Wiring a new shop

Page 2 of 3  
Chris Friesen wrote:
> Now I'm no pro, but it seems like some of these suggestions are overkill.
One word: Standardization.
You buy wire in full spools instead of cut lengths.
You buy devices in quantity.
You provide for future expansion.
Overall, you save money.
Lew
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 16 Jul 2007 23:12:43 GMT, Lew Hodgett

Easily obtained? None of the low cost "packaged panels" I've seen have a 60 main. 60 main will be a different configuration than the 60 branch? Electrical supply house?
Insulated ground bar means remove the strap to the nuetral if so configured? But ground buss needs to remain bonded to the panel, correct?
Thanks,
Frank

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Frank Boettcher wrote:
> Easily obtained? None of the low cost "packaged panels" I've seen > have a 60 main. 60 main will be a different configuration than the 60 > branch? Electrical supply house?
The 60A bkr is the same, but has different hardware to be used as a main bkr.
Any decent electrical distributer can help you.
> Insulated ground bar means remove the strap to the nuetral if so > configured?
NO, what you are describing is a bonding strap used to bond the neutral to the enclosure when the panel is used as a service entrance panel.
An insulated ground bus is exactly that.
It will look like the neutral bus but be insulated from the panel.
An electrical distributer will have them as a kit.
>But ground buss needs to remain bonded to the panel, > correct?
NO, not at the sub panel, but yes at the main service entrance panel.
You need to have a heart to heart with the local building department.
Local codes vary.
Some places will want a ground rod at the sub panel, some may not and want the earth ground carried all the way back to the service entrance panel.
If you try to out guess the inspector, you lose, every time out of the box<G>.
Lew
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Lew Hodgett wrote:

At least in my circumstance the subpanel did not use an insulated ground. The bonding screw was removed from the neutral bus (so that neutral was separate from ground), but the ground bus is bonded to the panel (and is tied to the main panel ground via a bare conductor).
The inspector signed off on it no problem.
What's the point of an insulated ground?
Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.
The cathodic electrode industry exists to minimize the effects of "Ground loops" or stray electrical currents in the soil.
Lew
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Lew Hodgett wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Absolutely nothing. He may be confusing "insulated ground" with "isolated ground" or perhaps with "insulated neutral."
In any event, it is a Code violation to insulate the grounding bus from the panel chassis in either a main panel or a subpanel: metal enclosures are *required* to be grounded.

And that is as it should be. This talk of insulating the grounding bus from the panel is nonsense.
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Chris Friesen wrote:

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_grounding_vs_bonding_5/index.html
--
Jack Novak
Buffalo, NY - USA
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

*What* "resulting ground loop"?
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes, at the subpanel, as well as at the main panel. He's asking about the ground bus. Not the neutral bus.
Correct is: Ground bus *must* be bonded to panel chassis in main *and* subpanels. Neutral bus *must* be bonded to ground in main panel. Neutral bus *must*not* be bonded to ground in a subpanel.
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 17 Jul 2007 16:14:22 GMT, Lew Hodgett

No, I'm describing a tie bar that ties the nuetral and ground buses together which is normal in a service entrance panel but not for a subpanel.

Goes against everything I've read. In many main panels the nuetral and ground buss are tied together with a strap or tie bar, which insures that both buses are grounded. Removing that strap in a panel makes it suitable to use as a subpanel. Both the insulated ground and the nuetral in the sub continue to be grounded through their paths back to the main.

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.
Frank
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Gentlemen, you're *both* right here. In main panels, as you're both aware, the neutral bus is bonded to ground. The method of doing so varies depending on manufacturer. I've seen four different types of jumpers: - bonding strap connecting the neutral bus to the panel chassis - bonding strap connecting the neutral and ground buses - bonding *screw* through the neutral bus into the panel chassis - solid copper wire connecting the two buses Regardless of the method, the jumper must be removed if the panel is used as a subpanel.

You've got that backwards -- it's the *neutral* bus that's insulated from the panel, *not* the ground bus.
Ground bars *must* be bonded to the panel.

Exactly right.

Wrong. Ground bus *must* be bonded to the panel, without regard to whether it's a main or sub.

Exactly right.
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 17 Jul 2007 20:10:02 GMT, snipped-for-privacy@milmac.com (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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.

Bingo!
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Frank Boettcher wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He's confused. The subpanel needs an insulated *neutral* bus. The ground bus *must* be bonded to the panel chassis. And the bonding strap between the neutral and ground buses must be removed.
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bob AZ wrote:

What capacity AC unit did you get? Did you installl it yourself? What brand is it?
Thanks!
--Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.