Woodworking anyone?

I still probably win on mileage, but cars are way ahead on incomprehensibility.


I base my initial wire order on 2 feet of wire for every square foot of floor.

What happened? They put the drywall up before you finished the last two circuits?

Just out of curiosity, in the small box with all the coax connectors, what's the thing at the top with all the blue wires connected to it?

There is a site on the internet, cable porn, that shows a lot of pics of rather untidy wiring, and then how it should be done.

In a cabinet the size of a large wardrobe, I have installed enough wiring to add another twice its initial weight.
Two days just stripping and terminating the ends with ferrules, and then numbering each wire with clip on numbers, another three to chase each control wire into place and prove its in the right place.
Then another three days as quality control double check everything "just in case", and then fire it up connected to dummy loads to prove its working, then a day and a half swapping out the expected failed relays etc, and then another week or so polishing up the computer code to go inside as well.
It was a complicated control cabinet for an industrial size type HVAC unit....
The cabinet was man-handled into place by hand before we started, it needed a heavy forklift to move it, because we built it on a reinforced pallet, but the bits of electronics inside, took it over the loading limit of a 7.5 tonner by the time we finished...
It did have a transformer or two in the base, oh, and a battery backup in case of power-cut to shut down everything in a controlled manner, whilst firing up a small generator also on site that would work with the heating boilers to ensure a cooldown that didnt break the boilers, several control boxes full of small computers, and a LOT of relays that went from .05volt to 480 volt and all points inbetween as the control schematics got "Complicated".....

I believe its still working today, but has been refurbished at least twice?..

Mores Law states that its probably all being done on a small laptop by now, and all the actuators are being controlled remotely.
Like Wireless remote, not just the next room and a long cable....

The ones I were looking at were a form of single wire control system that uses basically the same technology as networked computers in that all control modules have their own mac address and are all linked on one HUGE single wire network.
They draw their own power locally, but are switched on and off remotely... some can be done wireless, but mostly the single wire control, acting like a very long "areal", broadcasting all signals down that wire but addressing them individually.
But the individual control all other control panel now doesnt have to have 480volt buzz-bars in it, [thats a busbar that hums slightly?... ] but can operate on 240volt supply and just the one transformer, because apart from the single small Micro computer running the code, there isnt much else in them these days.
It has to be the same cabinet, because we concreted the screws into the floor, and that aint coming out easily, its NOT a wireless computer, it has to be accessed manually, thus completely hack proof unless you have at least a dozen keys to get through all the doors, and all the local control, such as say individual heat settings for the Gym on the 111th floor, are sent down the buildings own separate internal LAN cabling for the HVAC alone.

The control panels for the boiler wont change at all unless they replace or refurbish that boiler package.

Reason they keep the cabinets that big anyway, firstly, its what people expect, and secondly, why replace, because that room was built for that cabinet, there isnt much else need for that room.

We had that problem in the older ones, that it could have a delay in response, and had to drop all the way through the loop before it could go around again.
So we had to design the command to work in that way.
Yeah a whole second.... thats an awful long time isnt it?.
In the cases where that wasnt a sarcastic response, such as overheat protection on the back-end of the boiler, flue dilation fan temps, etc, we quickly realised that a small secondary control micro [for instance what we would now think of as a Raspberry PI] controlling the pieces that needed a fast response and feeding back an error code if there was need for it.
I suppose its like having a Multi-core computer where all the cores are in different parts of the boilerhouse.
On a case of heat needed, the main control sends a "heat on" signal, and the smaller micro did all the local control of the boiler called.

In systems where a failure could cause serious trouble, the primary safety limit monitoring devices are always wired to operate autonomously of the control system. For example, an over pressure limit on a boiler will be wired directly to the fuel shut-down circuit. If the limit trips, the boiler is going to be shut down from outside the control system loop. The limit device contacts will be monitored so the control system will know what happened, but will not be able to override the limit device unless the system is specifically designed to do so. In a properly designed system, the control system should have detected the over pressure condition and took action before the primary safety device tripped but just in case it doesn't, the safety device has priority.

In the A/C control system I design for use in ambulances, there is a high pressure limit switch that is wired directly in series with the compressor run relay. If that limit opens, the compressor is going to be shut down by a hard wired connection. The control system monitors the voltage across the high pressure switch contacts. If voltage is detected, the control system also shuts down compressor operation and sets an error code so the technician troubleshooting the system knows why the compressor shut down. In the event that something happens, such as welded relay contacts, where the safety limit switch still can't shut down the compressor, there is a high pressure relieve valve that opens and blows the refrigeration charge out. While keeping something from exploding, that tends to upset the environmentalists. On the electric heat side, there are two over-temperature limits. The first one, set at a lower temperature, will reset itself if the temperature returns to a safe value. The second, higher temperature one, is a one-shot thermal fuse that if tripped, must be replaced.

