In article , dpb wrote:
Doug Miller wrote:
In article , "Stephen M"
wrote:

220 - 10/3...just in case you need it some day.

We've had that discussion here before. :-)

There's *no* reason to use 3-conductor cable for 240V power tools. It's just
unnecessary expense. Three-conductor cable is needed for combined 240/120
loads such as a range or a dryer, that have 240V heating elements and 120V
motors and/or control circuits. A power tool with a 240V motor needs only
two-conductor cable; there isn't even anything to attach the third conductor
to, if it's present.

I have seen (but _very_ few (well, actually, precisely two ) --don't
know of any current-day that do) a couple of planers that used that as
well -- the main feed/cutterhead motor was 220V while the table lift and
an auxiliary sharpening attachment were 110V. Fella' in a shop in VA
had them. But certainly I'm unaware of anything currently on the market
set up that way.

Well, yes, as always, the requirements of any specific tool or appliance trump
"general rules". Interesting, though -- I didn't know anything of the sort had
ever been produced. Wonder if some of that might have been aftermarket mods?

If you want to plan for "in case you need it some day" it's better to not
run cables at all, but instead pull individual conductors through conduit:
pull what you need now, now; pull what you need later, later.

That's not bad advice, either...


--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Chris Friesen wrote:
Lew Hodgett wrote:

Chris Friesen wrote:
What's the point of an insulated ground?

It allows the entire distribution system to be grounded at the service
entrance point.

Single point grounding eliminates "Ground Loops" which can be quite
nasty.


I'm aware of ground loops. What does this have to do with an insulated
ground bus in a subpanel?

In my panel for instance, the ground bus is bonded to the panel, which
is in turn grounded via a conductor going back to the main panel. As
you mentioned, the entire system is grounded at the service entrance.

Chris


The resulting ground loop (parallel neutral current paths) will allow
dangerous objectionable current to flow onto metal parts of the
electrical installation (and onto metal piping and structural steel).

Source: http://ecmweb.com/mag/electric_groun...g_5/index.html

--
Jack Novak
Buffalo, NY - USA

Doug Miller wrote:
In article , dpb wrote:
Doug Miller wrote:
In article , "Stephen M"
wrote:
220 - 10/3...just in case you need it some day.
We've had that discussion here before. :-)

There's *no* reason to use 3-conductor cable for 240V power tools. It's just
unnecessary expense. Three-conductor cable is needed for combined 240/120
loads such as a range or a dryer, that have 240V heating elements and 120V
motors and/or control circuits. A power tool with a 240V motor needs only
two-conductor cable; there isn't even anything to attach the third conductor
to, if it's present.
I have seen (but _very_ few (well, actually, precisely two ) --don't
know of any current-day that do) a couple of planers that used that as
well -- the main feed/cutterhead motor was 220V while the table lift and
an auxiliary sharpening attachment were 110V. Fella' in a shop in VA
had them. But certainly I'm unaware of anything currently on the market
set up that way.
....

I believe these were factory jobs -- I've wished more than once I had
"bought'en" one of them from Eddie when he was selling them as he was
enlarging his shop, but $500 was a _lot_ of money back then and I was
just out of school so the $150 for the small shaper and 6" Rockwell
jointer was all I could manage at the time.

As I recall, everything looked to match and the controls were all
integral to the machine so I don't think it was an add-on. But I was
young and pretty new to stuff at the time so didn't stick w/ me what
they really were. Somebody long gone from the business now, I'm sure.
They were a nondescript gray, darker than Rockwell so no real clue to
try to match up like a recognizable PM green or some such.

He said he had bought'en them from a factory auction somewhere in PA --
they had had a production line of 25 of them -- 5 rows of 5 in line.
Started at one end w/ rough stock, came out at the other with their
surfaced/thicknessed stock for the sawyers on the other. They had
replaced the 25 machines/50 employees with 2 large planers and a wide
belt sander and five guys. About 1969/1970 when I met Eddie by
answering his classified ad. He had had the machines 2-3 years at that
point. I'd guess they were at least 20 years old if a day, probably
closer to 30 then...

--

In article 0s9ni.4506$4J4.3563@trndny05, Nova wrote:
Chris Friesen wrote:
Lew Hodgett wrote:

Chris Friesen wrote:
What's the point of an insulated ground?

It allows the entire distribution system to be grounded at the service
entrance point.

Single point grounding eliminates "Ground Loops" which can be quite
nasty.

I'm aware of ground loops. What does this have to do with an insulated
ground bus in a subpanel?

In my panel for instance, the ground bus is bonded to the panel, which
is in turn grounded via a conductor going back to the main panel. As
you mentioned, the entire system is grounded at the service entrance.

The resulting ground loop (parallel neutral current paths) will allow
dangerous objectionable current to flow onto metal parts of the
electrical installation (and onto metal piping and structural steel).

*What* "resulting ground loop"?

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

On Tue, 17 Jul 2007 20:10:02 GMT, (Doug Miller)
wrote:


snipped a bunch

Thanks, I think I understand both the theory and the mechanics.

If I want to have a 60 AMP subpanel, one method would be:

Buy a low cost package service entrance panel making sure what joins
the nuetral and ground buses is removable, remove the tie between the
nuetral and ground buses, make sure the ground bus is bonded to the
panel, replace the existing main breaker (which will probably be 100
amp or greater depending on the panel capacity) with a 60Amp main
breaker, and I'm there?

all the above assuming I have the properly sized, type and
appropriately run conductors from my main panel on a 60 AMP branch
circuit.

