Split consumer unit replacing one RCD with an switch/isolator if necessary

Hi thanks for the comments and opinions.

AFAIK you could simply swap an ordinary main switch for the second MCB.

That sounds like the simplest initial option giving new circuits RCD cover, and allowing the connection of potentially leaky 'old' circuits via a main switch without, say, one leaky circuit causing tripping out.

If you buy what is sold as a “Hi integrity consumer” you can have MCBs split between two RCDs and a couple of non-RCD ways that you can connect a potentially dangerous circuit with failed insulation to.

The  Hi-Integrity option seems a further refinement I hadn't thought of allowing an intermediate step between All-old-circuits-on-a-switch and All-old-circuits-on-a-RCD. As would use of RCBOs.

To do it for a customer really requires the electrician to get a written acknowledgment from the customer that there is a dangerous situation.

The customer does recognise this, and acknowledges this in an email I have.

Nearly all split load consumer units can be tricked to link out either or both RCDs, and they are the same form factor as the incoming switch,  but as noted to do so is not to current regs. Arguably it is a reasonable intermediate step, being no more dangerous than what was there before, you are OK so long as you don't go backwards in safety at any point.  

Having an "reasonable intermediate step" is one thing I wasn't certain of regarding wiring . In the auto-industry I've often given the aim for application of older products as "to be as safe as or safer than the existing item" - the existing item being an application already out there with an accepted safety-case. I do note you (mapj1) say "arguably" on this point, It would be useful to know if there is anything in the regulations on making an existing circuit safer then it was but perhaps not as safe as current regulations require.

The main aim of this question is to come up with a scheme whereby I can convince the customer to have RCD protection installed for the 'new' circuits with an eye to dealing with the old leaky circuits in the future. Thanks for the comments.

Jonathan

Hi thanks for the comments and opinions.

AFAIK you could simply swap an ordinary main switch for the second MCB.

That sounds like the simplest initial option giving new circuits RCD cover, and allowing the connection of potentially leaky 'old' circuits via a main switch without, say, one leaky circuit causing tripping out.

If you buy what is sold as a “Hi integrity consumer” you can have MCBs split between two RCDs and a couple of non-RCD ways that you can connect a potentially dangerous circuit with failed insulation to.

The  Hi-Integrity option seems a further refinement I hadn't thought of allowing an intermediate step between All-old-circuits-on-a-switch and All-old-circuits-on-a-RCD. As would use of RCBOs.

To do it for a customer really requires the electrician to get a written acknowledgment from the customer that there is a dangerous situation.

The customer does recognise this, and acknowledges this in an email I have.

Nearly all split load consumer units can be tricked to link out either or both RCDs, and they are the same form factor as the incoming switch,  but as noted to do so is not to current regs. Arguably it is a reasonable intermediate step, being no more dangerous than what was there before, you are OK so long as you don't go backwards in safety at any point.  

Having an "reasonable intermediate step" is one thing I wasn't certain of regarding wiring . In the auto-industry I've often given the aim for application of older products as "to be as safe as or safer than the existing item" - the existing item being an application already out there with an accepted safety-case. I do note you (mapj1) say "arguably" on this point, It would be useful to know if there is anything in the regulations on making an existing circuit safer then it was but perhaps not as safe as current regulations require.

The main aim of this question is to come up with a scheme whereby I can convince the customer to have RCD protection installed for the 'new' circuits with an eye to dealing with the old leaky circuits in the future. Thanks for the comments.

Jonathan