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campdavid
User Rank
Iron
BOTCHED CONSTRUCTION JOB
campdavid   8/22/2012 1:05:50 PM
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THE FIRST THING I SUGGEST IS THAT YOU FIND OUT IF THE CONTRACTOR IA LICENSED AND CERTIFIED TO WORK ON FIRE ALARM/RELEASING PANELS. REQUIRED IN MOST STATES. A RANK BEGINNER SHOULD KNOW THAT ANY INPUT "ABORT" IS LOOKING FOR A CONTACT CLOSURE AND OPERATES IN THE MICRO OR MILIAMP REMGE. BY TIEING IT TO THE NOTIFICATION CIRCUIT YOU ARE DUMPING 1 AMP IN TO THE CIRCUIT. SO FAR AS INDICATED YOU HAVE BEEN LUCKY THAT THE ELECTRONICS HAVE NOT BEEN FRIED. FOR THE SAKE OF YOUR LIABILITY ON THIS PROJECT YOU SHOULD COMPLETELY TEST PANEL WHEN THE PROJECT IS DONE.

rpcy
User Rank
Iron
Re: Experts!
rpcy   8/22/2012 9:49:16 AM
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You're thinking of the Hyatt Regency walkway collapse in Kansas City MO, 1981. The original engineer's design was workable but marginal, calling for two suspended catwalks to be suspended from the same 40-ft threaded rods. When the builder got to that part of the construction, he balked at threading nuts and washers 20 feet onto each rod, so he made what he thought was a reasonable compromise: he'd use two 20 foot rods instead of one 40 foot rod. The top catwalk would hang from the ceiling, and the bottom catwalk would hang from the top catwalk. He ran this proposed change past the inspectors, the chief project engineer, and a few others, and they all approved the change. I use this example sometimes when talking to validation crews, because you don't have to know anything about civil engineering to realize that if the joints where the top catwalk transfers its load to the rod was workable in the original design, you now have two catwalks hanging from that stress point. Nobody seemed to realize this. And even at twice the weight, the joint held when first constructed. It was only when the catwalk was filled with holiday revelers that the joint finally failed, crashing the lower catwalk to the ground, and the upper one pancaking onto it. The contractor's original bonehead error managed to sneak by several other engineers and get approved. It is not clear that the original architect/engineer was ever consulted on this change -- you'd think that if anyone would have picked up on this gaffe, it would have been him/her.

Charles Murray
User Rank
Blogger
Re: Experts!
Charles Murray   8/21/2012 9:39:20 PM
NO RATINGS
Naperlou, I think you hit it on the head here. The installers were procedural people. The other problem is that it sounds like they did a little shortcutting on the procedure.

JimT@Future-Product-Innovations
User Rank
Blogger
Consider it an Investment....
JimT@Future-Product-Innovations   8/21/2012 1:17:21 PM
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Comparatively speaking, I guess its like the Architect overseeing the Construction of a Building ---  you wouldn't be needed for the entire construction  project, but there must be some involvement beyond just handing over a rolled-up set of Blueprints. 

While I don't have experience in Buildings' electrical systems, I do have extensive history in designing electronic products and the associated duties of following the design into the manufacturing stage. 

Manufacturing a product always requires my complete supervision during the initial build and implementation.  Initially, On-Site (factory floor) Instructions;  then supervision; then a little hand-holding; until finally the crew was familiar and comfortable with all the design intents.  Without that necessary involvement (usually lasting anywhere from 1-5 weeks), success would always be jeopardized.  

Think of it as an investment in the processing of your design.  Plus the relationship you build with the people responsible will yield positive results in future design implementations.

naperlou
User Rank
Blogger
Experts!
naperlou   8/21/2012 9:08:43 AM
NO RATINGS
One thing you have to know about installers is that they are procedural people.  Often they don't follow the procedure.  Remember that collapse of a walkway, I think it was in Kansas City, in the 1980s.  It was a celebrated case.  The architects/engineers designed it properly, but the contractors did not follow the drawings. 

I worked at one company where we had complex machines that were installed by field engineers.  To ensure that this was done correctly without having to send out design engineers we started having the field engineers work with the development team during design and development.  This worked really well.  They knew why things were specificed the way they were.  Of course, some of the devices were in places like Hawaii and the northern coast of Germany.  The design engineers were always ready to go there.  Of course, one of the systems I worked on was going to Fort Hood in Texas.  That was always dangled as potential punishment (sort of like being sent to the Eastern Front in WWII Germany).

williamlweaver
User Rank
Platinum
Inventing a Solution...
williamlweaver   8/21/2012 5:55:46 AM
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Thanks for a great (but scary) story, Cabe!  I noticed the Abort terminals are Labeled "+11" and "12 -". Did the contractors mistakenly think that these terminal name assignments were voltages? (+11 - 12 is a spread of 23). Gosh, this sounds like something I would have done. That is why the Engineers were always certain to keep the wires out of the hands of us Scientists. You should have seen them scramble when I approached a drill press...

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