Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

My lights and shop equipment are all multi-tap wired and are capable
on running on any of the voltages.

I do have some small bench top and hand held machines that require
110v single phase.

I have one lathe powered by a 200v three phase motor - I would be
willing to replace this motor, if it would seem to be an advantage to
go with one of the higher voltages for other reasons.

I have hopes of going to some newer machinery in the future, most /
all of it seems to be rated for 220v, but with the notation that it is
operable on 208.

Your help and advice on this is greatly appreciated. Thanks in
advance,

Jess

Jess wrote:

Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

If it's just a home shop do not get 440v.
You're out of the realm of do-it-yourself
electrical work and accidents involving 440
are *not* fun.

My lights and shop equipment are all multi-tap wired and are capable
on running on any of the voltages.

I do have some small bench top and hand held machines that require
110v single phase.

I have one lathe powered by a 200v three phase motor - I would be
willing to replace this motor, if it would seem to be an advantage to
go with one of the higher voltages for other reasons.

I have hopes of going to some newer machinery in the future, most /
all of it seems to be rated for 220v, but with the notation that it is
operable on 208.

Your help and advice on this is greatly appreciated. Thanks in
advance,

Jess

Peter Wiley wrote:
In article , Jim Stewart
wrote:


Jess wrote:


Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

If it's just a home shop do not get 440v.
You're out of the realm of do-it-yourself
electrical work and accidents involving 440
are *not* fun.


My shop is wired 415V 3 phase. Did it all myself with an inspection by
the electrical contractor before the sub board was 'hot'. Can't see
it'll kill you any deader than lower voltages. I did it all to code
because *I* was the one going to be using it.

First of all, I'm no expert and I'll certainly
defer to the pro electricians in the group.

That said, 440/480 is uniquely dangerous in it's
ability to sustain a plasma fire without tripping
upstream breakers. A screwdriver dropped onto
busbars can evolve into something that will burn
your arm off or worse.

I think the electrocution risk is substantially
greater than 240V as well.

Then again my single phase supply here in Aus is 240V, so I think our
general wiring standards are waaay tighter than yours. When I lived in
the USA a few years ago, at least, the general wiring standard,
frankly, sucked.

Part of the problem is that standards enforcement
is primarily a local issue. I agree that stuff
like using a clothes dryer ground lead to pull
current for the motor or lamp is pretty much
nonsense.

I wired my garage subpanel myself as well. When
I call the city inspector to sign it off, he said
"You must have done it yourself, it's too neat for
an electrician.

Get the supply you think is going to be most useful for the size motors
etc you're going to be running and do it to or above code requirements.


PDW

If you are in USA or Canada wire 120/208 three phase. If you need 440 , 480.
277 , 575 , 347 ?600 use step transformers. All your lighting and most of
your motors will work off of this system. Your utility company will have you
install a seven jaw 3 1/2 element meter to measure your single phase and
three phase loads. Try to keep away from demand metering, the penalties can
really sour a fun day in the shop if your instantaneous demands are high and
prolonged.Power factor is not something you want to have to monitor and
correct.
My two cents worth!

Pete



"Jess" wrote in message
...
Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

My lights and shop equipment are all multi-tap wired and are capable
on running on any of the voltages.

I do have some small bench top and hand held machines that require
110v single phase.

I have one lathe powered by a 200v three phase motor - I would be
willing to replace this motor, if it would seem to be an advantage to
go with one of the higher voltages for other reasons.

I have hopes of going to some newer machinery in the future, most /
all of it seems to be rated for 220v, but with the notation that it is
operable on 208.

Your help and advice on this is greatly appreciated. Thanks in
advance,

Jess

On Mon, 12 Sep 2005 14:28:25 -0700, Jim Stewart
wrote:


I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

If it's just a home shop do not get 440v.
You're out of the realm of do-it-yourself
electrical work and accidents involving 440
are *not* fun.


Brrrrrrrrr...no...440 is into the "fiery plasma ball exploding flaming
bits of molten metal in a grenade like sphere of hell" sort of thing.

220 would be cool.

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

"Jess" wrote in message
...
Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

I have three phase, and have had it as long as I've had a shop (since '67).
First shop was an open delta system, which is fine for light duty----no
large motors, say, under 7-1/2 hp.. I now have a 400 amp service, again,
delta. I had the option of 480, but didn't want to deal with the higher
voltage, even though one of my machines (a cylindrical universal grinder)
requires 480 volts. I have a transformer for that one machine.

The one negative is that with a delta service, you have a wild leg (208
volts, the B phase) that can't be used for 120V service. That's no big
deal, but it costs you one space out of three on your panel. You can use
the space for 240 volts single phase, however, so something like a welder or
water heater can occupy the otherwise unused space. If you select a
delta service (240 volts), be sure to keep that in mind so you size your
panel properly. The advantage of delta over wye (star) is the 240 volts
instead of 208. Motors will run cooler--although you're not supposed to be
sacrificing any power with the wye system. Dunno, I'm not an EE, nor an
electrician. I do know that a close friend had problems with some CNC
grinders when he moved to his new shop, equipped with 208 volts instead of
240.

