Failed calibration advise

Discussion in 'Electricians' Talk' started by Domesticsparky, Jan 14, 2022.

  1. Hi guys, so I've never had this before but today I was informed my torque screwdriver failed calibration in an epic style.....I.e.2.5Nm setting was actually torquing to about 1Nm........

    Little concerned as I have used this as my primary since September as I broke my old main one. I've done dozens of jobs where torque is important since then.....

    Rang Mr NIC and asked for advise regarding previous jobs and they basically said "Not sure but we'll get back to you"

    Now I don't know when this one broke.....could have been yesterday for all I know.

    Would you be inclined to go back and re torque customers I have been too....

    I'm concerned as it's not like it's 0.5Nm it's 1.5Nm difference.

    Any advise would be great.
  2. It sounds like you've got a conscience and your going to worry about it. If I were you I'd go to jobs in reverse order. If you find a recent job is torqued up ok then it's highly likely the earlier ones are ok.
  3. This is the thing, I'm sure technically I'm safe as the screwdriver was under a current cert.......but my conscience is telling me I need to check.......I guess I'm going to be extra busy next week haha
  4. I know what you mean. You are probably technically covered as it was callibrated. But by even putting the post on it shows you care and are going to lose sleep over it. Do recent jobs near home first and see if they are ok.
  5. Comlec

    Comlec Screwfix Select

    Damn. I thought a torque screwdriver was to show your assessor once a year along with your lock off kit. Now you come along and tell us we are supposed to use them - no wonder they break :)
  6. Tony Goddard

    Tony Goddard Screwfix Select

    Having been a registered spark 20 long years now working on commercial and domestic I can fairly say I've never owned or indeed used a torque screwdriver, nor been asked about it on the good old inspection visits. No one I work with has one to my knowledge.

    I have however had to tighten arcing connections on boards where apparently dilligent folks have used such an instrument so I'm none too impressed.

    Personally I wouldn't bother buying one, but I'm assuming they are not drastically expensive, in which case if I was required to at some point I'd be tempted to just chuck it and buy a new one every year rather than calibrating yet another item. Even if I owned one, I'd still want to go along the busbar checking with a proper, old fashioned driver! There is quite a lot wrong in theory relying on a torque device when comressing different sizes and sections of copper in a terminal, the process of tighten, the check later all connections and a gentle pull with long nose pliers is far more satisfactory. A terminal set to a given torque could fail pretty quickly, this week I went to look at a Havells main DB in a school, it had all been "torqued" but 10 of the 16 breakers were loose with sufficient damage to the busbars that the board will have to be re-built with new bars and many new breakers.

    In industry, for example aviation, where torque equipment is used it is routinely tested on calibration testers, daily or more often, (however when torquing a nut, say on a cylinder head, you are running it against a solid, smooth surface, pulling evenly on the stud, in a terminal you are clamping against an irregular shape (wire) made from a material that is in mechanical terms like play dough) - just as we are supposed to stick our two pole tester on a proving unit - I own a proving unit, but it has no batteries in, and TBH I couldn't tell you where it is!

    Edit - £60 + Vat, basically a consumable, might even get one to play with!
    Last edited: Jan 14, 2022
    seneca likes this.
  7. Tony Goddard

    Tony Goddard Screwfix Select

    You are now realising they are worth the membership fee - I'm a member of a CPS for two reasons
    1/ they process my notifications
    2/ I can use their logo

    Thats it!!
    Sparkielev likes this.
  8. MGW

    MGW Screwfix Select

    I used a torque spanner for years, it clicked at correct torque, but one could still feel how tight, I am sure I would realise if well out.

    Now the PAT tester was diffrent, it had go/no go lights no meter, sent for calibration, and it arrived back with certificate it seems traceable, and I would not have questioned the results.

    However decided to use computer software, which required a value, so asked what to do, and I don't know why I didn't think of it, look at certificate and enter better than figure on certificate, however slight problem, no figure entered.

    It seems the people I had given it to, subcontracted the calabration, so time dragged on until I made some threats, but I had returned software and used excel so could use replace command once I had the value.

    Next was could they have it to re-calabrate, so much for traceable, so they had it back, and found it was made when the pass level was lower, and could not be altered to comply with current regulations.

