Indignation With Taking Liberties

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Larry M
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Re: Should color differentiation matter?
Larry M   11/13/2012 10:03:43 AM
Actually we're all responsive to IR (and presumably UV). The response is just way, way down the curve. The eye (like the ear( is a logarithmic sensor with a range that spans many decades.

In about 1974 I was working in a darkroom testing IR LEDs and phototransistors, using a sniperscope from time to time when I needed to adjust something. After about 3 hours I I realized that I could see the IR emitters without aids. I was able to complete the testing with unassisted vision.

Larry M
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Re: Should color differentiation matter?
Larry M   11/13/2012 10:10:16 AM
Cabe Atwell wrote: "I assume that color blindness is something a field tech or line worker should admit? I will be sure to ask about this issue in the future."

Surprisingly, normal color vision might not even be a requirement for the job. In 1963, as a new high school graduate, I attempted to enlist in the Navy, in a program that included a degree in Nuclear Engineering and service as an officer on a nuclear submarine. At the pre-induction physical my color-blindness was discovered. I was ineligible for the neuclear program and asked the recruiter what other electronics options were available. He responded that the only one was Telephone Installer.

Given that it was common to wire buildings and ships with 25-pair and 50-pair telephone cables, that was surprising to me then, as it still is.

(I turned down the program and went to college instead.)

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I've had a similar experience
scottmorris   11/13/2012 10:40:42 AM
I work at a government R&D laboratory and as such we build numerous prototypes very few of which actually are converted into actual products (we do a lot of speciallty measurement systems).  One prototype that was actually turned into a product had a similar problem when it went to production. 

The instrument is a very large autonomous air sampler first designed and built back in the early 90's.  We built several prototypes and succesfully demonstrated the system.  The government decided they wanted to build several of these instruments to place around the globe.  A defence contractor won the bid to produce said instrument.  We turned over our designs and a prototype to the contractor and were basically held out of any interaction with the contractor.

Once the contractor finished the production prototype we had a look at the system.  It performed as well as our system and they actually fixed some features but as a whole they did not change much wiring or components.  One thing they did do was change all the wiring to white wire. Nearly every wire in the system was white.  One component in particular is a 3U rack mount electronics box. 

This electronics box has 115VAC, various DC power supplies and many signal wires.  There are over one hundred wires in the box and all of it is point to point wiring.  When we designed and built our prototype we used standard colors for all the wires inside this box.  It made troubleshooting, adding and subtracting functions much easier during the prototype stage.  Comparing the contractors version and our version the only difference was that all the wire was white.  All the components were the same and positioned in the same location in the box.

We recently redesigned this box for the contractor.  The main reason for the redesign?  WIRING PROBLEMS!  They said that they subcontract the production of the box.  When they get the box back they always have wiring problems, ALWAYS.  When the system is deployed and put into operation they have additional problems when they troubleshoot and correct problems.


Colorado Native
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Color coded wiring
Colorado Native   11/13/2012 12:06:30 PM
Using the correct color coding is very important, I've worked in TV stations which have hundreds of coax cables running all over the place, all of them one color, generally black.  When one is troublshooting a problem, particularly when you've gone off the air, trying to trace a given cable through this snake pit is very frustrating.  Any type of labeling seems to be the last thing anyone thought of during installation.

On another point, I needed some custom prototype power transformers and ordered them from a recommended source.  The transformers arrived, all were of impecable quality, beautifully finished, except for two things, the color coding of the wires were not standard and there was no documentation.  The primary did turn out to be black wires, the high voltage secondary was blue/grey/yellow, the filament windings, one was red, another green and third was purple/orange.  Not exactly standard coding.  There was no markings to tell which transformer was which except by measuring the voltage outputs.  A high quality product totally messed up by using incorrect color coding and a lack of documentation.  Needless to say, despite the quality, this transformer house is out of business now.  What a shame, a couple of shortcuts by somebody, who knows who, killed the company.

I did send a letter to them asking about the color coding and documentation, I never did receive a reply.

Cabe Atwell
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Re: Color coded wiring
Cabe Atwell   11/13/2012 6:30:22 PM
For the record, the person installing the control panel & wiring was not colorblind. Saying all the wires are grey might have been misleading. As I said, it was just a lazy approach to handling the job at their end.

There are countless laws that regulate color of wiring. Imagine if our homes were wired up with whatever was laying around, or "looked like it would work." I have been in a few homes where the owner took it upon themselves to handle the power distribution. Luckily, they never had an inspection from the city walk through or they most assuredly would have been fined and required to hire an electrician to fix it all. Take the time, do it right is always the lesson.


