You are right, a typical 16th edition "split load" CU would have one RCD protecting some or all of the socket circuits, and typically anything else not on the protected side. These are not what most would understand as a "whole house" RCD install though.
IME many of the "converted" whole house RCD installs are pre 16th edition (quite often long before 16th edition!). Often Wylex a BS 3036 re-wireable fuse boards, where they were upgraded with a front end RCD to feed the whole CU.
If an RCBO trips, does it tell you whether it's due to a leakage current or an overload?
There is often a window which shows a different colour if there's been an earth fault. eg the part marked (6) on this one turns blue:
The alternative is spending huge amounts of money, with lots of disruption, disproportionate to the number of lives saved.
<SNIP>Yes, Part P simply causes bodges - such as my conservatory electrics being an extension of the existing ring, with an FCU for the lighting ... when I have spare ways in the CU and a direct, underfloor route for cabling.
Only if it was a TT supply. RCDs were rare in the 80's, it was the early
90's before they became commercially available at a reasonable price here, when the 16th (1991) was introduced, was the first time they were generally used.For TN-S/TN-C-S supplies, it would have the main switch, with , generally, socket/shower circuits on the RCD, with lighting and others on the non-RCD side. It was called a 16th edition board then (1991 onward).
17th Edition,2008, pretty much put all circuits on RCDs, but on split RCDs, so 2 RCDs in the consumer unit.Before the 16th Edition, there could have been a VOELCB device upfront, which measures the voltage to earth. These are superceded, and should be replaced now, as they are nowhere near as safe as RCDs, and give a false sense of security, as they will not trip if a fault goes to earth via any other path other than the earth connection to the VOELCB.
When this bungalow was being modernised six years ago, including re-wiring and a new CU, I specified RCBO's on all the circuits. I have seven: two B6's for two lighting circuits, a B16 for the immersion heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen and garage, and sockets rest of the bungalow) and a B40 for the cooker.
My workshop had a Wylex fuse board - I changed the fuses for MCBs.
I've still got my copy of the 15th Edition, perhaps I should re-read it.
I think I have around 16 breakers in my CU :-(
If you want to be up to date:
Why do you think an RCD would save the day? All the hair driers I've seen are double insulated with no visible earth.
We're now getting into the stage where all sockets should be replaced with fused outlets.
Now that I agree with you.
Presumably a current flowing from the exposed live heating element through the nail file and the lady to earth would trip the RCD?
Without an RCD it would require enough live-side current to blow the fuse or trip the MCB, which is a lot less than a 30mA RCD earth fault. Perhaps shorting element windings would do it, whereas leakage from the live conductor might trip before the file had been inserted far enough to short anything.
Theo
We are told that a fuse had blown. And that it was a 'nasty belt'.
I would also wager that the lady was on an insulating surface such that the current to ground could have been well below 30mA and likely below 15mA.
I would say that the only advantage of a more modern system would have been a faster reacting MCB. Either way the likelihood of a "shorted live to earth" in a double insulated hair drier is remote.
Do hair dryers really count as double insulated? Whatever she did took the fuse out.
So you are implying a re-wire? Really extension bars should not get approval for sale if the distance from the earth pin to the closest side is less than the gap between the earth and live/neutral pins as this allows a plug to be inserted in a way which opens the shutters...
I wondered about that. I should have examined the dryer more closely. She admitted trying to clean it with a nail file .....
Dave
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be replaced by type A devices (which are said to be resistant to locking up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own RCD protected feed and this will have to be a type A device, but I'm not sure if all the others would need changing. Someone with knowledge of rev 18 will be along shortly to explain.
Parents 1956-built house (no cpc in lighting circuits) was upgraded like this).
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's normal requirement is just an isolator and a double-pole MCB in its own enclosure, with no need for an RCD or RCBO external to the charger itself; the cable was run inside the electricity box and then through the wall to the back of the charger, therefore there was no wiring regulations requirement for an RCD on that; if an external run or a shallow internal channel was required, the installer would have used cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and extra tails and preferred the cable straight into our existing CU. By using an RCBO rather than a double-pole MCB, I obtained the required overcurrent protection and double-pole isolation, while using only a single slot - the RCD part of the RCBO is not actually required at all.
Wiring Regulations are not retrospective - there's no need to have any RCDs or RCBOs on an older installation. Changes to that installation may require upgrades at the CU though.
Also some suggestion that an excess DC superimposed in the mains could affect an neighbour, if this blog is believable
Whilst “untidier”, having a separate enclosure and Henley blocks make it far easier to isolate vehicle charging power from a solar panel/battery/inverter set up.
It’s all too easy to end up draining your house battery into your car otherwise.
Tim
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