Workmanship or OCD

[Justloadit]

With tools like these makes screwing fun

[Justloadit]

Are you using it for repairing motor windings?
SPANJAARD LTD, Address: 748-750 Fifth Street, Wynberg, Sandton
Telephone Number:+27 (0)11 386-7100
sell a spray electrical insulatng varnish which can be used on most stators. If you're rewinding from scratch you need something a bit more serious.

We usually use Wilec for most stuff to do with rewinding. They sell a limited selection of insulating resins for trickle and vacuum impregnation of windings.

Nice stuff you pointing too.

No interestingly I am using it to seal case splitting extruded aluminium cases. Cleaning the excess is easier than silicone, and makes the opening of the case easier for repairs, and for resealing.

[ians]

I have a very expensive torque screwdriver( thermal imager) , it scans the connection after a couple days to see if it is getting warm.

There is another way to check your connection and works great for older circuit breakers, check the mV from the top of the breaker to the bottom.

[AndyD]

I have a very expensive torque screwdriver( thermal imager) , it scans the connection after a couple days to see if it is getting warm.

There is another way to check your connection and works great for older circuit breakers, check the mV from the top of the breaker to the bottom.

We also use thermal imaging on our panels but I think the difference is that thermography and even voltdrop only indicate the resistence of the terminations at that moment whereas using the correct tightning torque is insurance that there will be as little degradation of the termination as possible over time.

It's all relative however, if you're using fine stranded wire in compression terminals or if you're fitting your lugs and ferrules by squeezing them with a pair of sidecutters then tightning torques are the least of your worries but as an assembler our crimping tools and other assembly tooling has to be calibrated every year as well.

[ians]

I can understand all that for panel builders working in a cool environment with all his tools laid out on a work bench, but what about the electrician on site, working in hectic conditions under pressure to finish by a deadline, bad lighting with the risk of tools and equipment being stolen who are connecting twin + e, solid strand Or multi strand wires? Something else I have found with lower end circuit breakers, you tighten today, go back a week later and terminals are loose.

[ACEsterhuizen]

Put in a squirt and forget about it.

Electrically Conductive Adhesives been around for some time now.

[Justloadit]

The issue is not whether the screw unloosens by itself, but rather the pressure on the copper wire, along with heating and cooling, cause the copper to deform, and in so doing makes a poor mechanical then off course electrical connection. Locking the screw simply means that the next electrician doing maintenance gets fooled that the connection is tight, where in the meantime the screw is locked, but the copper has deformed and still makes a loose connection.

on home installations, the deformation of the copper may not be a big issue, because the currents involved are small, but in industrial applications where curent can be intheir hundreds, this becomes a major issue.

Another point to consider is the physical deformation of the copper wire may be due to poor manufacturing processes, where the annealing of the wire is not done correctly, which will lead to a softer copper wire, which is subject to easier deformation.

IMHO the torquing of the screws is to also ensure that one does not go past the 'bending moment' of the copper wire in which there is no return to its original state. So over tightening of the screw does not mean a better connection. In fact good practice is to place the copper wire into a ferrule and then compressing the ferrule onto the copper with the terminal. The ferrule ensures a complete compression of the copper evenly into the space allowed.

[ians]

Justloadit, once you get to higher levels of current it becomes a different league, by this I mean lugs, crimpers, nuts and bolts and torque wrenches. Which brings in another pile of issues like indent crimpers, hydraulic crimpers, crimping pressures etc etc etc .

[AndyD]

Many mechanical clamp terminals aren't suitable for use with stranded wire. When you tighten a clamp onto a bunch of wire strands the bunch can flatten or splay causing the terminal to seem loose at a later date. As said by Justloadit above you should ferrule or lug wires at terminations.

I'd never recommend using threadlock or any other setting adhesive agent to secure a termination. You can never accurately re-torque the screw after the application and you'd never be guarranteed a good termination again if it's ever undone and remade during fault finding for example.

I think every electrician, even one who only works on domestic, should own a decent indent crimper. Even a poor termination on a wire carrying a few Amps is enough to cause a house fire that could kill people.

[ians]

Don't get me wrong I agree with the idea of using torque wrenches. We just have to remember we live in Africa and when people can't tell the difference between a PZ and PH chances you aren't gona get a torque wrench to work unless you use the right bit. We have bigger issues to conquer in this industry.