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.

Thanks.
--
John English

On Sat, 4 Jul 2009 23:40:18 -0700, the renowned John E.
wrote:

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.

Thanks.

IMO, 11% high voltage over nominal should not "fry" the controller
board in the first place.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

"John E."

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 a STUPID troll !!!

The PSU in the CNC blew cos it was a pile of **** PLUS the design was 100%
incompetant cos it gave no protection to the delicate and expensive load.

Bet it was old and way past use by date too.

**** off TROLL !!


..... Phil

On Sun, 5 Jul 2009 17:13:32 +1000, "Phil Allison"
wrote:


"John E."

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 a STUPID troll !!!

The PSU in the CNC blew cos it was a pile of **** PLUS the design was 100%
incompetant cos it gave no protection to the delicate and expensive load.

Bet it was old and way past use by date too.

**** off TROLL !!


.... Phil


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.

On Sat, 4 Jul 2009 23:40:18 -0700, John E.
wrote:

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 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..."

-- Bruce --

PS - Have to trim off alt-r.c.m to make this go, 4 crosspost limit.

"Archimedes' Lever"
"Phil Allison"

"John E."

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 a STUPID troll !!!

The PSU in the CNC blew cos it was a pile of **** PLUS the design was
100%
incompetant cos it gave no protection to the delicate and expensive load.

Bet it was old and way past use by date too.

**** off TROLL !!


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.


** 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.



...... Phil

On Jul 5, 2:40 am, John E. wrote:
Turns out the voltage in the shop was upward of 245 and the taps in the CNC's
power supply were set for 220.

As others have said, there's not much the wiring guy could have done
wrong to get 245 volts rather than 220. He hooked up what was there
and couldn't be expected to have detailed knowledge of what the owner
was going to run, what setting he had it on or how sensitive it was.

Does the owner have some reason to believe that this was not the
voltage in the new shop before the additions?

John E. writes:

What is the legal and moral responsibility of each party?

None. It is George Bush's fault.

John E wrote:

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.

It is the owner of the shop to make sure the electrician he hired was licensed
and if needed insured. Since you did not say where this happened, I can only
make a blanket statement.

If the "guy" represneted himself as a licensed electrictian, then there may
be some criminal liability here for fraud. If he did not claim to be licensed,
or the owner of the business knew that he was not licensed, he is free and
clear.

If the owner hired him knowing he was not licensed, then it was his
responsability to hire a licensed electrician to inspect the work before
he "threw the switch". If he did not, he may be subject to criminal and
civil penalties, have his electricity turned off, etc.


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.


And how do you know that? What device did you use to measure the voltage.
Assuming the voltmeter was accurate to 2% and rounded up, 240 volts would read
245. The difference is negligable anyway.

As for the voltage setting on the device, it's not the "wiring guy's" job.

Would you want some random "handyman" poking around inside of an expensive
CNC machine?

What is the legal and moral responsibility of each party?

I am not a lawyer, but from my (mis)understanding, as long as the "guy" did
not represent himself as an expert on the machine in question, or as a licensed
electrician, ALL of the responsability falls on the owner of the business and
none on the "guy" or anyone's insurance company.


What will not be helpful are replies about the character or intelligence of
either of the players or their actions.

Well, I'm going to make one. If the "guy" was up front about his not being
licensed, nor trained on the insides of the CNC machine, he is of good
character and reasonable intelligence.

Let's just say that the person who hired him was also of good character and
intelligence, but ignorant of the law and the requirments of equipment.

He's lucky that all he suffered was one $4000 board failing, not his
entire factory burning down around him with no insurance.

If in the future, he does not hire a licensed electrician to perform the
necessary inspections, etc, nor a properly trained technician to inspect
the equipment, you can say something very different.

I also think it is fair to assume that he has by now had a licensed electrician
in to inspect the work, and a trained technicain in to check all of his
equipment. If he has not done both.........


BTW, if both locations are connected to the same "power grid", it is
unlikely that the line voltage was 220 volts in the old location and 240
in the new one.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

On Jul 5, 4:40*pm, John E. wrote:
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.

