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Eaton Glasgow Screw Torque

Will Elec

Hi all,

Just installing a glasgow 104gc switch disconnector. Instructions state 10Nm for terminals, so get torquing and the first screw breaks! As this is a TP+SN unit there is no netural bar but the instructions state 3Nm for neutral, so torque all other terminals to 3Nm and no problem!

Phoned Eaton technical and they insist that the terminals should be 10Nm - which for a small tinned brass flat head screw seems excessive! All the Schneider gear using similiar terminals I have fitted seems to be 3.5Nm and they have a far better combination pozi head.

Anyway, would appreciate some thoughts on this. I must admit I'm happy with 3Nm on the terminals but the regs say to follow the manufactures guidance....

Thanks

Parents
  • 0

    I have experienced exactly the same problem, but with a 63 A unit.

    The flat bit on my wrench could have had a better profile and it tended to chamble the slots. I had to replace them with hex drive grub screws.

    One also has to be careful not to damage the bakelite.

    I was surprised to find this problem given that the Glasgow devices are otherwise very well made.

  • 0 in reply to Chris Pearson

    Could the issue be that it's a 5/16 inch screw - so the metric slotted screwdriver bits are 'wrong' ?

  • 0 in reply to gkenyon

    It will depend slightly on 5/16 by what thread form, but in that leaflet it seems to attract the same 10Nm torque as the M8s, despite being a touch smaller.  Now in tables I have here, M8 in brass with 63% copper is listed as absolute max 9Nm while  10Nm is in comfortably in the middle of the range for steels. Now of  course it may not be that exact brass, but it is clearly sailing towards the top end of the possible in terms of stripping, let alone head shear- I do wonder if the 'steel' figure has been picked up in error when the datasheet was written.
    Mike

  • 0 in reply to mapj1

    I can confirm they are indeed M8 not 5/16, something tells me that the instructions have been repurposed from older units (made in England with better components!) and not be updated. Eaton are sending more screws but as you say Chris some M8 grub screws would be far more appropriate if the 10Nm is to applied

  • 0 in reply to Will Elec
    Will Elec said:
    made in England with better components!)

    Or made for USA market ... 5/16 is a common US thread size and Eaton sell switchgear there.

  • 0 in reply to gkenyon

    I may have started with my left-handed screwdriver by mistake. Wink Definitely M8 x 1.25 ≈ 20 tpi, which does not tally with any of 5/16 UNF/UNC/BSF/BSW.

    The problem is that so many screwdrivers have faces which are not parallel so they never really fit even when the thickness and width are about right.

    As far as I can tell, my original screws are stainless steel and not brass. Certainly the replacements are.

Reply
  • 0 in reply to gkenyon

    I may have started with my left-handed screwdriver by mistake. Wink Definitely M8 x 1.25 ≈ 20 tpi, which does not tally with any of 5/16 UNF/UNC/BSF/BSW.

    The problem is that so many screwdrivers have faces which are not parallel so they never really fit even when the thickness and width are about right.

    As far as I can tell, my original screws are stainless steel and not brass. Certainly the replacements are.

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