17th Edition Question...Kind of!

Right a family friend want me to remove a consumer unit that is used as the heating board as it's all being done away as they are installing a combi boiler. So as the old domestic board is old fuses I'm going to replace it with the domestic board (mcb's). Now my question is do I have to make sure everything is up to regs once I do this, ie do I have to upgrade the main earth for the water to comply with new regs etc?

Yes, of course. That is only one small part of what you must do.

1. You must test existing supply for faults before you start as once the RCD is fitted faults are likely to trip this which would not have effected old system.
2. To do the tests you need meters able to test insulation with 500 volt and continuity with greater than 200 mA. Also you will need to test the RCD and the tester needs not only to test the milliamp required but also measure the time 40 ms can't be measured with a stop watch. Some things can be found by enquiry but using a loop impedance tester is far better.
3. Once completed all tests are repeated and recorded so likely you will need meters for more than one day especially if you find there is a fault.
4. Hire charges likely around £75 and to buy around £750 for meters.
5. Although you do not have Part P in Scotland you do it seems have a similar regulation.

So if you know what ELI etc is and have assess to meters then OK. But don't think it is easy. Even time served electricians have lost money hunting for faults after up-grading to RCD protection and some are hard to find.