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Discuss A question about torque screwdrivers in the Electrical Forum area at ElectriciansForums.net

happyhippydad

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I have been umming and arghing about a torque screwdriver for some time but have not yet bought one.

My fears are the following:

1. There are set torque settings that conductors in a consumer unit should adhere to. However, in the neutral bar which are screw terminals I tend to screw a 6mm in tighter than a 1mm (for example), as if you screw in a 1mm too tight it can shear. You can screw in a 6mm pretty much as tight as you can without fear of it going through the copper. I cant see how a torque screwdriver distinguishes between a 1mm and 6mm. Does it? Does it need to?

2. Are torque screwdrivers always accurate? If I use my normal screwdriver I have a 'fairly', if not 'very' precise feel for how tight I have made the connection. This experience will only improve over the years and you will make varying degrees of tightness as required. You lose this with a torque screwdriver and put all your trust in the mechanism.

I wonder if a torque screwdriver may not be a good option for someone who knows how to use a screwdriver properly? However, I am very much open to persuasion hence the post.
 
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Midwest

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I see your point about conductor size, but I don't think it has bearing on it, as you are tightening to a particular torque setting.

Torque screwdriver is as accurate as its last calibration, if you buy a decent one.

I only used mine on a CU installation. I was sometimes surprised at the manufactures torque requirements, which makes you wonder, if we do over tighten sometimes.
 

telectrix

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they are just today's fad. never catch on, same as electric lighting back in the late 19th C, :p :p :p. oops. that one did.
 
I have a Draper torque and rarely ever use it (I trust me own wrist and experience more than I trust a factory made screwdriver)
I keep it just in case I ever get a situation , where a terminal just doesn't feel right...
 

Matthewd29

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I see your point about conductor size, but I don't think it has bearing on it, as you are tightening to a particular torque setting.

Torque screwdriver is as accurate as its last calibration, if you buy a decent one.

I only used mine on a CU installation. I was sometimes surprised at the manufactures torque requirements, which makes you wonder, if we do over tighten sometimes.
I am the same. I had one particular board where it was around d 1.8nm. I certainly would have tightened it more than that had I been using a normal screwdriver. Made me wonder if the slant in MK or MCG boards etc is from me overtightening. Tried another MCG board and they are in fact cheap dirt as even with the torque setting the slant was unbearable.
 
1. Most of the better torque screwdrivers are adjustable for settings, you have to do this manually.

2. NO when mine arrived it was way off, and had to be manipulated to bring it somewhere into specification, it still isn't and I have to adjust down from it's settings to obtain the correct torque, It's an Armeg so not a cheap driver.

Trouble is my elbow is way out of calibration due to Arthritis the pain sets in before I reach any type of torque settings and I tend to relax my arm in response.
 

happyhippydad

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  • Thread Starter Thread Starter
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I see your point about conductor size, but I don't think it has bearing on it, as you are tightening to a particular torque setting.

Torque screwdriver is as accurate as its last calibration, if you buy a decent one.

I only used mine on a CU installation. I was sometimes surprised at the manufactures torque requirements, which makes you wonder, if we do over tighten sometimes.
I see what you mean about 'tightening to a particular torque setting'. I guess they must set the Nm to whatever is safe for the 1mm conductor so it does not cause damage to the copper(yet is tight enough), this same torque setting must be the same for the 6mm which means perhaps we over tighten for the 6mm when using a screwdriver. But can you overtighten a 6mm? If I screw the 6mm in as tight as I possibly can I don't see it getting damaged?
 

telectrix

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if terminating a single 1.0mmin a CU (as is usual with lighting circuits) i always double the end over. this reduces the risk of damaging the conductor. apart fom which. a single 1.0mm conductor in a CU terminal has a chance of not being under the screw, but to one side.
 

Midwest

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I see what you mean about 'tightening to a particular torque setting'. I guess they must set the Nm to whatever is safe for the 1mm conductor so it does not cause damage to the copper(yet is tight enough), this same torque setting must be the same for the 6mm which means perhaps we over tighten for the 6mm when using a screwdriver. But can you overtighten a 6mm? If I screw the 6mm in as tight as I possibly can I don't see it getting damaged?
I remember watching one of those IET panel vids, at an Elex Show, for Amendment 3. The Hager bod, said (IHO), overtightening is just a big problem as undertightening, within the industry.
 

telectrix

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I remember watching one of those IET panel vids, at an Elex Show, for Amendment 3. The Hager bod, said (IHO), overtightening is just a big problem as undertightening, within the industry.
as i came across the other week. meter monkey had sheared the head off one of the terminal screws on the meter Lout. was a right pain getting it out with the juice on.
 

Midwest

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PS; you do have to factor in the cost of re-calibration, which with most makes is gonna be yearly. When I looked at mine, is was a close call between getting it done, and buying a new one.
 
When I checked my new ARMEG I hung a 200gram weight off a 1000mm arm set at 2Nm to check it's calibration, I can do that every year and document it. :innocent:
 

telectrix

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When I checked my new ARMEG I hung a 200gram weight off a 1000mm arm set at 2Nm to check it's calibration, I can do that every year and document it. :innocent:
afaik, the only200gram weight i can think of possessing is myleft testicle. and i ain't about to hang that on any sort of arm
 
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