Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.
Among other things, in a different thread, yardiron wrote: How does wiring degrade just sitting?
I don't remember how that conversation ended, but for anybody who thinks that electrical wiring can't deteriorate with age, here's a picture to help change your mind. This cable was installed, indoors, sometime between 1984 and 1990.
Note especially the insulation on the wires where the screwdriver points. These were inside the cable and not subject to any kind of abuse. All I did was remove the outer insulation. For whatever reason, the white and red wires are in pretty decent shape. But as you can see, the insulation is literally crumbling away on the black and green ones. This is one reason we have fuses and circuit breakers and GFCIs and all that good stuff.
Everything degrades with time, including every glue we've ever invented. The only question is how long it might take. Rubber outer coatings and vinyl used as insulation does the same. The material continues to out gas and I suspect a slow chemical reaction continues to take place between the different materials used to produce them, and in the end degrade it. Old houses have a much higher chance of electrical fires for that reason. As Jim mentioned the environment the material is in can make a large difference to prolong or speed up that degradation. So museums spend big bucks on there temperature and humidity control. My best guess is the better wire manufacturer's have discovered additives to help slow the process and the cheap wire doesn't have them. You get what your willing to pay for. There might be something used to color that wire that help speed up the degradation on some but not on other colors.
One has to question how companies can make claims that their products can last 30, 40, 50 years..... when the product has only been out on the market for 3 years. Make you go hmmmmmm....
Part of the extra money for higher quality products does go towards a company's product testing programs Nyle. If the company itself isn't set up to do that in house, there's multiple other outside test facility's that specialize in doing exactly that. From everything I've read and heard about it, they put a product through an accelerated test program with even artificial environments if that's important for product life. Making outlandish claims about product longevity that aren't true would bankrupt a company if they just guessed at it. A start up company who even thinks they might not survive could gamble on pulling a fast one and fold up there tent before anyone starts a warranty claim. A big well known company should be a fairly safe bet they can back up there own claims.
Nothings perfect, so they fail once in awhile and automotive recalls are one example of that. There's also examples of outright lying of course. Volkswagon knowing lying about fuel mileage for there diesel engines would be the best example I know of. There's a massive amount of testing going on for almost anything you can think of. And for the most part the consumers never hear about it at all. Just as one example, I started out as a teenager sampling coal cargo's leaving Vancouver Harbor for Japan. We ran independent moisture, ash content, sulfur, BTU tests, and the shipment was paid for by calculating the exact total price from our tests. That testing cost gets added to the product cost, and whatever the coal was being used for at that time in Japan the end consumer would also be paying for that. Most other bulk cargo's I know of are also sampled and tested. And most large production plants almost always have some kind of in house lab for product quality control.
The Mil spec shipping containers we were required to use by NASA where I worked were purged and pressurized with Nitrogen to maximize the storage life of critical equipment.
Lots of degraded wire in my life...
my dad's house in Mass was pretty old, and In the 80's still had individual crumbling black rubberized fabric wires on ceramic insulators strung through the walls and ceilings, that still powered all the lights and half the outlets.
I looked on google earth and the house still stands. I wonder if those old wires are still energized.
In Amsterdam I had 3-phase connected to a property we bought. 3 thin black wires emerged from the ground and they connected my regulation heavy duty copper cable to them.
Also in Amsterdam, some people had a workshop in an old railway building. again, black mystery wires emerged from the floor.
They weren't paying for the power, so they used more and more, until it fused inside somewhere; the entire underground cable melted and fused together, and 1/3 of Amsterdam central railway station a couple of miles away went dark.
It took them a week to figure out which 100 year old cable was the problem, there were no surviving diagrams and all the "old guys" had passed on.
Bill Shields wrote: Any chance that the specific colored conductors that failed carried more current for a longer time than the others?
Actually, the red and white wires would have been carrying almost all of the current. The black wire was essentially unused, and the green wire really was just a ground connection.
So who knows. As pete suggested, maybe it had something to do with however they colored the wires, or maybe the green and black wires were just feeling neglected.