Hope this helps more than it confuses.

Harold

In article , Jim Stewart
wrote:

Jess wrote:

Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

If it's just a home shop do not get 440v.
You're out of the realm of do-it-yourself
electrical work and accidents involving 440
are *not* fun.

My shop is wired 415V 3 phase. Did it all myself with an inspection by
the electrical contractor before the sub board was 'hot'. Can't see
it'll kill you any deader than lower voltages. I did it all to code
because *I* was the one going to be using it.

Then again my single phase supply here in Aus is 240V, so I think our
general wiring standards are waaay tighter than yours. When I lived in
the USA a few years ago, at least, the general wiring standard,
frankly, sucked.

Get the supply you think is going to be most useful for the size motors
etc you're going to be running and do it to or above code requirements.


PDW

Jess wrote:
Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

My lights and shop equipment are all multi-tap wired and are capable
on running on any of the voltages.

I do have some small bench top and hand held machines that require
110v single phase.

I have one lathe powered by a 200v three phase motor - I would be
willing to replace this motor, if it would seem to be an advantage to
go with one of the higher voltages for other reasons.

I have hopes of going to some newer machinery in the future, most /
all of it seems to be rated for 220v, but with the notation that it is
operable on 208.

Your help and advice on this is greatly appreciated. Thanks in
advance,

Jess

I'm going to agree with the folks recommending against the 480v. That's
the evil power, everyone I've ever discussed it with agrees. Another
angle is that you need top quality stuff for 480, you just don't want to
use used wire and plugs on it, where with 240 you can use stuff that's
less than absolutely perfect. A little carbon tracking in a plug, it'll
arc with 480v where it just doesn't seem to with 240.

If you're willing to buy all new stuff, there's the natural gain of
lower amperage draw with 480.. but it'll find any problems in your
wiring, etc. far quicker than 240v. Motor insulation is no problem, the
windings only see 240v either way, it's the plugs and wiring that's the
issue.

John

On Mon, 12 Sep 2005 15:51:38 -0500, Jess
wrote:

Hi all,

I would like some help / advice in outfitting my shop.

My question is, which voltage should I specify - and why?

Update:

Thanks for all the help so far.
OK, the 440v is out. Any future 400+v requirements will be avoided or
met with my own transformer and new top notch gear downstream.

Delta vs Wye?, 208 vs 240 ?
It seems like there are some definite compromises there.
In particular - whether or not you have 110v single and 240v single
available, and whether you have three well balanced legs? (if I
understand correctly).

Any other additions to the delta / wye 208 /240 debate would be
greatly appreciated.

Thanks again for all the help.
Jess

In article , Jim Stewart
wrote:

Peter Wiley wrote:
In article , Jim Stewart
wrote:


Jess wrote:


Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

If it's just a home shop do not get 440v.
You're out of the realm of do-it-yourself
electrical work and accidents involving 440
are *not* fun.


My shop is wired 415V 3 phase. Did it all myself with an inspection by
the electrical contractor before the sub board was 'hot'. Can't see
it'll kill you any deader than lower voltages. I did it all to code
because *I* was the one going to be using it.

First of all, I'm no expert and I'll certainly
defer to the pro electricians in the group.

That said, 440/480 is uniquely dangerous in it's
ability to sustain a plasma fire without tripping
upstream breakers. A screwdriver dropped onto
busbars can evolve into something that will burn
your arm off or worse.

I think the electrocution risk is substantially
greater than 240V as well.

I suspect the 440 you're referring to is a different animal, then. Our
415 3 phase is pretty common, used a lot for domestic air conditioners
and the like. Country places off 3 phase are the only sites I've ever
come across with 480V and it's single phase, not 3.

Then again my single phase supply here in Aus is 240V, so I think our
general wiring standards are waaay tighter than yours. When I lived in
the USA a few years ago, at least, the general wiring standard,
frankly, sucked.

Part of the problem is that standards enforcement
is primarily a local issue. I agree that stuff
like using a clothes dryer ground lead to pull
current for the motor or lamp is pretty much
nonsense.

I wired my garage subpanel myself as well. When
I call the city inspector to sign it off, he said
"You must have done it yourself, it's too neat for
an electrician.

Heh. That's exactly what the inspector said to me when he checked my
last place. It doesn't take *that* much longer to do it neatly than
sloppily.

PDW

Gunner Asch wrote:




Brrrrrrrrr...no...440 is into the "fiery plasma ball exploding flaming
bits of molten metal in a grenade like sphere of hell" sort of thing.

220 would be cool.