Thanks.
--
John English

Tempting as it is to blame your Mr Bush for all the eveils of the
world, including my hens not laying, I would propose the following:
1.As noted, the main supply voltage is nominal, variations are normal
and to be expected.
2.Possibly, if the machine was let stand for a while in the unpowered
position, and it was an old controller (and with a linear power
supply, it probably was,) then the electrolytics in the power supply
could have failed due high ESR, and then it lost regulation and fried
the board.
3.My humble opinion is to just mark write it off to bad luck.
Otherwise, get the lawyers involved for years and huge amounts of
money......

Andrew VK3BFA

On Jul 5, 4:40*pm, John E. wrote:
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.

Thanks.
--
John English

Tempting as it is to blame your Mr Bush for all the eveils of the
world, including my hens not laying, I would propose the following:
1.As noted, the main supply voltage is nominal, variations are normal
and to be expected.
2.Possibly, if the machine was let stand for a while in the unpowered
position, and it was an old controller (and with a linear power
supply, it probably was,) then the electrolytics in the power supply
could have failed due high ESR, and then it lost regulation and fried
the board.
3.My humble opinion is to just mark write it off to bad luck.
Otherwise, get the lawyers involved for years and huge amounts of
money......

Andrew VK3BFA

On Sun, 5 Jul 2009 02:04:47 -0700 (PDT), Larry The Snake Guy
wrote:

He hooked up what was there
and couldn't be expected to have detailed knowledge of what the owner
was going to run,

You're an idiot. If you are wiring POWER runs, you had better know
what your loads are, and how they get connected.

In article , wrote:

BTW, if both locations are connected to the same "power grid", it is
unlikely that the line voltage was 220 volts in the old location and 240
in the new one.

Incorrect. Distribution voltages are on the order of a few thousand volts,
stepped down by transformers at the point of service to a few hundred. New
location = different transformer = possibly different service voltage even if
the distribution voltages are exactly the same.

That said, though.... any device designed for 220V should be able to handle
245V.

In article .net, wrote:
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.

Hard to make the case after 4 weeks that _anything_ the electrician did had
anything to do with this. At four seconds, or even four minutes, I'd consider
it obvious. But four weeks went by, and the owner thinks the electrician
caused this? No way.

Turns out the voltage in the shop was upward of 245 and the taps in the CNC's
power supply were set for 220.

So what? Equipment designed for 220V should be able to handle 245V. It's not
the electrician's responsibility to open the CNC machine to see what it's set
for.

I would have two simple questions...

1. Did the electrician have any control over the voltage when the system was
rewired?

2. Is it normal for electricians to measure the voltage, and "do something"
about it if it's not correct (if only reporting the problem to the
businessman)?

Doug Miller wrote:

Incorrect. Distribution voltages are on the order of a few thousand volts,
stepped down by transformers at the point of service to a few hundred. New
location = different transformer = possibly different service voltage even if
the distribution voltages are exactly the same.

Yes, BUT, a power company attempts to keep a constant voltage throught their
service area. While the voltage fluctates due to equipment, load, etc, I don't
think you can honestly say that if it is 220 volts on one side of town, the
same "grid" produces 240 on the other side of town. It might be 242 in one
place and 239 in another, but even that's a big difference unless there is
a heavy load in one location and not another.

The EU spec allowing household line voltage to be 240 volts while claiming 230
was to allow the UK to keep their current system while being "in spec" but I
doubt it was intended to allow variations from as much as 220 in one place
and 240 in another within the same country.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

William Sommerwerck wrote:

1. Did the electrician have any control over the voltage when the system was
rewired?

2. Is it normal for electricians to measure the voltage, and "do something"
about it if it's not correct (if only reporting the problem to the
businessman)?

You missed the point of the original post. The person who did the work was
NOT an electrician, they were a "handyman" hired to do the work.

Since the person never said where they were, it's hard to guess what the
rules are but in (almost?) every jurisdiction that licenses
electricians, a license is needed to do electrical work.

If an unlicensed person does electrical work, the work has to be inspected
by a licensed electrician before the power is turned on. If that was not the
case, there would be no point in licensing electricians, would there?

