Electronics > Mechanical & Automation Engineering

copper braid/screen/shield dipped in solder bolted on star earth ground?

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Doctorandus_P:
This wire does not look like it's put in a solder pot.
It looks like that the individual strands are tinned or nickel plated before they are braided together.
It also looks like it is a very low current connection.
I've been looking at that picture a bit, and it does not look like that braid is carrying any current at all. The star point seems to be just for safety GND and EMC grounding.

There is no indication anything in that area is overheated or damaged in any way.
I would say the black PCB's on the left side are far more suspect :)

coppercone2:
it has solder in it, that end piece is totally solid (even on the corners that did not experience pressure), it feels like used solder wick. I would say the problem with that welder is not mine because its an ebay picture of someone elses welder

How do you control the amount of solder that is being chaotically wicked up into the braid?

I just did a test
1) i clearly see a solder boundary
2) in the middle of the braid the metal pick is easily able to get under one of the weaves of wire
3) in the end of the braid where the bolt is, even in the area that was not under bolt pressure, the sharp pick behaves exactly like if was trying to penetrate a solid solder filled area (aka there is no place for the pick to get between the strands)
4) it bends like a solid piece of metal
5) its really obvious that there is a solder boundary

I never saw any standard that gives an acceptable amount of solder in a ground connection.

mag_therm:
I should add to my previous post about historic use of solder dipped braid.
In the USA, for fixed wiring covered by National Electric Code,
soldering is still allowed provided the joint wires are twisted mechanically first.

For some ground conductors (I assume ones that might carry a switchboard full fault currnent,
as protected by the incoming overcurrent protection),
soldering is not permitted. Such conductors would be subject to adiabatic heating during a severe ground fault
The joints are often by listed clamps and approved exothermic welding.

I don't have the NEC code here and my description above is approximate and should be confirmed
by reference to the actual code.
Maybe some on here have the code and can give better info.

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