Uh 220, and even 120 will do that as well. It's not the voltage. but
the available current.
jk

Jim Stewart wrote:



My shop is wired 415V 3 phase. Did it all myself with an inspection by
the electrical contractor before the sub board was 'hot'. Can't see
it'll kill you any deader than lower voltages. I did it all to code
because *I* was the one going to be using it.

First of all, I'm no expert and I'll certainly
defer to the pro electricians in the group.

That said, 440/480 is uniquely dangerous in it's
ability to sustain a plasma fire without tripping
upstream breakers.


Not so at all


A screwdriver dropped onto
busbars can evolve into something that will burn
your arm off or worse.

So can 25V if you work it right, but 440/480 is no worse that 240 for
sustaining a phase to phase arc.



I think the electrocution risk is substantially
greater than 240V as well.



PDW

jk

"jk" wrote in message
...
Jim Stewart wrote:



My shop is wired 415V 3 phase. Did it all myself with an inspection by
the electrical contractor before the sub board was 'hot'. Can't see
it'll kill you any deader than lower voltages. I did it all to code
because *I* was the one going to be using it.

First of all, I'm no expert and I'll certainly
defer to the pro electricians in the group.

That said, 440/480 is uniquely dangerous in it's
ability to sustain a plasma fire without tripping
upstream breakers.


Not so at all

I think the previous statement is likely correct. Given adequate current
supply, voltage determines arcing ability.
I don't know if 440 is the magic number, but certainly the higher the
voltage, the more likely this ability becomes.



A screwdriver dropped onto
busbars can evolve into something that will burn
your arm off or worse.

So can 25V if you work it right, but 440/480 is no worse that 240 for
sustaining a phase to phase arc.

440 is worse for everything safety-wise. P=I^R=E^2/R, so the power capacity
of higher voltage is quite significantly higher.
But higher voltage also lowers power losses in wire, increasing motor
efficiency. Which is why it's used in heavy duty applications.
I've seen 208 in a shorted 3 ph plug sear the skin off a whole palm of a
hand; imagine 440!




I think the electrocution risk is substantially
greater than 240V as well.

Proly 4x as great.
------------------
Mr. P.V.'d,
formerly Droll Troll





PDW

jk

Jess wrote:

On Mon, 12 Sep 2005 15:51:38 -0500, Jess
wrote:

Hi all,

I would like some help / advice in outfitting my shop.

My question is, which voltage should I specify - and why?

Update:

Thanks for all the help so far.
OK, the 440v is out. Any future 400+v requirements will be avoided or
met with my own transformer and new top notch gear downstream.

Delta vs Wye?, 208 vs 240 ?
It seems like there are some definite compromises there.
In particular - whether or not you have 110v single and 240v single
available, and whether you have three well balanced legs? (if I
understand correctly).

Any other additions to the delta / wye 208 /240 debate would be
greatly appreciated.

Thanks again for all the help.
Jess

Here's my opinion, for what it's worth, applied to a non-commercial shop
in the U.S. The problem with 480V is not so much a safety issue (and
the real danger is the available fault current more than the voltage) as
one of economics. 480 volt wiring methods are the same as with lower
voltages, but the power panels and breakers tend to be more costly and
you'll need to provide for 120/240 single phase loads with a separate
panel and transformer on a branch circuit. Unless you have several
motors in the greater than 10 to 15 hp range rule 480V services out from
the start.

120/208 wye service is not really appropriate for a shop either, this
service is good for lighting but not so good for motor loads, save it
for the next strip mall or office building you build. It's 208 because
that's what your stuck with when you set out to get 120 volts phase to
neutral in a wye connection.

For a hobby or small commercial shop go with a 240v center tapped delta
service. You get 240 three phase and 240/120 single phase all out of
one panel. Yes, you'll end up with a few unused slots in the panel due
to the 'high leg', but who cares. If it's a mystery as to which phases
supply which voltages to neutral don't even take the panel cover screws
out and leave it to someone who knows, but it's really no big deal. The
power company, at least around here, prefers this service as it
generally has a lower installed cost, they can get by with just two
transformers and wire it open delta. To you, the end user, it generally
won't matter. You'll have extra work to due for single voltage 480V
motors, but most machine tool motors are of the dual voltage variety
anyway. I'm hard pressed for a valid reason to even consider another
service for a small shop.

Regards
Paul
--
-----------------------------------------
It's a Linux world....well, it oughta be.
-----------------------------------------

120/208 wye service is not really appropriate for a shop either, this

My father was an electrician and I use to help him when I was a kid.
At that time I thought 208 was the best because you could easily
get 120 for lights and run real motors on three phase. Now I am
not very fond of 208.

You should check your machines to see if the motors will actually
run on 208. I suspect that many (or most) of than will not.

In my home shop I run all my 3 phase motors with VFDs. I hate 208
volt motors because they do not work well with a VFD and tend
to over heat because they are getting 240V instead of 208V.