Geoff.
--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

I work on lasers that use a buck/boost with 16 tap possibilities on 3
phase all the time, and I used to use the same units in theatrical
touring service until more modern solid state lasers dominated the
laser show industry. . From that perspective, I'm amazed at the
replies here that have failed to ask two simple questions. I will
state that I never met a house electrician who ever looked at the
rating plate on the gear, although I did have a few that asked about
phase sequences.

Two, I never met a house electrician who ever checked anything
hooked to the pigtail I gave him to connect, including "professional"
rental generator technicians (actually they were the worst) In the
theatrical business, it is up to the touring operator to check the
local guys work, and in most cases, we preferred they stand in a
corner and watch us, after your first blown passbank with 3 or 4 out
of 22 power transistors blown in the laser, you get the idea to check
the taps both preshow and under load condition. In one case I asked
for 220/3, went to lunch, and came out to find 380V European power
from the generator in my distro box, which is why the box had its
own"tagged out" disconnect switch. Its a rotary switch in big modern
generators, easy to mess up.

Questions:

One, Did the "electrician" hook straight to the machine's tappable
control transformers, or did he meet a simple junction box on the
side of the machine. If it were the later, I'd say he's off the
hook. On the other hand if he was staring at a tap strip , he should
have asked. There is also the possibility of a "cascade" of
transformers in some machines, ie little CTs all over the place in the
machine, that need tapped. ??????

Two, Did anybody bother to read the manual chapter on setup? Machine
shop gear needs leveled and "trammed" when moved, its not a simple
matter of tossing a CNC off the truck onto any old pad of concrete and
expecting good parts to tolerances, and the first paragraph usually
reads, something like "check settings" and have appropriate safety
gear. ??????

The fault occurred months down the road, a instant "oof and shower
of sparks:" would point to the electrician, but months down the road
is lack of due diligence on the part of the owner.

I would have two simple questions...

1. Did the electrician have any control over the voltage when the system was
rewired?

No.

2. Is it normal for electricians to measure the voltage, and "do something"
about it if it's not correct (if only reporting the problem to the
businessman)?

This is the basic question I'm asking. Is it common and regular practice to
inform the owner of a voltage as high as 245? And to suggest that he have
factory personnel come and look at each machine and examine PS taps and such?
And if he had hired a licensed electrician would the electrician likely had
informed the owner of the voltage difference?
--
John English

"John E." wrote in message
obal.net...
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.

Thanks.
--
John English

Well, that eliminates anything that I would have to add to the conversation.

Steve

1. Did the electrician have any control over the voltage when the system
was rewired?

2. Is it normal for electricians to measure the voltage, and "do
something"
about it if it's not correct (if only reporting the problem to the
businessman)?

You missed the point of the original post. The person who did the work was
NOT an electrician, they were a "handyman" hired to do the work.

I didn't miss the point (I think). He was doing the work of an electrician.
And whether or not he was a licensed electrician, he is still morally
responsible for the quality of his work. (Think Hamurabi.)


Since the person never said where they were, it's hard to guess what the
rules are but in (almost?) every jurisdiction that licenses
electricians, a license is needed to do electrical work.

If an unlicensed person does electrical work, the work has to be inspected
by a licensed electrician before the power is turned on. If that was not
the
case, there would be no point in licensing electricians, would there?

No, there wouldn't be. But if he botched the job, he has to be held
responsible. Doesn't he?

Of course, one might argue that if the person who hired him /knew/ he wasn't
an electrician, and didn't have the work inspected, then he (the hirer) is
responsible for whatever went wrong.

In my opinion, No and no to both your questions below. The result would
likely have been the same.

Bob

"John E." wrote in message
obal.net...
This is the basic question I'm asking. Is it common and regular practice
to
inform the owner of a voltage as high as 245? And to suggest that he have
factory personnel come and look at each machine and examine PS taps and
such?
And if he had hired a licensed electrician would the electrician likely
had
informed the owner of the voltage difference?
--
John English

245 volts is only mildly on the high side and should not cause the
symptom described.

i

On 2009-07-05, John E wrote:
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.

Thanks.

"Ignoramus20157" wrote in message
...
245 volts is only mildly on the high side and should not cause the
symptom described.

i

But iggy, we have to BLAME someone! The guy hires some unqualified person
to hook up used questionable machinery. The blame has to go somewhere. I
know where I'd direct it.

