Torque screwdrivers

[Jupiter01]

I own a set of straight, pozi and Philips screwdrivers (9 in total). They are the Stanley VDE range and I use them all the time. I occasionally work on Consumer Units and understand that these screws have to be tightened at certain torque levels.

Yes, the obvious answer is that I need to buy a torque screwdriver!

Is there an economical choose given I have the existing set of screw drivers already? Does everyone use a torque screwdriver for the CU?

 

[blup]

Surely it's more important to develop the skill of terminating a wire properly first (I don't doubt you can do that). In my experience as a diyer it is very easy to mis-terminate a wire in, say, a socket particularly when doubling over the copper. The required torque can be met but part of the wire might move during the tightening process or not even be compressed by the end of the screw. A torque screwdriver would not necessarily prevent that, and might give the misleading impression that all is well.

Blup

 

[opps]

I am not an electrician but have lost count of the number of times that supposed electricians have mullered the heads on the screws in CUs. I suspect that it was the result of them using the wrong screw driver profile.

 

[flameport]

Is there an economical choose given I have the existing set of screw drivers already?

A torque screwdriver set doesn't replace other screwdrivers, it's an additional item used for the specific purpose of tightening screws in things like consumer units and anything else where the manufacturer specifies the torque.

Does everyone use a torque screwdriver for the CU?

I use them, and if people are installing consumer units without, then they are not following the manufacturer's instructions.

 

[JohnW2]

Does everyone use a torque screwdriver for the CU?

As you have been told, some will point out that, strictly speaking, you would often not be complying with MIs of devices if you didn't (albeit BS7671 now only requires one to "take account of", not necessarily 'comply with', MIs).

However, maybe it's just me, but, as I have often reported, I have been personally rather 'frightened' when I've used torque screwdrivers for devices within CUs. I have three such tools (two of which were gifts), all of which seem to perform similarly. However, if I use any of the them for the terminal screws of an MCB/RCD/whatever, those screws usually end up far less tight than I would dare to leave them were I tightening them 'manually' - so I don't really know what to say!

I imagine that the experiencesof others must differ from mine!

Kind Regards, John

 

[ericmark]

Before using a torque driver be it on a screw, nut or bolt, the treads must be tested to see they are not binding, and often a lubricant is recomended, the modern method is a combination, torque down first then a extra so many degrees turn.

The problem with the torque driver or wrench, is it removes the feel from your hands, so you can't feel the bolt/nut/screw is binding.

If not tight it heats up, when it heats up it often compresses the bit causing the screw to bind, so it then becomes slack, and the person who tightened it up is blamed for leaving it slack.

The person tightening it up is to blame, but not for leaving slack, but for failing to test threads not binding.

Use of cable ferrells to ensure no stray filaments when using fine stranded wire, or lugs, but this is all experience and skill, not the use of a torque device.

 

[markyd1]

A torque screwdriver set doesn't replace other screwdrivers, it's an additional item used for the specific purpose of tightening screws in things like consumer units and anything else where the manufacturer specifies the torque.


I use them, and if people are installing consumer units without, then they are not following the manufacturer's instructions.

Steady...the Anti manufacturers instructions brigade will be after you

 

[JohnW2]

... the modern method is a combination, torque down first then a extra so many degrees turn.

That's what I do (if I bother with the torque screwdriver at all), since I am too 'nervous' about what the torque screwdriver achieves, but it makes total nonsense of the use of a torque screwdriver. In the sort of context we are talking about, the purpose of a torque screwdriver is not to prevent 'under-tightening', since most people could manually tighten it further, but, rather, to prevent over-tightening.

Kind Regards, John

 

[Keithmac]

How often do you get the screwdrivers calibrated?.

 

[JohnW2]

How often do you get the screwdrivers calibrated?.

I never have - but I have had all three from new, and they have (even when brand new) always all performed very similarly (and still do) - i.e. if I tighten something to a given torque with one of them, I get little, if any, further tightening (to the same torque) by using the other two (and regardless of which I use first).

I therefore conclude that either they are all roughly right (most probably the case), or that all have had very similar errors of calibration to each other, unchanging throughout their lives to date (which seems very unlikely!).

Kind Regards, John

 

[ericmark]

the purpose of a torque screwdriver is not to prevent 'under-tightening', since most people could manually tighten it further, but, rather, to prevent over-tightening.

Yes good point, the idea of the torque screwdriver is so when checking the tightness of terminals during a service you don't to neck off wires by over tightening, the servicing of equipment mounted on a metal structure where vibration could cause terminals to work slack was a regular job until the maintenance free spring loaded terminals started to be used in control panels.

However there is a reference to consumer units, and I have not seen many consumer units serviced as such, they should be checked once of course, after a month or so, as cables heat and cool they can become loose, but not seen it done with any domestic installation, and checking once is unlikely to cause a problem, it is when checked for tightness on a regular basis when the problems start. As with concrete batching plants and the like.

 

[Jupiter01]

Are there any plans and would it be sensible to have maintenance free type connections inside the Consumer Unit?

 

[RandomGrinch]

Are there any plans and would it be sensible to have maintenance free type connections inside the Consumer Unit?

Not quite, but this product seems to be half way there

Wiska 818CUR Consumer Unit Relocation Kit

Wiska 818CUR Consumer Unit Relocation Kit Wiska 818CUR Consumer Unit Relocation Kit is ideal for use when relocating a domestic consumer unit. This consumer unit relocator ensures tidy and secure, maintenance free connections and saves time on installatio

www.electricpoint.com

 

[JohnW2]

Are there any plans and would it be sensible to have maintenance free type connections inside the Consumer Unit?

I'm not aware of it having happened yet, but it would not surprise me if it eventually does. Perhaps virtually 'inevitable' (eventually).

How 'sensible' it would/will be would/will undoubtedly be a subject of 'debate'.

Apart from everything else, one issue would be a practical one. Given that spring-loaded connections are invariably 'one conductor per hole', there would in some cases be a need for at least three 'holes' (i.e. three 'connectors') to replace one terminal ( e.g. both ends of a ring final, plus a spur, originating from an MCB or RCBO).

Kind Regards, John

 

[JohnW2]

However there is a reference to consumer units, and I have not seen many consumer units serviced as such, they should be checked once of course, after a month or so, as cables heat and cool they can become loose, but not seen it done with any domestic installation, and checking once is unlikely to cause a problem, it is when checked for tightness on a regular basis when the problems start. As with concrete batching plants and the like.

Well, again it's not going to be done often (if ever!) in many domestic installations, 'testing' an installation will usually involve disconnection (and subsequent reconnection) of things in a CU - putting one 'back to square one'; (if not worse) in terms of terminal screw tightness.

Kind Regards, John