I have been asked to offer an opinion in a sensitive situation.
A machinist moved his shop across town and required some rewiring (3-phase outlets, conduit, etc.) in order to locate some machines where he wanted them.
He hires a guy who's not a pro (and later discovers is not insured) but has done shop wiring before and had a good attitude and track record. The guy does good work. No complaints about the quality of his work.
Owner throws the switch, all works fine.
The story continues 4 weeks later when the very expensive CNC fries its controller PCB to the tune of $4000.
Turns out the voltage in the shop was upward of 245 and the taps in the CNC's power supply were set for 220.
What is the legal and moral responsibility of each party?
What will not be helpful are replies about the character or intelligence of either of the players or their actions.
The "electrician" is culpable as it was found that the wiring was to blame. That proof alone means that he would be culpable, regardless of his credentials, or lack thereof.
The owner should bear some blame (as in be lenient in court) for trying to economize costs in the wrong area (he should have paid the licensed and insured electrician).
Also knowing how to hook up systems well, and knowing how to do a proper requirements analysis are two different things and define some of the differences between the grunt pulling the wires and the supervisor laying out the plan and making sure that the machines and their power sources are matched. Since a failure mode did occur, it would be improper not to make a negative statement about the character of the installer.
Also, though it was not a lack of intelligence that compelled the owner to choose the riskier path, it does indicate a lack of wisdom, which I am sure has received a boost due to these events already.
Probably a good call, since modern switchers, which the DC supplies for these things usually are, can handle up to about 265 volts. Even a bit more, typically.
Nonsense. The voltage at the panel has nothing to do with the wireman. It's a function of the transformer at the pole. The voltage in my shop, wired with three phase delta, is also upwards of 245 volts.
The only way a wireman could be responsible is if the panel was wired three phase delta, with a high leg, and he had assigned the high leg to one of the
120 volt circuits, yielding 208 or more volts.
The voltage declared indicates that the service is, indeed, delta.
The nominal utility power as supplied is supposed to be 240V. 5 volts over is a touch hot, but not out of the bounds of normal tolerances - turn everything on in the neighborhood some hot August afternoon with the AC units cranked, and tell me what the voltage reads then...
If they were seeing 250V - 255V or more, then I'd call the Utility and get the transformer taps knocked down a notch.
If the power supply on the CNC computer had changeable taps, and the last guy that touched it didn't have any reason to look to see what it was set for, IMHO it's nobody's fault. Especially if the shop they moved from and the one they moved to had the same nominal operating voltage, and they knew it - I'm not going to open 50 machines looking for the unexpected when I'm charging by the hour unless I have a good reason to... Just "Git Er Done" and go home.
If he had a reason to look inside and saw it was on the 220V tap he should have moved it to the 240V - or told the owner - it's good practice to follow but there's no responsibility to look involved.
And I wouldn't expect 255V on the 220V tap to kill it. Now if it was set for 208V input and you fed it off the 'High Leg' from an Open Delta service that's hovering around 280V to ground, THEN I'd expect fireworks. Open Delta High Leg voltages can bounce around and go even higher, then something flashes over...
That would be the /one/ time I'd call it against the Handyman, putting the high leg on the control circuit would be a big goof. You are supposed to put the regular 240V legs on the A and C phases coming in, and the 'High Leg' Orange lead to B phase and NOT the controls.
The average power supply is supposed to feed +5V, +12V & -12V etc. to the computer board, and have Crowbar protection so that's all that gets through. If the supply blows up and lets line voltage through to fry the controller board (even if you put an over-voltage on the input) that's a badly built power supply.
Otherwise, it's entirely possible that it just reached End Of Life and decided to go out in a spectacular manner, and the move had nothing to do with it. The timer that makes things blow up three days out of warranty finally went off.
Unless you want to spend a lot of money on Electronic Forensics to analyze the power supply failure, "The world may never know..."
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PS - Have to trim off alt-r.c.m to make this go, 4 crosspost limit.
** Unlikely it was a SMPS based on the OP's admittedly poor and incomplete info.
Cos SMPS do not have multi-taps for AC input voltage - PLUS if an off-line switcher fails from overvoltage, it just blows the fuse and goes dead.
But losing regulation and over-voltaging the load ( as was alleged by the OP) is another scenario altogether - more often associated with old age or the failure of one of a few critical components in the regulation loop.
Nonsense. If you hire a 'pro' chances are they make even more mistakes. In this case the owner is to blame. He should have hired someone from the company that sells the CNC machines to connect them properly to the mains.
Nonsense? Take your retarded queries elsewhere, crossposting, idiot, troll fucktard.
When a man wires up a machine, it is his responsibility to make sure that the machine he is connecting to power is set up for the voltage he is providing to it.
He is responsible because he did not perform the requirements analysis.
Doesn't matter. The device to be powered must not be wired up with an inappropriate feed, or fail to be set up to take the feed that is provided.
A CNC machine is something different than a light bulb. Few electricians know more than how to connect a light bulb and outlets. Besides, the story doesn't tell whether the machine has a permanent mains connection or is connected by a cord.
BTW, I know of a place where one can get discount bypass operations, endoscopies, and reduced prescription drugs. The guy is a nice guy, and there haven't been any complaints yet. At this location, anyway. And not from any living person.
Perhaps you don't work with many electricians. I work with electricians on a daily basis, and the large majority of them can run the wire to the machine, outlet, light fixture, what ever, but few of them have the ability to make sure it is 100% correct for the equipment powered. I have seen 480 volts wired to 208, and the reverse, single phase wired to 3 phase equipment, wrong rotation, (that had been verified correct by the electrician!), electricians reversing rotation in the equipment so some motors are correct, and some are reversed, you name it! That is where I come in, to double check phasing, verify incoming voltage is correct for the equipment, and to ensure the voltage taps in the equipment is set properly. Unless discussed before hand I would not assume the electrician checked to make sure the equipment was set up for the incoming power. Seems like the owners responsibility to me! Greg
Drier has a temperature limiter, so although the slightly higher voltage results in a slightly quicker "turn on" time for the elements, they still are shut off at the same temperature regardless of incoming voltage.
Which makes ALL of them a mere order taker, point to point wireman.
This was not such an installation. If new runs had to be installed, then the installer, if only a mere electrician, is already in over his head if he doesn't know about the equipment to be fed power to.
A hard wired machine power run, however, should also include insuring that the machine you are hooking up is at least set properly for the voltage you are going to be bringing live on it. As you will have the panel for it open, you should make yourself aware of any voltage taps, so that you don't hook up say a 5% under voltage tap to a 5% or more overvoltage feed.
Any electrician that is a mere, dumb, brain dead wire terminator should be looking toward an industry where his mistakes have less of a catastrophic downside. If you do not take the time to at least examine what you are hooking up, you have no business in the industry.
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