Torque Talk

[Marvo]

Long time no see and I hope you're all doing well.

I see that torque screwdrivers have become the height of fashion in the UK over the last couple of years. I wondered what general practice has been adopted regarding their use.

Are electricians expected to;
Have a torque screwdriver on site at all times?
Check torque of all terminations in CU's / DB's they open or just any new terminations they make?
Check the torque of all terminations in any accessories they open?

Also;
Is acceptable to do torque testing live in a CU (assuming a VDE screwdriver)? Is a risk assessment required for live torque testing?
If torque testing is performed in a DB/CU do you just check screws for tightness or do you loosen off all terminations first then re-torque to the correct figure to eliminate overtightened connections as well as loose ones?

 

[Dustydazzler]

I am tempted to use my 18v impact on the consumer unit tests on my next inspection

If questioned about the use of my 18v impact driver , my response will be 'well everyone else does it this way'

 

[pc1966]

Just had a reminder email from CEF about the coming calibration day in Dundee. Looked at the list and seems they don't offer torque driver cal as one of the services.

 

[timhoward]

Just had a reminder email from CEF about the coming calibration day in Dundee. Looked at the list and seems they don't offer torque driver cal as one of the services.

I'm starting to think that under the trade descriptions act they should stop calling them calibration days.
It's very rare to find anyone who is willing to actually adjust a device. My experience has been that they check against the manufacturers tolerances and it either passes or doesn't. If it doesn't they suggest sending it off for specialist repair.
I tried 3 different tester-days with that Megger 1552, on the 2nd two I told them upon arrive that "it isn't within spec, can you adjust it" and was told "No.". I'm looking forward to finding out whether my own efforts scrape through the system soon!

 

[ipf]

Just had a reminder email from CEF about the coming calibration day in Dundee. Looked at the list and seems they don't offer torque driver cal as one of the services.

Do they do 18v impact driver cal's?

 

[Dustydazzler]

Do they do 18v impact driver cal's?

This gezzer has mastered his own Cal test

 

[nicebutdim]

This gezzer has mastered his own Cal test

AvE has carried out some extensive tests on all manner of power tools - none survive, but he'll tell you which will be last to fail (or be pulled apart and never successfully reassembled).

 

[Marvo]

Well I've had my new torque screwdriver for a couple of weeks, I wanted to use it as much as possible to see why it's such an emotive issue. Unfortunately I work on control centres, everything from populating and wiring new panels in our workshop to sitework on panels of all ages... some of which are very old.

The first thing I noticed was very few components over a year or two old had a torque spec readily available for their terminations. Some maunfacturers were better than others, most of the Allen Bradley items had a spec if you were willing to comb through the individual spec sheets but much of the Indian, Chinese, Taiwanese or even USA manufactured items had no termination torque spec available whatsoever.

Second thing I noticed is how much work it is to torque check even a small control panel. Lack of spec aside, just the process of loosening all terminations and resetting them with a torque driver is helluva time consuming with the constant readjustment and changing of screwdriver tips. I did one very small panel, probably 5 or 6 years old that consisted of 9 or maybe 10 contactors and relays, a timer, a current relay and a few circuit breakers, a dozen pilot lights and maybe 25 DIN rail terminals and it took me over an hour. It was the first and last panel I did.

I could see their advantage in use for a domestic sparky working on new installs or CU changes or in a manufacturing environment. For existing installations I think with losening and retorquing they're not practical and just to retorque without loosening there's better, safer and more convenient alternatives to find poor connections such as careful visual inspection and thermal cameras.