I have experimented with VFD parameters and managed to program
a Teco drive to put out 208 instead of 240. My 1/2HP surface
grinder works ok this way, but the 1HP motor on my rockwell lathe
didn't like it much so I had to buy a new motor.

chuck

On Wed, 14 Sep 2005 17:44:13 -0700, jk wrote:

Gunner Asch wrote:




Brrrrrrrrr...no...440 is into the "fiery plasma ball exploding flaming
bits of molten metal in a grenade like sphere of hell" sort of thing.

220 would be cool.



Uh 220, and even 120 will do that as well. It's not the voltage. but
the available current.
jk

True..but how often have you seen 220 do that with a carbon track on a
plug?

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

Paul Batozech wrote:
Jess wrote:

On Mon, 12 Sep 2005 15:51:38 -0500, Jess
wrote:

Hi all,

I would like some help / advice in outfitting my shop.

My question is, which voltage should I specify - and why?

Update:

Thanks for all the help so far.
OK, the 440v is out. Any future 400+v requirements will be avoided
or met with my own transformer and new top notch gear downstream.

Delta vs Wye?, 208 vs 240 ?
It seems like there are some definite compromises there.
In particular - whether or not you have 110v single and 240v single
available, and whether you have three well balanced legs? (if I
understand correctly).

Any other additions to the delta / wye 208 /240 debate would be
greatly appreciated.

Thanks again for all the help.
Jess

Here's my opinion, for what it's worth, applied to a non-commercial
shop in the U.S. The problem with 480V is not so much a safety issue
(and the real danger is the available fault current more than the
voltage) as one of economics. 480 volt wiring methods are the same
as with lower voltages, but the power panels and breakers tend to be
more costly and you'll need to provide for 120/240 single phase loads
with a separate panel and transformer on a branch circuit. Unless
you have several motors in the greater than 10 to 15 hp range rule
480V services out from the start.


I have a 480 volt service to my shop and house. The main down side like
mentioned above is the transformer to supply the lower voltage power. The
problem with the transformer is it's cost of operation!! They suck lots of
power just sitting there running! Having said that though, I would still
run the same system for my shop if I was going to reinstall it today.

William...

"William" wrote in message
...
snip-----


I have a 480 volt service to my shop and house. The main down side like
mentioned above is the transformer to supply the lower voltage power. The
problem with the transformer is it's cost of operation!! They suck lots
of
power just sitting there running! Having said that though, I would still
run the same system for my shop if I was going to reinstall it today.

William...



I've given the idling transformer some thought, but I'm in the opposite
position. I have only one machine that will run on 480 volts (can't be run
lower), so my 3 phase delta 240 volt system is perfect for my application.
The 480 volt transformer for the one machine will be kept turned off unless
the machine is in service. That way I'm not heating the shop
unnecessarily.

I avoided the lost spaces in my 3 phase panel by installing a single phase
and a three phase panel. the shop is large, so it justified both panels.
Only the 3 phase is on a demand meter, so I minimize my chances of paying
high prices for power. On the other hand, I do have two power bills, but
that was inevitable if I wanted three phase service. Policy at our Public
Utility District is that 3 phase service is considered industrial------not
residential-----so you have to have different metering. 3 phase is always
on a demand meter here.

No way was I going to install a wye system.

Harold

"Proctologically Violated©®" wrote:


"jk" wrote in message
.. .
Jim Stewart wrote:
That said, 440/480 is uniquely dangerous in it's
ability to sustain a plasma fire without tripping
upstream breakers.

Not so at all

I think the previous statement is likely correct. Given adequate current
supply, voltage determines arcing ability.
I don't know if 440 is the magic number, but certainly the higher the
voltage, the more likely this ability becomes.

The generally considered (such that there is one) "Magic number" is
100 V to sustain an arc in air.

400 some odd volts is in no way "uniquely dangerous". Yes it is more
dangerous than 200 some odd, and less so than 600 some odd or 4160.



440 is worse for everything safety-wise. P=I^R=E^2/R, so the power capacity
of higher voltage is quite significantly higher.

Only if you ASSUME that the available fault current is the same, which
in general it is not.

But higher voltage also lowers power losses in wire, increasing motor
efficiency. Which is why it's used in heavy duty applications.
I've seen 208 in a shorted 3 ph plug sear the skin off a whole palm of a
hand; imagine 440!

That is based solely on arc currents, distance and exposure time, and
the chances are better (if not good) that you have a current limiting
device upstream at 440.

I think the electrocution risk is substantially
greater than 240V as well.

Proly 4x as great.
------------------

Probably and provably not. Far and away the greatest number of
electrocutions occurs from 120 V circuits in the US. Yes the higher
voltage can punch through the skin barrier easier, but far more people
treat 120 in a very cavalier fashion.
jk

Gunner wrote:


True..but how often have you seen 220 do that with a carbon track on a
plug?