That's why in operating rooms and intensive care units they often have isolated power systems with no GFIC protection. If you do get a ground fault, it doesn't matter because all the "hot" power leads are still isolated from ground. Also, most equipment considered life support, where if the equipment fails the patient dies, has redundant back-up systems built-in. I use to service a unit that was an external artificial heart. It had two back-up system built into it. If the main system failed, it would sound an alarm and automatically switch to a completely independent battery back-up system. The battery system was rated for an hour but would actually run for closer to two. If the battery back-up failed or the batteries ran down, you could open a door on the back of the unit and pull out two foot pedals. You could then have someone sit there and pump the pedals, sort of like an old pump organ, and keep blood flowing. You could keep the patient alive as long as you could find someone able and willing keep pedaling. In my service area, I only know of two instances where the pedals were used. One was in an ambulance that got into a wreck while transporting a patient from a remote hospital to a heart center hospital. The wreck knocked out the inverter in the ambulance and the unit automatically switched to battery. It took a long time to get another ambulance on site and the batteries ran down. They then switched to the pedals. Once the replacement ambulance got on site, they were able to again power the equipment from the new ambulances inverter.

The second case of having to use the pedals was pure stupidity. A nurse unplugged the pump while working on the patient. It automatically switched to battery and sounded the alarm. She silenced the alarm but never plugged the unit back in. After the unit again sounded the low battery alarm, everyone panicked and started using the foot pedals. All they really had to do was plug the machine back in, but they didn't realize it until someone got there from biomedical engineering and plugged it back in for them. They still insisted that the machine be serviced and that somehow it was the manufactures fault that they sat there for two hours using the foot pedals.

...There is now.
"Back in the day", we had mechanical over-pressure devices, mechanical thermostats on back end over heat, and flue dilation fans that only had two settings, on or off, and there wasnt any "clever" electronics doing overwatch for any sub system, just the one I had, it was the first micro controller used in these situations...
Bear in mind, before me, the caretaker of the building had to come in and fire up the boilers at "00:My God Its Early" to provide heat and hot water for the cleaners etc?.

In all of the mechanical devices, we never remove them, they are always replaced, serviced, and reinstalled, they are important.
But now they have micro controllers that should shut down the call before it gets to the mechanical device being needed.
Before that, it was the system that I was programming that did all that work...
And thus because of my programming, we realised that a second is a long time, and sub-controllers were needed.
Sub controllers that deal in "thousandth of a second" decisions...

And I monitored the alarm calls, and being able to phone London from my desk in Trafford Park and tell them "Your heating system has a problem and has tripped the Gas Valve", because their boiler had overheated, requiring a hard reset, caught many by surprise, because in many cases, they didnt realise that yet...
And yes there was further investment in that plant in that if I can "see" there is a problem, and "see" that there is no reason, other then just a very twitchy overheat protect, then their aged boiler may need a better control system, regardless of what the original brief was, and yes we can supply more equipment from our own firm to do that, no you dont need a new boiler, just a "shunt" system that when there is an overheat, the system goes to heating the calorifiers [DHW Domestic Hot Water} immediately whilst they boiler shuts down, and we can now start building a prediction system in, and why we are now going to suggest you look at a VT Variable Temp rather than constant temp heating control, in that, we start backing off the temp of the heating system runs at the closer the building gets to occupied ideal temp....
They had a six package boiler system that had previously been run on a constant temp circuit, only backing off one or two boilers when it started getting warm, but still trying to shunt overly hot heating water to all radiators.
Problem is, when it finally gets hot, all that hot water now starts completing the whole system, and their aged boiler package "Panicked".

Also, we invited them to look at a new relay...
Being they had to find the caretaker to do a manual reset, why not let an engineer in Manchester do that for them?.
Yes, we CAN do that, we can phone up the system and trigger a switch that will reset the gas valve for you.
Thus the building wont go cold whilst your finding the caretaker.

Bear in mind, these were days before internet, this was a "Dark art" to many, that computers could talk to each other over a phone line.

Not only was I born before the internet, it was people like me, doing what I did, and possibly with input from ourselves, that invented the internet in the first place...?.. we all knew that a better system was needed, and local networks were going to get a hell of a lot bigger.
TimBL, (Sir) Timothy Berners-Lee, did all that in 89, I was working in communications between 82 to 92, and the Internet was a step up from a network of local and in my case not so local network by computers, what he did was take all the good ideas and go one stage better, and for that Sir, we salute you.

Its easy to look back and say "well of course that was what was needed", but back then, no one had ever thought of a world wide web, and even less of one that would be "Always on" either.
Most of my comms work was setting up a series of computer controlled phone calls in series between 11pm and 4am to interrogate all the systems we had in operation and get the last 24hrs run data.
In 1985, my computer alone, ran up a phone bill of £4,000, a quarter... thats £16,000 a year.
That was more than I was getting paid?.

And 9k2 baud was a good speed back then for a modem. 9,200 bits per second.
My current computer loads than in so much less than a second it can stop and have lunch in the time left?.