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  1. P

    Calculation submain cables

    If it is TT then you can use the armour of any of them as CPC but will almost certainly need an up-front delay RCD at the sub-main feed point to allow disconnection on a fault. If TN-C-S then the bonding size of (typically) 10mm copper equivalent can be an issue for many SWA cables as it...
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    MCCB panel selection

    We are looking for a distribution board to provide 3 * 160A three-phase feeds, but they are basically redundant supply path options so max total is 160A as well. I had been looking at using a Hager MCCB panel (as we generally have been using their MCB DBs) but many of them are limited to 125A...
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    To pass or not to pass? that is the question

    Its not good, but as @westward10 already said it should be on RCD anyway. Totally aside from the impact on OCPD based ADS, extension leads are one of the things that most need RCD protection, either at the CU or in the form of an RCD plug, etc.
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    To pass or not to pass? that is the question

    While the ISITEE guide has limits, the reality is this is a production item that meets the various standards and is a damn sight safer than someone joining up 3 * 15m reels!
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    5 amp earth leakage?

    Not a reliable indication of a fault! What RCD characteristics (and also why is an incomer needed here)? Have you done a global L+N IR test to see if there is anything like a N-E fault?
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    5 amp earth leakage?

    Secondly how big is this installation? I.e. total current and types of loads used? Some things like large LCD displays or computer servers have a few mA or leakage anyway, so if your installation has a thousand of them you might have a simple answer!
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    5 amp earth leakage?

    Firstly how are you measuring the leakage? If you have a clamp ammeter around 3P+N then 5A is indeed quite a concern and probably indicates an insulation fault such as N-E short. However, if you are clamping the whole SWA cable, or the main earth conductor, then quite probably it is just PME...
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    Insulation resistance testing live conductors to earth

    There can be a few reasons for low L+N -> E readings: Connected equipment is leaking. By design, or just old/damp SPD are connected (but there you get a big difference between 250V where usually > 10M and 500V where usually < 0.1M) Cable has degraded or is very damp Accessories are damp/dusty...
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    UK some help with grouping of cables

    The point is you cannot allow a set of cables rated for 70C operation to be heated by those happy to run at 90C, so if you are looking at a section for that group, you should treat them all as if they were rated at the lowest temperature (e.g. 70C) when calculating and if you get an acceptable...
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    EICR coding of 521.8.1 violations (3P over 2 cables)

    Yes, last one ought to be C2 from BPG#4: Circuits with ineffective overcurrent protection (due, for example, to oversized fuse wire in rewireable fuses) However, it has been mentioned before that an "unsatisfactory" judgement could be based on a lot of poor C3 factors combined, rather than one...
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    Any advice on rewires?

    Good to hear. This forum is one of the worst sites of any I actually want to visit, but many other sites are still simply intolerable these days without some sort of blocking.
  12. P

    EICR coding of 521.8.1 violations (3P over 2 cables)

    I would be surprised if T&E is not able to deal with the 3P voltages as each core is rated to at least the nominal Uo to earth, and as that is between conductors they see nothing different. Even between the two lives on one side of the CPC in 3&E cable there is now double the thickness of...
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    EICR coding of 521.8.1 violations (3P over 2 cables)

    Maybe the Spanish Inquisition would do? It is odd that the vast majority of 3&E cable is used for two-way switching on SP circuits even though the cable is colour coded for use as a 3P+E cable.
  14. P

    EICR coding of 521.8.1 violations (3P over 2 cables)

    Another thread asked about two circuits sharing a common multi-core cable and regulation 521.8.1 was mentioned. A friend of mine has inherited the "opposite" issue of a 3P circuit spilt over two T&E runs. Yes, I know that is bizarre and not something you really would expect to meet. However...
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    2 circuits in one cable.

    Indeed. I am awaiting the EICR she has commissioned, I expect there to be more C1/C2s than anything else.
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    AM2- Clipping cables to tray with P clips?

    I always used the definition that a bolt was only part-threaded, while a machine screw was fully threaded. Normally a bolted fixing is held under compression so the threaded/un-threaded aspect ought not to alter lateral movement. If accurate alignment is needed you could attempt to use the...
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    2 circuits in one cable.

    It makes me feel uneasy as you could attempt to isolate one via the MCB and fine one of those cores is still live. Still, this has pointed out the regulation applicable another of my friend's inherited WTF cabling specials - a 1/4hp 3P fan fed from 2 * 1mm T&E (not even 3&E that at least was...
  18. P

    PAT testing courses

    Thanks for that suggestion for SELECT's virtual course, though I rather think it would be better to send him on an in-person course to get better feedback, maybe a bit of hands-on demonstrations, etc.
  19. P

    High Zs on a Campsite

    Just re-read the OP's post and it is an existing 5C SWA so presumably a 3P supply. For 40A and 150m you are seeing 6.6V drop or 1.65% of 400V 3P so it already meets a traditional rule-of-thumb 2% As it is 5C then the R1+R2 is basically the same (if you ignore the armour) so 0.165 ohm and with...
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    High Zs on a Campsite

    The other aspect to note about @Julie. suggestion is you are no longer depending on the supply MCB for fault protection, that is done by the delay RCD to meet < 5s distribution disconnection time, you can size the supply RCD for overload protection and so increase both the rating (e.g. to 50A)...
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