Gunner


Just as often as I have seen it happen on 480.

jk

Let the record show that Gunner Asch wrote back on
Tue, 13 Sep 2005 05:21:52 GMT in rec.crafts.metalworking :
On Mon, 12 Sep 2005 14:28:25 -0700, Jim Stewart
wrote:


I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

If it's just a home shop do not get 440v.
You're out of the realm of do-it-yourself
electrical work and accidents involving 440
are *not* fun.


Brrrrrrrrr...no...440 is into the "fiery plasma ball exploding flaming
bits of molten metal in a grenade like sphere of hell" sort of thing.

So, like, you're saying I should let my brother-in-law make any
adjustments?

220 would be cool.

When I was younger, I lived in Madrid, and in the new apartment, we
were getting a step-down transformer installed to convert the local (220
volts) to American appliance (110 VAC). Heard the "zot" and kind of saw the
flash of the short, definitely saw the electrician fall on his butt from
the shock. He wasn't too hurt, but he utter those immortal words to live
by:
"I didn't think that was going to work."

Word.

tschus
pyotr

--
pyotr filipivich.
as an explaination for the decline in the US's tech edge, James
Niccol wrote "It used to be that the USA was pretty good at
producing stuff teenaged boys could lose a finger or two playing with."

On Thu, 15 Sep 2005 18:16:45 -0700, jk wrote:

"Proctologically Violated©®" wrote:

I think the electrocution risk [of 480 volts] is substantially
greater than 240V as well.

Proly 4x as great.
------------------

Probably and provably not. Far and away the greatest number of
electrocutions occurs from 120 V circuits in the US. Yes the higher
voltage can punch through the skin barrier easier, but far more people
treat 120 in a very cavalier fashion.

Wouldn't it also be a factor that 120 volts is much more commonly
available (and especially around those without much knowledge of
electricity) than 480 volts?

Since I'm posting on the subject of 3 phase power from the utility co.
I'm curious if 3 phase power is more or less expensive per kilowatt hour
than single phase. Is it even a valid comparison?

Actually, the open circuit voltage in arc welders is about 80V, and the
voltage at sustainable arc is about 25V, iirc.
There is no strict magic number, because arcing ability is highly dependent
on geomety, w/ sharp points arcing much more easily than flat surfaces--ie,
higher electric field intensity at cusps.

The salient point is, the higher the voltage, the more arcing you can have.

If you're going to throw in the upstream safety devices w/ 440, you're
changing the game.
Majority of electrocutions at 120V?? Mebbe cuz 300,000,000 people have 120V
wall outlets??

*Per capita*, proly by far the greatest number of electrocutions occur in TV
repairmen, at least back in the day when TVs were fixable (tubes,
donchaknow). 10,000 V.
Oh yeah, and high-tension linemen.
----------------------------
Mr. P.V.'d
formerly Droll Troll
"jk" wrote in message
...
"Proctologically Violated©®" wrote:


"jk" wrote in message
. ..
Jim Stewart wrote:
That said, 440/480 is uniquely dangerous in it's
ability to sustain a plasma fire without tripping
upstream breakers.

Not so at all

I think the previous statement is likely correct. Given adequate current
supply, voltage determines arcing ability.
I don't know if 440 is the magic number, but certainly the higher the
voltage, the more likely this ability becomes.

The generally considered (such that there is one) "Magic number" is
100 V to sustain an arc in air.

400 some odd volts is in no way "uniquely dangerous". Yes it is more
dangerous than 200 some odd, and less so than 600 some odd or 4160.



440 is worse for everything safety-wise. P=I^R=E^2/R, so the power
capacity
of higher voltage is quite significantly higher.

Only if you ASSUME that the available fault current is the same, which
in general it is not.

But higher voltage also lowers power losses in wire, increasing motor
efficiency. Which is why it's used in heavy duty applications.
I've seen 208 in a shorted 3 ph plug sear the skin off a whole palm of a
hand; imagine 440!

That is based solely on arc currents, distance and exposure time, and
the chances are better (if not good) that you have a current limiting
device upstream at 440.

I think the electrocution risk is substantially
greater than 240V as well.

Proly 4x as great.
------------------

Probably and provably not. Far and away the greatest number of
electrocutions occurs from 120 V circuits in the US. Yes the higher
voltage can punch through the skin barrier easier, but far more people
treat 120 in a very cavalier fashion.
jk

On Thu, 15 Sep 2005 12:04:56 -0700, Harold and Susan Vordos wrote:

3 phase is always on a demand meter here.

I've seen the term "demand metering" mentioned here several times
and have gleaned that it can be expensive for some reason. What is
demand metering and why is it more expensive than other types of
metering?

(My dream is to sell my house when I retire and live in a shop
which will have 3 phase power from the util. co.)

On Thu, 15 Sep 2005 18:21:44 -0700, jk wrote:

Gunner wrote:


True..but how often have you seen 220 do that with a carbon track on a
plug?

