Knockout on a pre-stamped KO on Panel

Reply

  #1  
Old 03-25-14, 03:41 PM
Member
Thread Starter
Join Date: Jul 2009
Location: NYC
Posts: 302
Knockout on a pre-stamped KO on Panel

I'm leaning on making a 1" KO in a area of the panel where it has a 2" or so pre stamped KO.

Is this OK to do ?

There is not other area I can see that will accomodate the 1" conduit I plan to run to the panel
 
Sponsored Links
  #2  
Old 03-25-14, 03:51 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
How do you plan on punching this hole? A drill will cause the existing KO to come loose. About the only safe way to do it is with a punch set. You can do that anywhere on the box, basically, not just on the KO's.
 
  #3  
Old 03-25-14, 03:59 PM
Member
Join Date: Mar 2014
Location: US
Posts: 7
You can, but I'm pretty sure the code requires using a grounding bushing on the connector in the panel. Pre stamped holes aren't considered to have continuity for grounding.
 
  #4  
Old 03-25-14, 04:04 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Dreamland, what about the stepped KO's on a box?? They have at least 3 connections offset to the box. Just curious.
 
  #5  
Old 03-25-14, 04:05 PM
Member
Thread Starter
Join Date: Jul 2009
Location: NYC
Posts: 302
Punch Set.
The area is the only area where I can make the 1" KO.
 
  #6  
Old 03-25-14, 04:11 PM
Member
Join Date: Mar 2014
Location: US
Posts: 7
I was just looking in my code book, but it's 2008 and I don't see it mentioned. I think the 2011 changed for using concentric and eccentric KOs. I've had to use bushings on jobs, but I don't remember what kind of KO's they were. Either one or the other, or all types of KOs need grounding bushings now.
 
  #7  
Old 03-25-14, 04:40 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,516
Usually only the incoming service requires a bonding bushing. Technically it's required on a concentric knock out only but I use them on all incoming piped service connections.

If you press too hard you may end up knocking out that 2" or so KO and then you could use donuts(reducing washers) to fill the hole.

Name:  donut.jpg
Views: 826
Size:  21.7 KB
 
  #8  
Old 03-25-14, 04:51 PM
Member
Join Date: Mar 2014
Location: US
Posts: 7
The reducing washer is a good idea. You may be right about the feed being whats actually required for the bushing. Some of or jobs are specced to put bushings on all the pipes using KOs coming into a panel. That might be what I'm thinking about.
 
  #9  
Old 03-25-14, 04:54 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,516
Usually connectors like romex, MC or BX connectors are too short to put bushings on but any pipe run coming into the panel should have a bushing on it. Just a plastic bushing.... not a bonding bushing.
 
  #10  
Old 03-25-14, 04:57 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,365
I don't remember seeing any changes regarding eccentric or concentric knockouts.
 
  #11  
Old 03-25-14, 05:46 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,221
I was just looking in my code book, but it's 2008 and I don't see it mentioned. I think the 2011 changed for using concentric and eccentric KOs. I've had to use bushings on jobs, but I don't remember what kind of KO's they were. Either one or the other, or all types of KOs need grounding bushings now.
In my area, when using metal conduit on a service, a concentric knockout requires a bonding bushing, but with an eccentric knockout you would use a grounding locknut with a plastic insulating bushing. Personally, I see nothing wrong with using a bonding bushing rather than the grounding locknut, but the labor and material is a little higher.
 
  #12  
Old 03-25-14, 06:11 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,365
The code requires the bushing when the coonector does not provide a smooth edge or when conductors #4 and larger are used.
 
  #13  
Old 03-25-14, 08:27 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
The area is the only area where I can make the 1" KO.
If you're removing a 1-3/8" KO (for 1" ID conduit) and leaving any concentric or eccentric KO rings in place, you must use a bond bushing.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'