The Value of R.C.D.s

Please scroll down to the electrocuted people reports.

Do Landlords Need To Fit RCDs? Latest 2020 Regulations (electricblu.co.uk)

Z.

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Coroner and family call for better legislation on landlords after university lecturer dies of electrocution in rented Gloucestershire home - Gloucestershire Live

Z.

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.

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.)

You might be very thankful of an RCD when you pick up the lawn mower cable you’ve just sliced in half. I wonder why this was put into the 16th edition way back in 1992, could be the large number of shocks received in garden accidents by any chance?  RCDs in a domestic environment are always a good idea to protect against peoples poor judgments. 

A RCD can be a life saver, that is not in doubt, and given their cheapness these days it is hard to justify not fitting one - if only it were that easy.

3036 board so one in tails? Well yes, but hang on! The DNO will charge you the thick end of two hundred quid for a 5 minute isolator fit before you can do that.

Ok, a new consumer unit then? Same problem, but also now compounded by the fact that you have to pay the council (although in reality they are not the least interested) to notify it.

You can see why a fifteen quid 100A rated double pole life saver is not fitted as often as we might like.

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?

 

Will an OCPD disconnect within that time if someone touches a live conductor from a severed flex? (Lawnmower often quoted, but vacuum cleaner, pet or other accidental damage can also result in the same.)?

Answer … NO

The requirements in BS 7671 are for additional protection to be provided (411.3.3, 411.3.4), not fault protection. In fact, additional protection is supposed to operate if fault protection fails (as well as basic protection)

The distinction is important, because of the wording in 415.1.1:

415.1 Additional protection:RCDs
415.1.1 The use of RCDs with a rated residual operating current not exceeding 30 mA is recognized in AC systems as additional protection in the event of failure of the provision for basic protection and/or the provision for fault protection or carelessness by users.

(See underlines)

Basic protection might effectively fail for many reasons, not just direct “damage” - perhaps temporarily for example due to spilling water (or wine/beer/vodka etc.) on an appliance or extension lead, and being fortunate enough for this not to operate the OCPD …

Not flagging lack of additional protection by RCD, at least for the serious attention of the installation owner, I think puts the inspector in a difficult position.
 

Isolator cost really depends who you buy your electricity off some are cheaper than others so might be worth swapping provider. Also try getting one fitted if you have a smart meter installed. Probably cheapest to use someone who is Part P certified. 

 

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.

Yes your old inefficient braking system may stop you eventually, but perhaps after you have just run over the child in the road.

Z.

 

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.

 

Are you always in control Chris? Sometimes the unexpected happens and then we need all the help that we can get. This is especially helpful if it is automatic and swift in operation.

I recommend R.C.D.s in most cases.

Z.