Steve

John E wrote:

This is the basic question I'm asking. Is it common and regular practice to
inform the owner of a voltage as high as 245? And to suggest that he have
factory personnel come and look at each machine and examine PS taps and such?
And if he had hired a licensed electrician would the electrician likely had
informed the owner of the voltage difference?

What you have not said is what was the voltage supposed to be?

Where? Common and regular practice as you call it varies from country to
country.

Also what was the actual voltage at the old location. If it was supposed to
be 240 volts then 245 is well within actual variations, or the calibration
of a meter.

If it was supposed to be 208 or 220 or 308, etc then it is too high.

This to me is starting to get tedious. A simple question of "who was at fault"
has become a "****ing contest" over who can make the most outrageous guess
as to why their champion is guilt free.

IMHO it really boils down to exactly what the owner of the business expected
when he hired "the guy". If he hired someone he knew was unlicensed, he
should have had the work inspected or hired a licensed electrician. Otherwise
he was taking a chance that he would never get caught cheating, and he lost.

As for the CNC device failing, his expectation of "the guy" to open it up
and adjust the voltage tapes is unreasonable. Again he took a chance that
he could move the device without hiring the proper technician to pack it up,
unpack it after arival and set it up. And again, he lost.

Considering the worst outcome of it would have been a fire destroying the
building, everything in it and killing all the people involved, a $4000
controller failure, which was probably not caused by the voltage problem
anyway, is a small price to pay for loosing.

As for insurance, no property insurance will cover damage due to illegal
repairs, etc, which includes uninspected work done by unlicensed electricians,
and no manufacturer will cover damage due to untrained technicians modifying
the equipment (even to move the voltage taps), or damage caused by over
voltage due to an unlicensed electrician wiring the equipment.

There may also be civil and criminal liability here, the best thing to do
IMHO is to have the company and "the guy" come to an agreement where they
will leave him alone, and eat the loss. They will then pay for any repairs
to the equipment and "the work" as legally mandated.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

Nominal 3 phase voltage is 240v, nothing wrong there.

Sounds like the CNC tap was incorrectly selected. What were the other
options?

I know of ground problems with CNC's and Com cards that can cause the
same problem.

I believe it is something else, 245 is only 11% high, not a really big
issue.

Cheers

"Ignoramus20157" wrote in message
...
245 volts is only mildly on the high side and should not cause the
symptom described.

i

On 2009-07-05, John E wrote:
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.

Thanks.

John E. wrote:
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.

Thanks.

4 weeks is a long time. Especially on a used piece of equipment that
has been subjected to the strains and jostling of a cross town move.

Can you prove that the incoming voltage was 245 when the "electrician"
was on site?

Were the field connections made by the "electrician" made to a terminal
strip or to the original tails? IOW, Did he see/know that there were
tap options?

If it took 4 weeks to fail in the new shop, do you know that the old
shop didn't also have an overvoltage situation? Maybe the failure was
75% along before the move.

One of the side effects of the slowdown in manufacturing demand is that
there does appear to be an upward creep of utility supplies, in our
shop, this spring our water pressure began to creep upward to the point
where the TP valves on both water heaters began to dribble. Our supply
voltage is a few volts higher too.

If the "electrician" feels like he did miss something, he probably owes
the owner a pro-rated share of the cost, but if he feels he did the job
within the scope of the work he was hired to do, the owner ought to foot
the bill. Whether the 'electrician' gets future work or references
might factor into this....

Equipment is designed to operate +/- 10% of the nameplate rating. In the
case of taps like what happened here, the taps are supposed to be set by the
electrician to fall within the 10% range. With the taps set at 220v the CNC
machine was good to operate from 218v to 242v. As the power installer, it
was the electrician's responsibility to verify the voltage coming into the
building and adjust the taps on the machine accordingly. He was paid to
correctly hook up power to the machine and failed to do so.


"John E." wrote in message
obal.net...
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.

Bruce L. Bergman wrote:

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.

My drier sees 250VAC. Low voltage stuff in this house gets 125VAC.

Everything is working just fine.

