleviated that by having an emergency light fitting in some position or another. That was a choice. In some instances it was probably a good idea, in other cases it was not relevant. But it is horses for course's.

All those of you out there doing electrical maintainance for reward for ten or 20 years or more will know what type of circuit, 99.99% of the time, is going to operate an RCD in a manner that people will refer to as "inconvenient". It is a socket circuit with things and appliances on. With lighting circuits, you really are limited to furry friend nibbling of cables, water leaks into a class 2 light fitting or DIY drilling into walls and hitting the switch wires. It is not going to happen very often , if ever. But, if it did happen the 0.01% of the time, it is fixed quick, because you do not simply "fix it" by turning off the faulty appliance or un plugging the faulty equipment from the 13 amp socket.

So, if in your logic, you want to limit the danger of some lighting in a house going off because an RCD operates, then do not put it on the same RCD as a socket circuit.

I think that the builder is showing reasoned risk appreciation with this simple and effective layout of circuits. ?. The construction may be pants, by someones opinion, but the danger aspect has been dealt with.

Think back to split consumer units on a TN. One main switch, some lighting circuits on the non RCD protected side and all sockets and cooker on the solitary DP 30mA RCD side. These lighting circuits were independent of the socket circuits or cooker circuits having an earth fault and operating the RCD. The builders configuration is a progression, in common parlance, from 16th Edition Boards to 17th Edition Boards.


I know what I have said above will set off much gnashing of teeth. But you do not have to go with the crowd. An electrician can be their own person. You do not have to accept all that is told to you as fact and that this such and such defined way is the only way that is "allowed". Even the most simple job is "designed" as you go as you decide as a best fit to BS7671, but be careful when using terms such as danger and inconvenience to substantiate a particular way of doing things that does, when put to statistical test, significantly increases the risk of danger. There is not a one size fits all "design" and please do not say that it is now a "rule" every circuit has to have its own independent RCBO.


To throw into the mix.

I will quite happily put out there that I have installed many tens of consumer units in that configuration. They even have building reg notification. WOW! At a guess, over the last 12 years or so , at least 4 or 5 of these have been shown at an annual assessment and not even a raised eyebrow. WOW WOW!!!!!


Do not believe all the Badgers Tails that are going about.

What is non compliant with an arrangement of two lighting circuits on one DP rcd and two socket circuits on another DP RCD?

This is a simple 4 way consumer unit.

So a fault causes inconvenience does it? You balance the inconvenience to the benefit of fault protection. Usually, then the fault is dealt with.

I am familiar with the common practice of mix and match lights and sockets across two RCDs. The dual RCD board is mass produced as an economical means to an end to accommodate whole RCD protection from the 17th onwards. The mix and match arrangement was in some literature, simply a diagram, produced by one of the consumer unit manufacturer's, Crabtree possibly, I cannot recall, but it seems to have been adopted as some kind of rule, which it is not.

You can install how you like, both ways are "compliant" , but one, when you consider what you are trying to achieve is less "compliant" than the other, if your concern is danger, pretty much the same, but to a far lesser degree, if it is also "inconvenience".

I would go with the risk of danger, primarily, rather than inconvenience, in the event of a fault, as a starting point. Historically, one of the "danger" aspects put forward by the Clubs was darkness and falling down stairs due to all circuits being one one RCD. Some alleviated that by having an emergency light fitting in some position or another. That was a choice. In some instances it was probably a good idea, in other cases it was not relevant. But it is horses for course's.

All those of you out there doing electrical maintainance for reward for ten or 20 years or more will know what type of circuit, 99.99% of the time, is going to operate an RCD in a manner that people will refer to as "inconvenient". It is a socket circuit with things and appliances on. With lighting circuits, you really are limited to furry friend nibbling of cables, water leaks into a class 2 light fitting or DIY drilling into walls and hitting the switch wires. It is not going to happen very often , if ever. But, if it did happen the 0.01% of the time, it is fixed quick, because you do not simply "fix it" by turning off the faulty appliance or un plugging the faulty equipment from the 13 amp socket.

So, if in your logic, you want to limit the danger of some lighting in a house going off because an RCD operates, then do not put it on the same RCD as a socket circuit.

I think that the builder is showing reasoned risk appreciation with this simple and effective layout of circuits. ?. The construction may be pants, by someones opinion, but the danger aspect has been dealt with.

Think back to split consumer units on a TN. One main switch, some lighting circuits on the non RCD protected side and all sockets and cooker on the solitary DP 30mA RCD side. These lighting circuits were independent of the socket circuits or cooker circuits having an earth fault and operating the RCD. The builders configuration is a progression, in common parlance, from 16th Edition Boards to 17th Edition Boards.


I know what I have said above will set off much gnashing of teeth. But you do not have to go with the crowd. An electrician can be their own person. You do not have to accept all that is told to you as fact and that this such and such defined way is the only way that is "allowed". Even the most simple job is "designed" as you go as you decide as a best fit to BS7671, but be careful when using terms such as danger and inconvenience to substantiate a particular way of doing things that does, when put to statistical test, significantly increases the risk of danger. There is not a one size fits all "design" and please do not say that it is now a "rule" every circuit has to have its own independent RCBO.


To throw into the mix.

I will quite happily put out there that I have installed many tens of consumer units in that configuration. They even have building reg notification. WOW! At a guess, over the last 12 years or so , at least 4 or 5 of these have been shown at an annual assessment and not even a raised eyebrow. WOW WOW!!!!!


Do not believe all the Badgers Tails that are going about.