The Value of R.C.D.s

whjohnson: 
Look at it like this Zoom - if a BS3036/BS3871/BS60898 device disconnects within 0.4 seconds then yes RCDs are nice to have but are they necessary?

Another way of looking at it given your car brakes analogy.

Fully functional braking system? Yup, that works fine.

Fully functional braking system with ABS? Also fine, but the absence of ABS in your braking system does not mean that your conventional brake set-up won't stop you.

Agreed!

What's this obsession with RCDs all of a sudden? We have talked about a 7% failure rate often enough and I think that reliance upon them is dangerous.

A properly built installation supplying properly maintained appliances does not need them.

The real question should be, “If I get a shock, will I let go or not?”

If Mrs P fails to mention that the flex of her smoothing iron has become worn, and then touches it, she will get a belt, but is unlikely to be gripping the flex. By contrast, if my lathe became unearthed, and a fault developed between line and the machine, I could be in bother because I might have hold of the saddle wheel. ADS won't operate in the case of the iron, but because the lathe is well maintained; first, it is unlikely to develop a fault; and second, if it does, ADS will operate.

Concerning car brakes: I have two cars which date back to 1930. The brakes are good enough, but I like to keep my distance from the car in front. I do not need ABS 'cos I know how to brake safely.

ETA: I deliberately did not put an RCD on my garage lighting circuit - it was installed right at the end of 17th Edn. The LED luminaires will not need to be relamped and they are well out of reach. How could anybody possibly get a shock off them?

(We could get into all manner of modern safety equipment in cars, but this not the correct forum.)

whjohnson: 
Look at it like this Zoom - if a BS3036/BS3871/BS60898 device disconnects within 0.4 seconds then yes RCDs are nice to have but are they necessary?

Another way of looking at it given your car brakes analogy.

Fully functional braking system? Yup, that works fine.

Fully functional braking system with ABS? Also fine, but the absence of ABS in your braking system does not mean that your conventional brake set-up won't stop you.

Agreed!

What's this obsession with RCDs all of a sudden? We have talked about a 7% failure rate often enough and I think that reliance upon them is dangerous.

A properly built installation supplying properly maintained appliances does not need them.

The real question should be, “If I get a shock, will I let go or not?”

If Mrs P fails to mention that the flex of her smoothing iron has become worn, and then touches it, she will get a belt, but is unlikely to be gripping the flex. By contrast, if my lathe became unearthed, and a fault developed between line and the machine, I could be in bother because I might have hold of the saddle wheel. ADS won't operate in the case of the iron, but because the lathe is well maintained; first, it is unlikely to develop a fault; and second, if it does, ADS will operate.

Concerning car brakes: I have two cars which date back to 1930. The brakes are good enough, but I like to keep my distance from the car in front. I do not need ABS 'cos I know how to brake safely.

ETA: I deliberately did not put an RCD on my garage lighting circuit - it was installed right at the end of 17th Edn. The LED luminaires will not need to be relamped and they are well out of reach. How could anybody possibly get a shock off them?

(We could get into all manner of modern safety equipment in cars, but this not the correct forum.)