Jon

John E. wrote:


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.


I'm going to translate this. Hires a guy that isn't a licensed electrician but does do
the job for less than the licensed guys with liability insurance.

Now your friend that was shopping for a free lunch now wants his evening meal paid for.

We don't know the voltage it was running at prior to the move, we don't know the
variability of the supply voltage where it is now.

The handyman wired it to the disconnect. Made sure there was power to that point.

Somewhere after that the machine was powered up. I'm going to assume for the sake of
argument that the handyman got the shop owner or the owners designee to do it. I don't
know any compenent electricans or for that matter decent handymen that will turn on a
complex piece of equipment on their own.

So the owner or designee that has the manuals and such for the machine and should be the
most knowledgeable person in the room is the one that is at fault.

Wes

Rich. wrote:


He was paid to
correctly hook up power to the machine and failed to do so.


That was NOT what was stated. From the original post:

"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."

If the person was hired to run the wiring, as described above, he had nothing
to do with what was plugged into the outlets and did what he was asked. You
ASSUMED he opened the machine up and connected the wires, something which
was not said.

Since we have no idea of what really was specified, all we can do is speculate.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

"John E." wrote in message
obal.net...

2. Is it normal for electricians to measure the voltage, and "do
something"
about it if it's not correct (if only reporting the problem to the
businessman)?

This is the basic question I'm asking. Is it common and regular practice
to
inform the owner of a voltage as high as 245? And to suggest that he have
factory personnel come and look at each machine and examine PS taps and
such?
And if he had hired a licensed electrician would the electrician likely
had
informed the owner of the voltage difference?
--
John English


It is not regular practice to inform the owner, unless something is found to
be wrong. Having 245v in the building is not normal, and there is a lot of
equipment out there that does not have taps. Equipment without taps could be
damaged by this higher than usual voltage.

It is the responsibility of the electrician to make sure the equipment he is
wiring can correctly run on the power being supplied. IMO the electrician
did not do his job correctly.

My drier sees 250VAC. Low voltage stuff in this house gets 125VAC.
Everything is working just fine.

sniff sniff Is that burning cotton I smell?

William Sommerwerck wrote:
My drier sees 250VAC. Low voltage stuff in this house gets 125VAC.
Everything is working just fine.

sniff sniff Is that burning cotton I smell?

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.

Jon

Rich. wrote:


It is not regular practice to inform the owner, unless something is found to
be wrong. Having 245v in the building is not normal, and there is a lot of
equipment out there that does not have taps. Equipment without taps could be
damaged by this higher than usual voltage.


Where, no one will say where this is. As for the voltage, here in Israel
230 volts is normal, 245 is not. In the UK, 240 is the "nominal voltage",
245 is less than 3% high and well with the accuracy of a random voltmeter.

In the US, the nominal line voltage is around 127 volts, specified to be
120, BUT the system almost everywhere is a 240 volt 2 phase system, with
one phase to ground being "120" volts and the voltage between them being
"240" volts.


It is the responsibility of the electrician to make sure the equipment he is
wiring can correctly run on the power being supplied. IMO the electrician
did not do his job correctly.


Only if the electrician is hired to hook up the equipment to the power line
and adjust the equipment as needed. If an electrician is hired to run some
conduit with a connection to a panel at one end and an outlet at the other
than there is no responsability for the equipment that may be plugged into
it, or the actual voltage.

Since there was no electrician here, just an unlicensed "handyman", there is
even less liability.

The original poster asked what was reasonable and customary. The answer to that
is:

1. Hire a licensed electrician to run the wire and make sure the outlets are
up to spec according to the applicable law.

2. Hire a technican authorized by the manufacturer of the equipment to
properly pack it up, unpack it after moving and hook it up, making any
adjustments as needed.

For the first, nothing else is legal, and therefore anything else (except
inspection by a licensed electrician) is reasonable.

The second is a little more fluid, but the manufacturer would argue that
using someone who is not authorized to make connections, modify the equipment,
etc voids their warranty, so one can argue that is the customary practice.