Dave Palmer
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Re: Color coded wiring
Dave Palmer   11/13/2012 7:12:11 PM
There's no excuse for anyone deviating from a design without proper approval. This is why having a well-functioning process in place for submitting, documenting, and approving or rejecting deviation requests is so important.

That being said, I also don't have a lot of patience with self-righteous engineers who refuse to consider perfectly reasonable deviation requests because "manufacturing should just follow the drawing." These individuals need to get off of their high horse, analyze the consequences of accepting the deviation, and make an engineering decision, rather than a knee-jerk reaction.

Life is rarely neat and orderly; in real-world manufacturing, all kinds of things come up that can't all be predicted, and some of them may require deviating from or changing a design.  A good engineer is able to analyze these things objectively as they arise, and to make sound recommendations.

While the production team in this example was obviously in the wrong and engineering was obviously in the right, the tone of the article seems to suggest that engineering is always right and production is always wrong.  A little more humility may be in order.

One reason why production personnel sometimes make changes without asking engineering is that whenever they approach engineering, they are met with a condescending and dismissive attitude.  So they just stop asking.  This obviously isn't a correct response, but it's an understandable one.

At the end of the day, engineering and manufacturing (and quality, and purchasing, and accounting, and marketing...) all need to work together so that the company can make money and everyone's paychecks will clear.

William K.
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Taking liberties and wire numbers.
William K.   11/13/2012 9:31:46 PM
In my first job that put me in the position of giving instructions to the production technicians, one of my first directives was "If something does not look right to you, please tell me". Not only did that assure that problems were reported as soon as they were realized, it also set the tone for good communications between engineering and production. Some things that looked like errors were just lack of clarity in the drawings, while there were some actual mistakes, although not many. Publicly thanking a tech for finding a problem did a whole lot for moral and greatly improved the cooperation that I got.

There was one interesting case of two detailers who assumed that I had forgotten to put the letter "K" after many of the resistor values in a design sketch that I gave them to detail. Since the first units built from the sketch worked well, more units were built using the finished drawing prior to my being able to check it. The technicians came to me complaining that the design could no longer be made to work at all, and asking what I had changed. It was not until I rescued my sketch that the problem became obvious. The techs got a laugh out of it, and I explained to the detailers in minute detail about not altering my designs. Once again I gave the directive, " if it does not look right, ASK ME". That seems to be the best way to get things right the first time.

Wire colors are an interesting challenge. For most of the auto companies, which were our major customers, there were not very many colors used. Red is for AC, blue is for DC, green is for frame ground, and black is for AC over 120 volts. Wire numbers at both ends of the wire are the way to go. And all terminals to be numbered the same as the wires that terminate in them. Of course the terminals must be in order, which does make tracing much simpler. Even color coded wires must have numbers, since not all cables use the same colors. 

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Re: Taking liberties and wire numbers.
Tom-R   11/14/2012 11:47:32 AM
It's not just wiring that needs proper identification. Piping for water and process materials need the same identification. Imagine our surprise when water began pouring from a newly installed electrical panel. Before the conduit was completed and any wires had been pulled, the plumbers the floor above had mistaken the 1" conduit for a water line they were installing.

As a site engineer I learned to double check all tie-ins, and trace them back to their source. Once when tracing my project's supply lines, I was confused by a nearby fire sprinkler supply line I used as a reference. It was a freshly painted red, but seemed to change position when it ran through a wall. When the maintenance supervisor and I tracked his painter down, we got the answer. Before he started painting in the new room he'd made a point of checking again which pipe was red. He held the brush in that hand, then walked around the wall and began painting the pipe on that side red too... he just forgot he as facing the other direction.

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Two Issues with RVs
wbswenberg   11/14/2012 3:29:40 PM
I have two issues with RVs.  1) using Romex a solid conductor wire in a vibration enviroment. It should be stranded.  I believe it is criminal and hope some day the manufacturers that do this get sued out of business.  The other is the change or lack there of across AC and DC systems.  In AC green and bare are grounds.  Black and colors are hots.  White is neutral.  Except for travelers.  On my camper I put red tape on the + side.  Both terminals are a mixture of black and white wires. 

William K.
User Rank
Re: Two Issues with RVs
William K.   11/15/2012 6:53:59 PM
Absolutely right about the use of solid wire in RV s. I was asked to repair a problem of missing power in an AIRSTREAM trailer, and the very small outlet boxes were wired with solid wire, white and black. The problem was found to be a broken jumper strip on an outlet, making the repair was a real challenge because of the short solid wires. But adding a jumper between the two hot scrfews solved the problem. I am no longer impressed with the quality. Plush does NOT equal quality, nor does having lots of cute features.

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