WHAT WOULD YOU DO?

" I was sat next to my ? on the settee last ? scrolling through the emojis and she asked what on ? I was doing, I replied I was ? through the choices of emoji on the IET discussion forum to reply to a post by JP she ? and said are there really emojis on the forum? Then ? again when I showed her the choice." 


?

What you ladies don’t know is that one of my brothers and his family lived about half a mile away from JP, some years ago there was a couple of forum get togethers and I drove my wife down to have a girls night out with her sister in law and nieces whilst I picked JP up and drove him to the forum get together.


My wife hasn’t actually met JP, but is fully aware of who he is and has a fair impression of what he is like from conversations after I have seen him, sometimes when I wasn’t expecting to, hence the raised eyebrow at trying the the emojis out replying to his post, that and that there are emojis in the first place and being unsure when it would be appropriate to use some of them.


My wife has met Bod aka  perspicacious a number of times, indeed I have seen him on out settee drinking tea and eating cake. It’s surprising how many people you can become acquainted with after a few years of kicking around this forum.


Andy

Is the wording of that note in the regs book supposed to inform us that when testing RCDs rated at 30 mA or less if we do a X1 RCD and it trips in 40 milliseconds or less then we don’t need to do the X5 test?


Some years ago I asked if we needed to do the X5 test on a 30 mA RCD if it tripped in 40 mS or less at X1 and the conclusion was that yes we do.


Andy

OK here is my decision making process.


The room contains a shower so the BS 7671 Part 1-6 General rules apply and is a special location so 701 applies in addition.


All circuits in the bathroom require 30mA RCD protection to comply with 701.415.2. That RCD is there for Additional Protection.


I was carrying out a Periodic Inspection and Test in compliance with Chapter 65. Chapter 65 does not prescribe any tests but says my inspection should be "supplemented by appropriate tests and measurements from Chapter 64". Interestingly 651.2 (vi) only requires me identify defects and non-complaisance's with BS 7671 "that may give rise to danger" so I don't have to record C3s but I do.


I go back in to Chapter 64 and look at regulation 643.8. This regulation required me to test RCDs for Additional Protection with an instrument complying with BS EN 61557-6. I use an instrument that complies with this standard which is calibrated annually and goes on my test box once a month. There is Note to 643.8. As you already know Notes to Regulations are not regulations in themselves but only supply guidance. This note says that the effectiveness of the RCD is deemed to have been verified if I test the RCD at x5 (150mA) or higher. So what is higher then, how a bout a couple of Amps that should get the sticky-est RCD to operate but what if it did not operate at 50mA? I my humble opinion this Regulation needs a serious re-write.


Then I look at Regulations in 643.7.1. This section relates to fault protection on TN and TT systems. My RCD is not provided for Fault Protection only Additional Protection. In this set of Regulations again an instrument complying with BS EN 61557-6 must be used to test RCDs. However the Notes to this Regulation refer me back to Table 3A in Appendix 3.  Now other than for Appendix 1 which is Normative all the other Appendices are Informative so are only there for guidance. Table 3A sets out the product standards for BS EN 61008 RCDs and BS EN 61009 RCBOs. My RCD does not trip in the set time (300ms) with a test current of 30mA and in fact does not trip at all. So I conclude the RCD is defective.


So to avoid the above being the first 5 lines of a fatal accident report and have been a frequent visitor to the witness box in the magistrates, Crown and County Courts over the last 30 years I have experienced lawyers trying to humiliate me in cross examination.


I then apply the "my mum" test. I know the RCD is defective. I know the occupant is a frail old, disabled lady. Would I be happy for my mum to stand in a shower in a pool of water able to touch the shower that has live parts inside a thin plastic box and the live parts connected to a 40A MCB. Answer no. So if it is not safe for my mum then it is not safe full stop.


 So my action was to switch off the RCD and the MCB supplying the shower. Advised the old lady not to use the shower and pointed out I have switched it off. Advised the warden who was off site at the time of what I had done. Called the maintenance electrician for the site and asked him to replace the RCD ASAP. Told him it was a Wylex 63A 30mA and he said he had one on the van and would replace the defective one that evening. I asked him to send me the defective RCD for my black museum and for some bench testing in my workshop.


I am fully signed up to the old saying that, " a clear conscience is a comfy pillow". 

Too true J.P. Too true. But all that book lernin' will give you a headache I rekkon.?. I have a pet saying. "If in doubt.......chuck it out."


Z.

I agree with you John. In fact I think amdt1. needs a bit of a proper "Engineers look" as there are many things which are not quite what one might like, as we have discussed before. Perhaps the makeup of JPEL/64 needs one or two more actual practitioners!

(Dear me * ?) - until this morning I had missed the full horror and true significance of the rather open ended phrase 'or higher' in that note.


It does actually  imply that even if it only just opens on the last ditch big red button 25A two wire loop test, then that may  be taken as indicating the RCD is OK, and no further RCD testing is required.  Given that quite a few 6A MCBs and RCBOs open on that test if you do it L-N as well, its not that great a test of the RCD function, is it ? Still it means the cowboys can check all ratings of RCD with the same test ?


Further tests at 30mA or whatever and then getting the thing  changed is of course the right thing to do.?


(* those who know me well enough can mentally substitute the phrase that I might have used;  but the automatic profanity  check would have rejected )

John, what would I do? It wouldn't satisfy my grand-daughter test, so it would have to be replaced. ?


Thank you for your thorough analysis, but what has changed since 17th+3?

• 651.2 was 621.2 - essentially the same

• 643.8 was 612.10 - the note is an addition, but read on!

• 643.7.1 was 612.8.1 - again the note referring to Table 3A is new, but the table is not and it isn't obvious why the table was there previously

• 415.1.1 used to refer to the max. operating time of 40 ms at 5 IΔn so in fact that is not new - it has simply been put elsewhere

• the generic schedule of test results has changed from two columns for IΔn and 5 IΔn to one unspecified column

Could it be that for additional protection, the max trip time at 5 IΔn is appropriate, but for ADS in a TT system, it is the max trip time at IΔn which is important?


Incidentally, BS61008 specifies a max break time of 40 ms at up to 500 A.

Chris


The changes relating to this requirement were the move of the 40ms at 150mA from Chapter 41 to Part 6. 


The big change I strongly object to is testing RCDs only at x5 or higher. The higher bit is just stupid! I have heard one manufacturer recommending a test at 250mA. What is the purpose of this test is it to get the RCD to trip? Or should it be a test the RCD at a potentially lethal current and verify it will disconnect the supply in a safe time.


Graham Kenyon posted a very good table on the old forum for testing of RCDS that I think should appear in the future AMD1 to the 18TH.


I note that the sad posts by Zoom of a double fatality concerning a shower and GB post of a fatality in rented premises could have been prevented by RCD protection.