    So I had 1000 useless PAT testing records. I have never trusted calabration houses since, in the main a socket at work tested every morning then only one days work can be wrong, a one meg ohm resistor easy.

    We did same with torque wrench, 56 pound weight on a 6 inch bar or similar. Simply can't trust calabration houses.
    PhilSo likes this.
  9. Historically I have used the tug test or on more robust screws 3 uggas with the old impact.....but since taking on my daughter as my apprentice 2 years ago I've started to try and do things by the book........ Which is really hard when your 25 years on the job and set in your ways

    I'm sure she teaches me some days
  10. My old man was NIC EIC when he taught me and then I went to NAPIT, but soon realised they were a cowboy outfit so went back to being an approved contractor, but yer they never seem to help you when you ask for it
  11. spinlondon

    spinlondon Screwfix Select

    To my mind, the correct thing to do, would be to return to jobs in reverse date order and check the torque, until you find a job where the torque is correct.
  12. Tony Goddard

    Tony Goddard Screwfix Select

    Nice to hear of another female entering the trade, I've worked with two girl sparks, both were exceptionally neat in their work, particularly in consumer units. They also knew how to work that red and black thing with a smily face on, apparently it cleans up mess, but thats way above my paygrade!
    WillyEckerslike likes this.
  13. I noticed one of those appear on my van not long after she started.......I thought it was a I'm questioning it...

    My daughter is exceptionally the point it drives me crazy some days......but her boards are particularly neat......I must be teaching her right.....

    I do love the fact she takes after her old man, and I love seeing other trades faces when she rocks up to site with me......99% of everyone gives her banter and she takes it and gives it straight back....I've only had to stand in the way once luckily.....some smart plumber took a sexist jab at her body........didn't know I was her old man haha
    WillyEckerslike likes this.
  14. Teki

    Teki Screwfix Select

    Firstly, it's great that you are using a torque driver to check terminals as well as having it calibrated ;)

    For peace of mind, I would go back and re-check/record each of the terminals if practical.

    I was speaking to a few manufacturers of VDE torque drivers and you are supposed to recalibrate after a certain number of uses.

    The Wiha iTorque is handy as it has a digital display and a built-in counter to count the number of uses:

    However, after enquiring about recalibration costs I was told it would be cheaper just to buy a new torque driver!

    It would be interesting to know how much you paid for recalibration of your torque driver...
  15. £30 for a re cal and I paid £130 ish for a new screwdriver I think. Get it calibrated yearly
  16. The Happy Builder

    The Happy Builder Screwfix Select

    It does seem like a noticeable difference.
  17. elecstick

    elecstick Member

    There is one major problem in torqueing any connection, how do you ensure the surfaces are perfectly flat and parallel to each other, before torqueing. To better explain I'll give an example from a commercial incident. A 1000A breaker fitted over the w/e, monday afternoon smoke reported and paint being burnt on side of switch board. Removed side panel and top breaker terminals are glowing red hot. Later determined copper bus bars inaccurately formed so only one edge was touching the breaker terminal with a 2 or 3 mm gap on the other side, and torque wrench not powerful enough to close the gap, and therefore gives a good reading.

    Is that why someone decided ccu's must be inflammable?
  18. The Happy Builder

    The Happy Builder Screwfix Select

    Some consumer unit manufacturers crimp the ends of the internal tails into a square section, if these are then secured across their corners it doesn’t take much movement to twist them around allowing them to become completely loose.
  19. elecstick

    elecstick Member

    In post #17, I mistakenly used the word "inflammable" when I should have said "nonflammable", it gives a whole new meaning
    Teki likes this.
  20. I know what you mean, however I also know from a lot of domestic work......and EICRs that even when torqued, once you loosen them to do a test you end up having to reterminate the end as the grub screw has crushed the copper to the point of the cable snapping. I think on the bigger stuff, like industrial and commercial you need to have your wits about you when making off the connection, but on 10mm T&E at worst in a CU the 1.5-2.5Nm crushes the copper so a decent contact is made.......

    I just think some days 2Nm on a single 1mm cable is far to much if you know what I mean

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