Gunner


Just as often as I have seen it happen on 480.

jk

I guess I must be unusual then.

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

"Artemia Salina" wrote in message
news
On Thu, 15 Sep 2005 12:04:56 -0700, Harold and Susan Vordos wrote:

3 phase is always on a demand meter here.

I've seen the term "demand metering" mentioned here several times
and have gleaned that it can be expensive for some reason. What is
demand metering and why is it more expensive than other types of
metering?

(My dream is to sell my house when I retire and live in a shop
which will have 3 phase power from the util. co.)

As I understand it, the meter monitors the sustained gross current drawn for
a given period of time. If you go over a prescribed amperage (here, it's
50 kw), you are charged a higher amount for all of your consumption for that
billing period. You must sustain the draw for something like 15 minutes
in order to set the meter, so simply starting a large motor, for example,
doesn't reset the meter. Because I don't have my induction furnace in
operation yet (it's a 50 kw unit itself), I haven't come close to exceeding
the demand.

Harold

Harold and Susan Vordos wrote:
"Artemia Salina" wrote in message
news
On Thu, 15 Sep 2005 12:04:56 -0700, Harold and Susan Vordos wrote:


3 phase is always on a demand meter here.

I've seen the term "demand metering" mentioned here several times
and have gleaned that it can be expensive for some reason. What is
demand metering and why is it more expensive than other types of
metering?

(My dream is to sell my house when I retire and live in a shop
which will have 3 phase power from the util. co.)


As I understand it, the meter monitors the sustained gross current drawn for
a given period of time. If you go over a prescribed amperage (here, it's
50 kw), you are charged a higher amount for all of your consumption for that
billing period. You must sustain the draw for something like 15 minutes
in order to set the meter, so simply starting a large motor, for example,
doesn't reset the meter. Because I don't have my induction furnace in
operation yet (it's a 50 kw unit itself), I haven't come close to exceeding
the demand.

Right.

The short-term reason is to reduce peaks
so that the utility doesn't have to bring
another generator on line or buy power
from another utility.

The long-term reason is so that the utility
doesn't have to make capital investments
in lines and plant that will only be used
a couple of hours a day.

The utilities have taken it a step further
in some areas. They will give certain industrial
customers a discount on all their power if
they agree to cut their load upon request.

Jim Stewart wrote:

Harold and Susan Vordos wrote:
"Artemia Salina" wrote in message
news
On Thu, 15 Sep 2005 12:04:56 -0700, Harold and Susan Vordos wrote:


3 phase is always on a demand meter here.

I've seen the term "demand metering" mentioned here several times
and have gleaned that it can be expensive for some reason. What is
demand metering and why is it more expensive than other types of
metering?

(My dream is to sell my house when I retire and live in a shop
which will have 3 phase power from the util. co.)


As I understand it, the meter monitors the sustained gross current drawn for
a given period of time. If you go over a prescribed amperage (here, it's
50 kw), you are charged a higher amount for all of your consumption for that
billing period. You must sustain the draw for something like 15 minutes
in order to set the meter, so simply starting a large motor, for example,
doesn't reset the meter. Because I don't have my induction furnace in
operation yet (it's a 50 kw unit itself), I haven't come close to exceeding
the demand.

Right.

The short-term reason is to reduce peaks
so that the utility doesn't have to bring
another generator on line or buy power
from another utility.

The long-term reason is so that the utility
doesn't have to make capital investments
in lines and plant that will only be used
a couple of hours a day.

The utilities have taken it a step further
in some areas. They will give certain industrial
customers a discount on all their power if
they agree to cut their load upon request.




The meter will measure the peak current drawn from the line. Over a
certain peak current you pay a demand rate in addition to the actual
usage. The demand billing is to pay for the extra reserve and the cost
of maintaining the larger feeder systems used to supply you the higher
peak current. The electric company has a formula for calculating the
demand rate. Every company is different in their calculations, but in
any event you do not want to start too many motors at the same time.

John

john wrote:
Jim Stewart wrote:
Harold and Susan Vordos wrote:

Thanks guys. I get it now.

Harold and Susan Vordos wrote:
"William" wrote in message
...
snip-----


I have a 480 volt service to my shop and house. The main down side
like mentioned above is the transformer to supply the lower voltage
power. The problem with the transformer is it's cost of operation!!
They suck lots of power just sitting there running! Having said
that though, I would still run the same system for my shop if I was
going to reinstall it today.

William...



I've given the idling transformer some thought, but I'm in the
opposite position. I have only one machine that will run on 480
volts (can't be run lower), so my 3 phase delta 240 volt system is
perfect for my application. The 480 volt transformer for the one
machine will be kept turned off unless the machine is in service.
That way I'm not heating the shop unnecessarily.