I guess you can argue that it is customary to cheat on the license for small
electrical jobs, and the certification of technicians for repairs, etc, but
that custom also carries the burden of accepting responsability for any
damaged caused by the people who do the work.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

"Doug Miller" wrote: (clip) That said, though.... any device designed for
220V should be able to handle
245V.
^^^^^^^^^^^^^^^^^
Years ago when household appliances ran on 110 volts, we had 220. Since
then, voltage from neutral to either side rose to about 120, and voltage
across both side rose to 240. For some reason we still talk about 220 as
though it were double 120. What I'm getting at is that systems are no
longer designed for 220--it's 240, so the discrepancy is only 5 volts, and
that's trivial.

I'm guessing that the failure was due to some totally different cause, not
an error in line voltage.

In article , wrote:
Doug Miller wrote:

Incorrect. Distribution voltages are on the order of a few thousand volts,
stepped down by transformers at the point of service to a few hundred. New
location = different transformer = possibly different service voltage even if
the distribution voltages are exactly the same.

Yes, BUT, a power company attempts to keep a constant voltage throught their
service area. While the voltage fluctates due to equipment, load, etc, I don't
think you can honestly say that if it is 220 volts on one side of town, the
same "grid" produces 240 on the other side of town. It might be 242 in one
place and 239 in another, but even that's a big difference unless there is
a heavy load in one location and not another.

You're missing the point. This has nothing to do with the voltage supplied
by the utility. The utility doesn't supply 220V or 240V or whatever. They
supply (for example) 4KV. A transformer at the point of service reduces that
to 220V, or 240V, or whatever. Different transformers connected to the *same*
4KV primary voltage could easily produce different secondary voltages.

In article , "William Sommerwerck" wrote:
I would have two simple questions...

1. Did the electrician have any control over the voltage when the system was
rewired?

2. Is it normal for electricians to measure the voltage, and "do something"
about it if it's not correct (if only reporting the problem to the
businessman)?

Assuming a nominal 240VAC supply, 245V is in no way "not correct" -- it's only
about a 2% overvoltage.

In article , "William Sommerwerck" wrote:
1. Did the electrician have any control over the voltage when the system
was rewired?

2. Is it normal for electricians to measure the voltage, and "do
something"
about it if it's not correct (if only reporting the problem to the
businessman)?

You missed the point of the original post. The person who did the work was
NOT an electrician, they were a "handyman" hired to do the work.

I didn't miss the point (I think). He was doing the work of an electrician.
And whether or not he was a licensed electrician, he is still morally
responsible for the quality of his work. (Think Hamurabi.)

Actually, you *are* missing the important point, which is that it's
_not_his_fault_:

1) 245VAC is *not* a problem in a nominal 240VAC supply.
2) If the equipment is actually labelled 220V, and not 240V, it's *old*.
3) Equipment designed for 220VAC normally operates just fine on 240VAC.
4) If the wiring, or the voltage, were in any way to blame, the failure almost
certainly would have occurred long before it did. Four weeks after the fact, I
can't see how that could be laid at the feet of the guy that did the wiring,
licensed or not.

On Jul 5, 5:04*am, Andrew VK3BFA wrote:
On Jul 5, 4:40*pm, John E. wrote:



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.

Thanks.
--
John English

Tempting as it is to blame your Mr Bush for all the eveils of the
world, including my hens not laying, I would propose the following:
1.As noted, the main supply voltage is nominal, variations are normal
and to be expected.

Any reasonable design for the power supply should have defended the
controller board even if the voltage was further out of bounds than
the poster suggested.

That said: I don't think we can blame Bush for this because it didn't
burn down the whole shop in the process.

2.Possibly, if the machine was let stand for a while in the unpowered
position, and it was an old controller (and with a linear power
supply, it probably was,) then the electrolytics in the power supply
could have failed due high ESR, and then it lost regulation and fried
the board.

The capacitors could have also failed in the leaky and then exploding
manner. Having them suddenly go open as they flung their guts all
over the insides could have been the cause.

That said: I don't think we can blame Bush for this because it was
Hillary that swapped all the "N" and "Q" keys on the key boards in the
Whitehouse so it was likely her fault.

3.My humble opinion is to just mark write it off to bad luck.
Otherwise, get the lawyers involved for years and huge amounts of
money......

Andrew VK3BFA