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Some differences in opinion regarding EIC records

Those of you who’ve been kind enough to discuss things with me in the past will know that I like to get to the bottom of why different sparkles choose different ways of doing things so that I have a large arsenal of tactics at my disposal and to make sure I’m doing what is best rather than just going through the motions.

I recently attended a little additional training, we went through a number of different scenarios and I was surprised that the trainer insisted we record things on an EIC in a way that I believed to be inaccurate. It made made me wonder how the fine people of the forum approach similar situations? I’ll list them below.

1) The first thing is that he insisted that where we find a 1361 type 2 DNO cut out fuse that we absolutely must record it as a BS 88-3, he said that the 1361 fuse had been renamed BS88-3 and their characteristics are exactly the same for both. Now I’m a time served sparkie and was taught all those years ago you write down what’s in front of you (if the DNO label says 1361 then that’s what you record). I was also once given a chart for fuse comparison a long time ago and it says that the 1361 type2  was not renamed it was replaced and that thier characteristics are slightly different, in particular one has a 16.5KW breaking capacity and the other a 33KW capacity. Was I just taught to keep inaccurate records? I can’t see any danger in this but still it didn’t seem right.

2) The second is how one would record the supply characteristics and details at the origin. The scenario was the creation of a TT island where it is not preferable to export PME/TNCS outside for either an electric vehicle charger or shed and where an additional consumer supplied via an MCB in the original consumer unit is installed to facilitate this.. Again back in the day I was taught to record what you see. If it’s TNCS at the origin of supply you record that and it’s Ze, in the description of the installation you would indicate that you have separated the TNCS earthing and created a separated TT installation, and that the RA of the Ze of the separated system be recorded on the schedule of test results with the distribution board details. What the trainer insisted on is that the TNCS system should be totally ignored on the records and only details of the the TT system should be recorded on the particulars and supply characteristics section. This didn’t go down well with me as I would want anyone reading my EIC to fully understand that the main installation is connected to the PME network and that it and it’s bonding should be kept entirely separate from the TT system. What particularly bothered me is that having made us fill out a mock EIC (based on mock up on a test wall) with no mention of the TNCS/PME aspect we were then expected to record confirmation of equipotential bonding arrangement to gas and water on this EIC which by rights was not connected to the TT system at all. This really seemed bizarre to me. How do others make these records where a TT system is separated from a TNCS installation?

3) The last thing that irritated me is I was questioned in depth as to why I had recorded max permissible Zs on a TT circuit as 1667Ω instead of the figure from table 41.3 for the over current device. I had to very carefully explain that as the distribution board supplying circuit was part of a TT system where Ze far exceeds max Zs figures in table 41.3 and thus the 30mA RCD was providing both fault and additional protection, and that I felt anyone qualified to be looking at my schedule of test results would note that the R1+R2 value was a mere 0.01Ω and should be able to determine (without additional notes being made) that the circuit was not a sufficient length to require further consideration in terms of disconnection times or voltage drop. Personally I think it’s a bit pedantic and that any genuine sparks would get it either way.

Any way, I thought it’s a worthy discussion as I feel our aim with keeping records is to allow those who come after us to quickly determine our design decisions and without inspections determine the precise situation on site, possibly in advance before a site visit.

still running freely.

  • That's an interesting point John, he must have said you must cut the seal and look at the fuse. Not exactly legal that, must be a (minor) criminal?

  • Your instructor is wrong. BS 1361 fuses are not the same as BS88-3 fuses as they have different maximum fault current ratings.

    And, if you look in OSG, different max measured earth fault loop impedance for the same ratings.

  • It was a mix of very informative and entertaining and chuffing moronic and cringe worthy, at one point extra content was added at the cost of not covering everything advertised as being part of the course. Certain aspects were thoroughly covered and with good humour, other important questions were not answered or received responses along the lines of “you’re supposed to be qualified so I’m not answering that. Although I learnt a lot by the end I was so stressed I wasn’t able to recall things I’ve known for years and put into practice daily. I have today spent the afternoon sorting fact from opinion and opinion from the straight up wrong.

  • David

    Not to mention the dangers of pulling a fuse from an ancient fuse carrier noting that the DNO operatives have to put on anti flash PPE before doing so.

  • I assume you are going to give up teaching too? We have been sussed by Mike!

  • now I think you and others on here are hopefully examples of folk who actually do understand - so don't deliberately take my slightly provocative stance the wrong way !!  

    I just wish more  folk would do more than parrot the party line sometimes, and actually ask if the course material is credible. If it isn't it is the course that needs to change, not to expect the students to suspend their belief to assure a pass.

    Mike.

  • I'm sorry about that IronF, and something as simple as car chargers! The world is very complex in so many ways, yet we all are assumed to need to pay for classes to keep us on track, although what they teach is probably simple or wrong. I wonder what they said about RCDs and supplies, was that OK? Please don't be confused, in reality things change fairly slowly, and rarely are they completely reversed, BS7671 included. Charger arrangements are simple and the IET guidance note contains everything you need to know.

  • Though for at least one smart meter fitter in an SSE area, ungloved hands, shorts and a T-shirt seemed to be adequate, perhaps their training is not the same as the DNO. 

    Of course he may have set fire to the T-shirt since I last saw him, and I hope that his primeval urge to pull like a gorilla  is moderated on older installations where there is a sporting chance of the screws tearing out of a failing back board and the head parting company from the PILC cable... which is when that PPE would really justify the investment. The let through of the substation fuse is not to be sniffed at - in some cases the house service cable fails  first - the DNO chaps call that a "blow to clear" fault round here apparently.

    If the fuse moves freely and the carrier is well attached so it does not budge on the back board it is not really the same risk so perhaps in some cases the attitude is OK, but I was a bit surprised for someone who presumably rolls the dice and takes that risk several times a day.

    Mike.

  • With regards to RCDs and most of the theory and application of BS7671 and code of practice I think we were instructed well, my issues were mostly with regards to certification and documentation…. And that the actual test rigs were blatantly non compliant.

  • If anyone is ever thinking of building a better demo rig, it is still possible to do things in quite in a small space by using  opposite sides of a partition wall to put things closer but still 2m out of reach, as the user then has to walk round the wall.  and cannot touch both sides at once. It still is not realistic of course, but by writing 'indoors' and 'outdoors' on the 2 sides it does make it clearer, and avoids encouraging   impossible habits, like measurements between an indoor earth and an outside live, and makes realistic errors like 'oh dear I have left my meter leads in the other place and have to go back' a reality. Better to get the habit early than learning  after climbing to the top of scaffolding or an antenna mast to find the pliers and that special test adapter are still on the front seat of the van that now looks so small down there. (not that that sort of thing ever happens in the day job oh nooo Lying face)
    Mike.