The idle current form a small transformer that you run one machine off will
not be that bad . My problem is that I needed/wanted to have 200 amps of
power on the lower voltage (120/208) in my case derived from my single 600
amp 480/277 feed. since it's on my side of the meter it's covered by the
NEC and that requires a 75kva transformer for the 200 amps even though I
will NEVER pull 200 amps through it! In fact the Utility co feeds the whole
600 amp service with 3, 25kva cans on the pole ( at my request they will
replace them with larger ones if I want/need them but they charge a min fee
based on the size of the cans so the smaller ones work for me!)


I avoided the lost spaces in my 3 phase panel by installing a single
phase and a three phase panel. the shop is large, so it justified
both panels. Only the 3 phase is on a demand meter, so I minimize my
chances of paying high prices for power. On the other hand, I do
have two power bills, but that was inevitable if I wanted three phase
service. Policy at our Public Utility District is that 3 phase
service is considered industrial------not residential-----so you have
to have different metering. 3 phase is always on a demand meter here.


My system is all demand metered ( and only one bill that way) BUT, at the
magic "75kva average over a 15 min interval " they kick in the demand charge
( if during the 3 summer / 3 winter peak months) You can BET I will never
let that happen as it's CHA CHING!! if it does. At almost $15.00 per KVA +
the KW charge for the whole month. The 75 kva is a lot of power though and
I don't think I will exceed that.


No way was I going to install a wye system.

I wanted the wye and the 277 volts for the HID lighting is great. The cost
of Cu wire is out of sight and I can run most of my machines off 12 gauge
wire if I want. I only have 2 machines that didn't like the 480 volts, and
one runs fine on the 208 and the other (the blade welder for the band saw)
would have probably worked ok but I picked up a single phase 480volt to 240
volt transformer for cheep for the times I have to use that unit.

William....

jk wrote:
Gunner wrote:



True..but how often have you seen 220 do that with a carbon track on a
plug?

Gunner



Just as often as I have seen it happen on 480.

jk

I've seen it plenty of times on 480, can't remember ever seeing it on 240.

John

"JohnM" wrote in message
...
jk wrote:
Gunner wrote:



True..but how often have you seen 220 do that with a carbon track on a
plug?

Gunner



Just as often as I have seen it happen on 480.

jk

I've seen it plenty of times on 480, can't remember ever seeing it on 240.

John

That makes sense to me. It's absurd to assume that the voltage makes no
difference. Given a high enough voltage, an arc can generate when there
are no proper conductors in the path. After all, aren't most insulators,
for the most part, simply not good conductors? With enough pressure
(voltage) anything will conduct------even glass. That being the case, it
stands to reason that as the voltage is lowered, so is the propensity for
arcing.

Harold

Yep - the car battery does it nicely.

Martin
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder



Harold and Susan Vordos wrote:
"JohnM" wrote in message
...

jk wrote:

Gunner wrote:




True..but how often have you seen 220 do that with a carbon track on a
plug?

Gunner



Just as often as I have seen it happen on 480.

jk

I've seen it plenty of times on 480, can't remember ever seeing it on 240.

John


That makes sense to me. It's absurd to assume that the voltage makes no
difference. Given a high enough voltage, an arc can generate when there
are no proper conductors in the path. After all, aren't most insulators,
for the most part, simply not good conductors? With enough pressure
(voltage) anything will conduct------even glass. That being the case, it
stands to reason that as the voltage is lowered, so is the propensity for
arcing.

Harold



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Artemia Salina wrote:

On Thu, 15 Sep 2005 18:16:45 -0700, jk wrote:



Wouldn't it also be a factor that 120 volts is much more commonly
available (and especially around those without much knowledge of
electricity) than 480 volts?

Absolutely

Since I'm posting on the subject of 3 phase power from the utility co.
I'm curious if 3 phase power is more or less expensive per kilowatt hour
than single phase. Is it even a valid comparison?

It depends entirely on your rate schedule. Either could be cheaper.
I have two services, I pay significantly less per kwh for one, than I
do for the other, even though both are 120/240 100A services.


jk

On Mon, 12 Sep 2005 15:51:38 -0500, Jess
wrote:

Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

If you have any 480V loads to run and you can get a 480V 3Ph feed
from the utility without a hassle or a huge price penalty compared to
240V 3Ph, it's always far simpler to drop a 480V feed down to 240V for
most of your loads with a cheap used transformer than it is to boost a
240V feed up to 480V.

And a 200A @ 480V feed goes a whole lot further. But as has been
pointed out, 480V demands some serious respect because it will reach
out and bite you hard, and things tend to "blow up reel gud" ;-) with
very little provocation.

You put in the 480V meter section and main, a small (12 or 18
position) 480V distribution breaker panel to feed any machines that
must be run at 480V, or fused safety switches - and be sure to run it
in as 4-wire with a neutral in case you ever need 277V for lights.
Then you install your 480V-240V transformer, and a larger (and much
cheaper) 240V 3Ph panel for the bulk of your equipment.

