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?

 

[pc1966]

You should have it calibrated regularly already.

Or at the very least store it wound to minimum setting.

 

[Dustydazzler]

I'm all for the correct tightness in theory, it winds me up when colleagues use impact drivers to tighten (permanently weld) screw connections in CU's. I'd bet the correct, recommended torque, is less than normal wrist driver tightness.

If it becomes mandatory bureaucracy, how long until you need a calibration certificate for your torque screwdriver.

The amount of Sparks I see using their 18v impact to do a consumer unit change grinds my gears , that hammer impact action on all the connections can't be good for them. I have no idea how many NM the average Dewalt 18v Impact driver delivers but I bet its more than the desired torque needed for the average MCB or RCBO terminal.

Just looked at some of the MI and some 18v impact drivers can deliver up to 1800NM of Torque yet many Sparks think this is an acceptable tool to make CU connections

 

[mainline]

The amount of Sparks I see using their 18v impact to do a consumer unit change grinds my gears , that hammer impact action on all the connections can't be good for them. I have no idea how many NM the average Dewalt 18v Impact driver delivers but I bet its more than the desired torque needed for the average MCB or RCBO terminal.

Just looked at some of the MI and some 18v impact drivers can deliver up to 1800NM of Torque yet many Sparks think this is an acceptable tool to make CU connections

I haven't long bought a bosch go screwdriver, I've only used it to tighten up some kitchen doors so far

 

[Dustydazzler]

Is Setting your Torque screwdriver to the highest setting and using it as a normal screwdriver Bad for it ? Will months and months of it being set to the highest setting eventually mess with the Lower settings ?

 

[mainline]

Is Setting your Torque screwdriver to the highest setting and using it as a normal screwdriver Bad for it ? Will months and months of it being set to the highest setting eventually mess with the Lower settings ?

Yes

When storing a torque wrench for an extended period of time, always wind it down to the minimum scale setting and not to zero

 

[littlespark]

Is Setting your Torque screwdriver to the highest setting and using it as a normal screwdriver Bad for it ? Will months and months of it being set to the highest setting eventually mess with the Lower settings ?

Are you saying you’ve ran out of normal screwdrivers?

 

[Dustydazzler]

Are you saying you’ve ran out of normal screwdrivers?

Not at all , I love a Screwdriver and still have my old CK set and old WIha set in my every day carry bag

But I have 2 Vde torque sets that see the light of day maybe once a month and I have considered just ramping up to the highest torque and just using them as normal everyday drivers

 

[mainline]

Are you saying you’ve ran out of normal screwdrivers?

Using it as a screwdriver without going over the torque setting shouldn’t do much harm, but hitting the setting and continuing to tighten, I wouldn’t have thought would do it any good.
I must admit I alway go over terminations again manually with a normal driver at the same time as giving the cable a wriggle near where it terminates doing it that way I sleep better

 

[mainline]

Not at all , I love a Screwdriver and still have my old CK set and old WIha set in my every day carry bag

But I have 2 Vde torque sets that see the light of day maybe once a month and I have considered just ramping up to the highest torque and just using them as normal everyday drivers

It’s ok if you can afford to waste them
I keep the torque set and bits for just that.

At least I known the bits aren’t worn away when I come to use it

 

[Dustydazzler]

Using it as a screwdriver without going over the torque setting shouldn’t do much harm, but hitting the setting and continuing to tighten, I wouldn’t have thought would do it any good.
I must admit I alway go over terminations again manually with a normal driver at the same time as giving the cable a wriggle near where it terminates doing it that way I sleep better

I do this ALOT and I know it makes using a torque driver a bit pointless but its just the way I'm wired

 

[pc1966]

I do this ALOT and I know it makes using a torque driver a bit pointless but its just the way I'm wired

Why not just go over a 2nd time with the torque driver?

That is what I tend to do as it helps avoid missing a fastener that was just done up lightly when assembling things and also allows for a bit of settlement. I guess it is also partly memory from mechanical devices where you do a set of fasteners up in different torque stages to avoid warping an assembly, etc.

 

[Marvo]

Wheel nuts and electrical terminals are different situations.

The torque value for the wheel nuts is set knowing exactly what is being fitted, what its made of etc etc.

Electrical terminals could have a range of types and sizes of conductor put in them, there may even be multiple conductors in there. I can't see how one universal torque setting can be correct for all sizes and types of conductor.

Here where I am the local regs limit the number of wires in any terminal or termination to two unless it was specifically designed to accept more. Do the UK regs allow multiple wires in a single termination point?

 

[davesparks]

Here where I am the local regs limit the number of wires in any terminal or termination to two unless it was specifically designed to accept more. Do the UK regs allow multiple wires in a single termination point?

Yes they do, there is technically no limit in the regulations. However common sense, good judgement and manufacturers instructions do need to be used.

On a standard ring final circuit in the UK you can expect up to 3 conductors in a terminal, the 2 legs of the ring and a spur.

Then there's split concentric cable where the neutral is made up of a dozen or so seperately insulated conductors which all get put together in the same terminal.

 

[littlespark]

You can bet the powers that be are taking notes…

“Hmmm. Limit each terminal to 3 conductors….?”

“So, new circuit… you can’t use maybe an existing spare mcb?”

“No no… has to be a new type breaker….. with um… new din rail type.. so new circuit means new board!”

Mr Hager: “sounds good to me”

 

[billyblade]

Just thought I'd throw in a few points here. Only skimmed the thread but hopefully, my input might help.

• Every torque screwdriver is sold with a calibration certificate. The standard they are manufactured to states that they should be calibrated every 12 months or 5000 clicks (whichever comes first). The first calibration should be carried out 12 months after first use. For the purposes of the standard, first use is taken as day of purchase so can be carried out 12 months from the date on the purchase invoice rather than the date on the supplied certificate.
• Yes, you should wind torque tools down to the minimum setting when not being used. This releases the tension on the spring and reduces the chances of it drifting out of range.
• A lot of breaker manufacturers are making the holes in their plastic casings too small to get the correct screwdriver down. Installers then resort to using the next size down and this is where breakages can occur., If you don't have a good fit between screwdriver bit/blade and screw recess then all the turning forces are concentrated on one or two surfaces instead of the multiple ones intended. In the case of the +/- blades you can actually get them 90 degrees out if you use one too small and that will almost inevitably cause breakage.
• A lot of breaker manufacturers are using poor quality screws where the fit is not good. This can cause blade breakage/ camming out/ screw damage etc.
• Some of the screws used look like they are intended for a +/- blade/bit but they are actually more suited to PZ or PH. If you have broken +/- blades in the past then try PZ or PH, see if they are a better fit in the screw. They tend to 'enter' the screw recess further than the +/- blades/bits.