MCB melted

[JohnW2]

Do you boys get your torque screwdriver calibrated regularly? No calibration, no point!

Not in my case, not the least because I virtually never use them. However, as I've said, I do have two, and I do periodically check them against one another. If they every appeared to be appreciably different (which hasn't happened yet), I would (if I were contemplating using them) probably get both calibrated.

Kind Regards, John

 

[EFLImpudence]

It seems that my "manual torque" (as I've used for the past 40+ years) is usually 30% - 50% higher than the 'recommended' torque.

Quite a lot then.

 

[Echo the husky]

I don't often use mine either, the terminals always seem to be alarmingly loose.

I do however use a torque wrench, and trust it, when tightening terminal bolts on large MCCBs, connections in busbar chambers and connections to the soft lead terminals in large lead acid batteries used in central emergency lighting supplies.

 

[333rocky333]

In the real world I reckon few people even own one.
People laughed when I had Modulo screwdrivers, even though most electrical gear use that head type and been around years.

 

[JohnW2]

It seems that my "manual torque" (as I've used for the past 40+ years) is usually 30% - 50% higher than the 'recommended' torque.

Quite a lot then.

Indeed - generally a fair bit closer to 3 Nm than the 1.7 - 2.3 Nm commonly recommended by the manufacturers.

... and that reminds me of my 'suspicions' about how scientifically determined these 'recommended torques' really are. The two most common figures mentioned (1.7 and 2.3 nM) are the metric equivalents of the ('very round') 15 and 20 lbf-in.

Kind Regards, John

 

[JohnW2]

I don't often use mine either, the terminals always seem to be alarmingly loose.

As you will realise, that's identical to my experiences.

The history is that I was given one a few years back, but was so surprised/shocked by how loose it was "telling me" to tighten terminals that I bought another for myself - and was equally surprised/shocked by the second one!

Kind Regards, John

 

[Echo the husky]

That reminds me of a shocking conversation I overheard in the local wholesalers recently, an 'electrician' was returning a load of MCBs with faulty terminals that wouldn't tighten. He was installing the MCBs with an impact driver...

 

[Iggifer]

That reminds me of a shocking conversation I overheard in the local wholesalers recently, an 'electrician' was returning a load of MCBs with faulty terminals that wouldn't tighten. He was installing the MCBs with an impact driver...

What's wrong with 80Nm of force?!

 

[JohnW2]

He was installing the MCBs with an impact driver...

What's wrong with 80Nm of force?!

I think I'd be at least as worried about the effects of the 'impact' as of the excessive torque

Kind Regards, John

 

[Iggifer]

He was installing the MCBs with an impact driver...

What's wrong with 80Nm of force?!

I think I'd be at least as worried about the effects of the 'impact' as of the excessive torque

Kind Regards, John

I saw a guy do it with an impact driver once. The RCBO literally snapped fully down the join in the plastic that runs down the middle of the top. It wasn't even a Proteus device, it was Eaton! He didn't use it after that

 

[Adam_151]

I do however use a torque wrench.... connections in busbar chambers

Nah.. Just hold the rachet handle so that your forearm is in the same orientation as the handle so as to effectively length it. Now tighten it as far as you can go comfortably, its now tight, test by trying a fag paper between lug and busbar.

Hanging off the racket, standing on it, slipping a bar over it or smashing it with a hammer is too tight