If you want to run 277V lighting in a large shop, pay a bit more for
the light fixtures with individual fuses inside. Without them, one
ballast in a long string of lights goes bad and grounds out, and you
go nuts opening every single stupid fixture to find the culprit. Or
you split the circuit and test, and hope the circuit breaker lives
through the repeated short-circuit torture test. BT, DT...

I do have some small bench top and hand held machines that require
110v single phase.

Run a separate "lights and plugs" feed out to the shop building from
your house's 120-240V 1Ph panel feed, or leave the existing one hooked
up. This way, you can kill all the shop power at the 3Ph Main to work
on it, or just to kill the parasitic loads from the transformers and
keep "unauthorized personnel" from messing with your toys, and not be
in the dark.

With that power coming in on a totally separate feeder you keep the
motor start surges and welder spikes away from the more sensitive
gear. And no lights dimming when you hit the big switches.

Also, see mentions of demand metering and higher rates for
'commercial power' mentioned elsewhere - that way the lights, furnace
blower, computers, clocks, and other incidental loads that tend to add
up fast are being metered at the residential rate.

I have one lathe powered by a 200v three phase motor - I would be
willing to replace this motor, if it would seem to be an advantage to
go with one of the higher voltages for other reasons.

Consider getting three buck-boost transformers to drop a 240V or
208V line to 200V, depending on the price it's probably cheaper than a
new motor. And you can use some ridiculously small and cheap
transformers for that, even when buying new.

I have hopes of going to some newer machinery in the future, most /
all of it seems to be rated for 220v, but with the notation that it is
operable on 208.

A lot of equipment does both 208V and 240V, the current is slightly
higher at 208V. Makes it easier to wire up small industrial parks at
208V without people constantly making "Oopsies" hooking up 120V stuff
to the ~190V 'High Leg' of a 120/240V Delta service.

If I had my way, ALL houses would be able to get either 120/208V Wye
or 120/240V Delta feeds on demand - Just putting the largest motor
loads like air conditioning/heat pump compressors on 3-phase increases
the energy efficiency enough to make for a short payback period.

"But that will never happen - It would simply make too much sense."
(© BLB)

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

Hi Jess
One other thing you might want to consider, is if your shop is already wired
for 120/240 single phase the insulation on the present wire is probably not
rated for 480 service. 480 service requires wire with 600 volt insulation.
This would not be a consideration with 240 three service.
Travis
"Jess" wrote in message
...
Hi all,

I would like some help / advice in outfitting my shop.

For the first time in my metalworking home shop, I am able to get 3
phase service from the local power company.

In the past, I have always used a 3 phase rotary converter that I
built with the help of the group here - special thanks to Fitch and
Bob Campbell.

My question is, which voltage should I specify - and why?

I can get 208v, 220v or 440v.

What are the pros and cons, if any, between the choices?

My lights and shop equipment are all multi-tap wired and are capable
on running on any of the voltages.

I do have some small bench top and hand held machines that require
110v single phase.

I have one lathe powered by a 200v three phase motor - I would be
willing to replace this motor, if it would seem to be an advantage to
go with one of the higher voltages for other reasons.

I have hopes of going to some newer machinery in the future, most /
all of it seems to be rated for 220v, but with the notation that it is
operable on 208.

Your help and advice on this is greatly appreciated. Thanks in
advance,

Jess

For a hobby or small commercial shop go with a 240v center tapped delta
service. You get 240 three phase and 240/120 single phase all out of
one panel. Yes, you'll end up with a few unused slots in the panel due
to the 'high leg', but who cares. If it's a mystery as to which phases
supply which voltages to neutral don't even take the panel cover screws
out and leave it to someone who knows, but it's really no big deal. The
power company, at least around here, prefers this service as it
generally has a lower installed cost, they can get by with just two
transformers and wire it open delta. To you, the end user, it generally
won't matter. You'll have extra work to due for single voltage 480V
motors, but most machine tool motors are of the dual voltage variety
anyway. I'm hard pressed for a valid reason to even consider another
service for a small shop.

You dont' mention if this is an additional service or a replacement
service. I had three phase installed a few years ago. It was a
replacement service. I went with 240V center tapped delta. It's the
way to go in my opionion. It will maintain all of your single phase
service with no(minimal) changes. You will gain "true" three phase.
Yes, there is a wild leg that needs to be kept in mind when considering
single phase loads. It's not really a big deal.

Check with your power provider. They will have a PE on staff that can
answer any questions. They can tell you what they will do, and what
expense it may be to you. Going to 240V 3ph cost me nothing for
installation. 208 or 480 would have been a minimal fee, but would
have required other "local" infrastructure changes to accomodate.

As many have suggested, stay away from 480V power. It steps things up
to a realm where you NEED to know exactly what you are doing or you
will hurt/kill yourself/others. It will also increase the expense of
equipment/materials. Everything will need to be 600V rated.

JW