Frank

In article , Frank Boettcher wrote:
On Tue, 17 Jul 2007 20:10:02 GMT, (Doug Miller)
wrote:


snipped a bunch

Thanks, I think I understand both the theory and the mechanics.

Didn't mean to suggest that you didn't, Frank - sorry if I gave that
impression. I just wanted to correct the misstatements flying around, and
affirm that your understanding is the correct one.

If I want to have a 60 AMP subpanel, one method would be:

Buy a low cost package service entrance panel making sure what joins
the nuetral and ground buses is removable, remove the tie between the
nuetral and ground buses, make sure the ground bus is bonded to the
panel, replace the existing main breaker (which will probably be 100
amp or greater depending on the panel capacity) with a 60Amp main
breaker, and I'm there?

Bingo!

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Frank Boettcher wrote:

Again, goes against everything I've read and instinctively know to be
true. Without the bond, the subpanel panel itself is not grounded and
it has to be.

Mea Culpa, Mea Culpa, Thank you for being my editor.

That's what happens when you engage fingers before brain.

My previous post is in error as noted by Frank.

The sub panel gets a ground bar with the panel tub (enclosure) bonded
to it with the bonding strap and an insulated neutral bus that then
gets carried back to the service entrance panel.


Sorry for the confusion.

Lew

Frank Boettcher wrote:

If I want to have a 60 AMP subpanel, one method would be:

...replace the existing main breaker (which will probably be 100
amp or greater depending on the panel capacity) with a 60Amp main
breaker, and I'm there?

If you're feeding the sub via a breaker on the main panel, you don't
need to replace the main breaker in the subpanel.

Chris

Chris Friesen wrote:

I'm aware of ground loops. What does this have to do with an
insulated
ground bus in a subpanel?

Absolutely nothing.

(See my Mea Culpa on my response to Frank.)

It should have read "Insulated neutral bus".

The ground bus with the sub panel bonded to it's ground bus and then
carried back to service entrance will give single point grounding.

Lew

Frank Boettcher wrote:


If I want to have a 60 AMP subpanel, one method would be:

Buy a low cost package service entrance panel making sure what joins
the nuetral and ground buses is removable, remove the tie between the
nuetral and ground buses, make sure the ground bus is bonded to the
panel, replace the existing main breaker (which will probably be 100
amp or greater depending on the panel capacity) with a 60Amp main
breaker, and I'm there?


The (M)ain (L)ug (O)nly panel with an assortment of main c'bkr kits
was developed to provide the electrical distributor the maximum
flexibility of his inventory with the minimum investment.

For years, the standard was the 125A, MLO panel with various branch
arrangements.(Usually 60A and 100A)

As shipped from the manufacturer, they were ready to install as sub
panels, if if you added an insulated neutral, and used the existing
bus bar as a ground bus.

To convert to a service entrance panel, all you had to do was add a
main c'bkr kit since the neutral and ground connections shared the
same bus.

Today's higher electrical usage often dictates a 200A panel, which is
a whole new family of larger c'bkrs for main c'bkrs.

Lew

It's very common with metalworking machines. Coolant pumps and
DRO's operate on 117 v while the big motor operates on 220.
It seems silly to me to go to the trouble of wiring new circuits
without installing the third wire. It's a lot more trouble to add
later.

Doug Miller wrote:
In article , "Stephen M" wrote:

220 - 10/3...just in case you need it some day.

We've had that discussion here before. :-)

There's *no* reason to use 3-conductor cable for 240V power tools. It's just
unnecessary expense. Three-conductor cable is needed for combined 240/120
loads such as a range or a dryer, that have 240V heating elements and 120V
motors and/or control circuits. A power tool with a 240V motor needs only
two-conductor cable; there isn't even anything to attach the third conductor
to, if it's present.

Mike Berger wrote:

It's very common with metalworking machines.
snip

You must be new.

Trying to talk to Miller is like ****ing up wind.

After a while, you know better.

Lew

In article . net, Lew Hodgett wrote:
Mike Berger wrote:

It's very common with metalworking machines.
snip

You must be new.

Trying to talk to Miller is like ****ing up wind.

After a while, you know better.

****ed off because I pointed out your electrical errors *again*, I see...

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

In article , Mike Berger wrote:
It's very common with metalworking machines. Coolant pumps and
DRO's operate on 117 v while the big motor operates on 220.

Well, of course we were talking about woodworking machinery here... :-)

It seems silly to me to go to the trouble of wiring new circuits
without installing the third wire. It's a lot more trouble to add
later.

Which is why I said this, in the part that you snipped:

If you want to plan for "in case you need it some day" it's better to not
run cables at all, but instead pull individual conductors through conduit:
pull what you need now, now; pull what you need later, later.



Doug Miller wrote:
In article , "Stephen M"
wrote:

220 - 10/3...just in case you need it some day.

We've had that discussion here before. :-)

There's *no* reason to use 3-conductor cable for 240V power tools. It's just
unnecessary expense. Three-conductor cable is needed for combined 240/120
loads such as a range or a dryer, that have 240V heating elements and 120V
motors and/or control circuits. A power tool with a 240V motor needs only
two-conductor cable; there isn't even anything to attach the third conductor
to, if it's present.


--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.