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MAIN SWITCH ON CONSUMER UNIT WITH TUNNEL TERMINALS AND 2 SCREWS

John Peckham
I did a periodic inspection today on a new installation with a 15 way metal LyX consumer unit. A nice job but no circuit chart, circuit breakers not marked up to show function and an open circuit on the neutral of the kitchen ring so outcome "unsatisfactory".


A 3 bed house recently completely refurbished with an electric boiler and electric cooking so quite a high potential maximum demand. I was very pleased to see the BS EN 60947-3 main switch had tunnel terminals with 2 clamping screws just like the good old days. Well done LyX nice to see and much better than cage clamps. The sparks even had a Whiska gland on the tails.As usual quite a few terminals need needed tightening including the main switch and more neutrals than lines. 


I found a defective RCD on a BG garage board last week. I was admiring the quality of the unit with the die cast cover and the IP rating but disappointed to find it did not trip on the instrument tests and also the test button. The RCDwas replaced and I have the defective unit to dissect when I have time. I will let you know how I get on.
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    John Peckham:

    I did a periodic inspection today on a new installation ...



    I still don't quite understand why it should not be a multi-signature EIC.



    I found a defective RCD on a BG garage board last week. I was admiring the quality of the unit with the die cast cover and the IP rating but disappointed to find it did not trip on the instrument tests and also the test button. The RCDwas replaced and I have the defective unit to dissect when I have time. I will let you know how I get on.

    Directly after my training, I installed one of those at home. Built like a brick privy! I had no problem at all with the RCD in contrast to the previous one which was dead as a dodo.
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    I still don't quite understand why it should not be a multi-signature EIC.



    Presumably a "regularization" situation where the original "designer" and "installer" were unable or unwilling to sign.


      - Andy.
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    John Peckham:

    As usual quite a few terminals need needed tightening including the main switch and more neutrals than lines.

     



    There will always be a relaxation of the screw friction with heat cycles but why should there be a difference in Lines and Neutrals, John?, unless psychological since both are usually at the same height and position etc., and subject to the same heat. Is a torque screwdriver in use?


    Jaymack

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    Maybe the difference is the lines are in cage clamps on MCBs, while N's are held in by a screw on N bar?
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    AJJewsbury:




    I still don't quite understand why it should not be a multi-signature EIC.



    Presumably a "regularization" situation where the original "designer" and "installer" were unable or unwilling to sign.


      - Andy.

     




    Presumably John hadn't been engaged as the Inspector in time to inspect cables before they were concealed etc. also, which would always have been required for initial verification.

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    Chris


    Yes and EICR for rental purposes. No doubt an un-registered person did the work or the EIC has been lost (that old chestnut) and not inspected by the Local authority because I would have done that and remembered the job.


    Jaymack


    One of the 1st slides on my inspecting and testing courses is a picture of a simple circuit with an ammeter in the line and one in the neutral and a voltmeter across the load with a switch in circuit. I ask when I close the switch will the ammeters read the same of differently, usually more than 1/2 the class will say the ammeter in the neutral will read less and when I ask why the common answer is the load absorbs the current or words to that effect. Most electricians seem to have that view as they will tighten line conductor termination screws unit they nearly shear the heads off and are less fussy about neutrals.
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    One grunt for N (and E), two grunts for L. ?
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    John Peckham‍ That's terrifying. How does one become an Electrician without a basic understanding of circuit theory?!
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    As long as you use a recently calibrated grunt and keep a record using you grunt check box!
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    The old skills such as correct tightening are not taught nowadays. You used to practice practice practice on bits of scrap until you could do it in your sleep. No need for a torque driver. Nowadays, in all walks of life, it`s about getting those bits of paper so you get people who can pass exams but not having a clue how to install. Sad innit?

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