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Perhaps there needs to be several ranges based on cable type , bare , ferruled , bent , multi or single etc
Discuss Torque Talk in the Electrical Forum area at ElectriciansForums.net
Perhaps there needs to be several ranges based on cable type , bare , ferruled , bent , multi or single etc
Spot on.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.
There are plenty of mini-torque wrenches out that that can take screwdriver bits, but fully accept space constraints in some cases.Also to mention some electricians torque screwdrivers only range from 1-3 NM like the Wera , which is a bit naff from a £175 tool when some makes of main switches ask for 3.2-3.4NM
Spot on.
Also wheel nuts are subject to significant forces and vibration making torque settings important. Whereas Domestic Electrical installations are (generally) not subject to these forces & vibrations, and so terminal screws, if nipped up, are highly unlikely to work loose.
hmmm....if temperatures are getting high enough to that then cable is likely undersizedScrew terminals are subject to thermal creep, through which they can become loose, although that's not going to be much of an issue at the time of installation.
hmmm....if temperatures are getting high enough to that then cable is likely undersized
Ferrules on stranded cables will be mandated in regs before long for sure !Happens at moderate temperatures, especially when stranded cables have been tinned with solder. That is why they shouldn't be tinned.
Doesn't necessarily need such high temperatures for it occur.
Ferrules on stranded cables will be mandated in regs before long for sure !
Not exactly, but 526.9.1 says the ends have to be "suitably treated" and ferrules are one way to do that. The other common way is the ultrasonic weld you see on some RCBO neutral tails that are fine-stranded.I think they are mentioned in the regs for fine stranded wires aren't they?
It is more the cycling of hot/cold you get with time-varying loads or, to a lesser degree, just from day/night temperature changes, etc.hmmm....if temperatures are getting high enough to that then cable is likely undersized
Indeed, but who in their right mind gets out the soldering iron station when it takes 2s to put a ferrule on?!Not exactly, but 526.9.1 says the ends have to be "suitably treated" and ferrules are one way to do that. The other common way is the ultrasonic weld you see on some RCBO neutral tails that are fine-stranded.
Also that section (526.9.2/3) say no to tinning conductors for screw terminals, etc.
Soldering is great though if it is actually the means of connection!
You only have to fix one and then take it out again to see where the screw clamped down and all the strands it missed!As above, was quite common and obviously enough for it to be added to the regs as a no-no.
Ferrules are quite a neat way of helping fine stranded wire, and occasionally I have put them on coarse stranded if it is a big screw terminal instead of cage-clamp, etc, as I have seen wires removed and looking worryingly tin and flat as a result.
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.
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