The OP mentioned separate upstairs and downstairs light circuits. It's possible that the landing light might have "borrowed" the neutral from downstairs. If so this would need to be rectified before RCBO's could be used for these two circuits.
They don't necessarily, although some do have one.
The additional earth connection allows the RCD section to trip on additional fault scenarios that would not otherwise be detected.
RCDs greatly shorten shock duration of L-E shocks. They don't act on L-N shocks. Someone going to hospital because they got scared doesn't mean they're injured.
NT
not a bit. The standard survey phrase is you should get everything checked, which people normally don't do. If they're fool enough to do so, the very predictable outcome for most houses is it doesn't meet all latest regs. The y're none the wiser, but have parted with money at the time they can least afford it.
NT
Would the residual current breaker still work on a PME system where the incoming gas and water pipes were plastic?
Where would such an installation be getting its earth from in the event of a lost neutral?
A single RCD is moderately likely to not even work.
Surveys say get it checked regardless. A buyer that understands RCDs - few do - is one that can do the job themselves if they want.
Work out the cost & size of risk reduction. Compare with other options. The benefit per pound is far from top of the list.
NT
About the same as the chance of winning the lottery (give or take a factor of 10), yet many people buy lottery tickets.
If you simply want to make it more saleable, you could perhaps put a dummy new-style fuse box in a prominent position, and lock the cupboard with the real one in. :)
I bet Brian could do that with no problem. I bet you and I could do it blindfolded it we tried, I never have!
I've re spooled plenty of 35mm cassettes using a changing bag, and loaded various film sizes into the spiral if a developing tank in complete darkness.
I'm not suggesting for a moment that a sighted person in the dark equates to a blind person. That would indeed be arrogant.
More than likely - but familiarity is the key (and knowing what you are trying to achieve)
For an unskilled user attempting to identify the failed fuse, locate the right rating of spare fuse wire, effecting the replacement and then getting the fuse back into the CU - all in the dark, when you have never even bother looking at the fuse box in the past, is quite a "big ask"! Especially when compared to finding which MCB has tripped and flipping the switch.
Indeed, same here.
I always have a small pen knife in my pocket with a screwdriver that would be adequate to rewire a wylex fuse as well. I suspect I am in the minority though when it comes to preparedness for fuse re-wiring ;-)
I would expect a sighted person in the dark to perform substantially less well than a blind one.
Indeed - there are a few potential problems to crawl out of the woodwork. Probably worth anyone thinking o doing their own CU swap, having a read through of:
True, but the failure rate is not high enough to make that relevant I would say. (IIRC, 15% of those that have never been tested may fail to operate when they should - but that sill leaves 75% that will work and potentially prevent an injury)
Indeed. Hence my comment about it not being something that will help "sell" a house.
If your only criterion is avoidance of death due to electrocution, then the argument is plausible, since from a statistical point of view you may as well ignore the risk of death - its low enough to be insignificant.
None of that however diminishes the effectiveness of a RCD at preventing shock injury - the occurrences of which are commonplace rather than rare. (100's K of hospital admissions per year)
You jest, but I have seen similar...
One place which had been "fully rewired", actually had nice new sockets and light switches etc in conspicuous places, and shiny new CU. Its only when you looked closely you realised the nice new lengths of T&E exiting the CU went all of two feet before being joined back onto the old rubber insulated cables under the floor, and that most of the sockets were not even wired up!
I am not sure that makes sense... What is a L-E or L-N "shock"?
(or do you mean that a shock resulting from simultaneous connection between L & N, while completely isolated from any independent earth contact?)
It does if they now have cardiac arrhythmia...
I used to have a Wylex CU with the old style push button retrofit MCBs.
The face of the cover had been removed so it just formed a frame around the breakers. I don't remember if the original cover had been modified, or if it was a special item supplied with the MCBs
You would need to refer to the manufacturers notes for the actual set of conditions that are detectable by any given RCBO - they don't all work the same.
Loss of neutral may be one (although of little relevance for anyone on a TN supply in reality). It may also include things like detection of supply polarity reversal (more uncommon), or the ability to detect a N to E short in the absence of any current flow in the circuit.
Known as "Going equipped, in some circles ;-)
That was my intended inference.
I don't see that as a failure rate, just additional work to be done to rectify the earth leakage faults that may have unknowingly have been present for decades.
Not that I'm saying a whole house RCD was ever the ideal solution.
...Nothing another ZAP won't cure (allegedly).
Its main blade is about an inch long - I could do you more damage with a hard stare! ;-)
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