Grounding/bonding (long)

Reply

  #1  
Old 10-15-05, 09:30 AM
ollie
Visiting Guest
Posts: n/a
Grounding/bonding (long)

Hi guys,
I retired from the trade in 1985, a project has come up and I'm trying to get up to date on the 2005 code. Especially the grounding and bonding issue. First is ... Has New York State adopted the 2005 code yet?
My son is adding an extension to his home in upstate New York. The plan is to have the foundation and shell contracted out and for us to do the finishing work. We will bring in a 300A service to the new extension. 200A will feed a panel for the extension and any new circuits. 100A will feed a 100A disconnect switch that will feed the old 100A panel. The old panel be converted to a sub-panel.
a- Sizing the Equipment Bonding Jumpers on the supply side of the service. I'm using Table 250.122 (for a 300A service). Is this correct?
b- Sizing the Grounding Electrode Conductor (GEC). I'm using Table 250.66 (for a 200A and 100A service). Is this correct.

I would like to use a Ufer ground for the Grounding Electrode. My son will be on site for the pour so getting the rod placed properly should not be a problem. Does the AHJ usually want to see the rod before the pour? Soares Bonding and Grouning (page 118, figure 7-6) shows two GEC's coming from two disconnets and landing on one Grounding Electrode. Soares says that this method is not directly addressed in the code but should be ok. Has anyone use this method? ...And ... Did it pass?
Thanks for the help
Ollie
 
Sponsored Links
  #2  
Old 10-15-05, 10:14 AM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
No, NYS has not yet adopted the 2005 NEC. In fact we never will for one and two family dwellings. We follow the NYS RSBC, where the electrical section is actually based on the 1999 NEC. I have heard we will go to the 2005 NEC in 2006 for commercial and for 1 & 2 family dwellings we will adopt the next RSBC which is I believe will during the year(?).

For a sole connection to a UFER you would use the permission in 250.66(B) which states the wire need NOT be larger than #4cu.

For a grounding electrode conductor you can use 250.66(A) which states the sole connection to a grounding electrode need NOT be larger than #6cu.

For your water bond you would use 250.104(A) which tells us to use 250.66 and is sized according to the largest service-entrance conductor.


BTW- Are you from LI or the City? That is the last time I heard the term "extension" used. I grew up on LI and that's what it was called.
We use the term "addition" up here.
Funny how the lingo differs.
 
  #3  
Old 10-15-05, 10:14 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,621
Ollie,

Could you please clarify an issue, Are you setting a 320 A socket feeding the 200 and 100 amp panel or disconnects?

The Ufer is normally 20 foot of rebar or bare copper in the footer, not a rod.
 
  #4  
Old 10-15-05, 10:18 AM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
Good point Boss about the rod. I glanced right over that one.

In fact, since we do not follow 2005 I would forget the UFER and just sink two rods and be done with it.
 
  #5  
Old 10-15-05, 12:40 PM
Member
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
the size of the Service-Conductors determines the size of the Grounding Electrode Conductor (GEC), Tbl. 250.66.

Presuming 350MCM copper Service-Conductors, the GEC would be #2 copper, and connects the Service Neutral to the Primary Grounding Electrode.

You must also install a Supplemental Grounding Electrode which can be connected by a #6 copper Grounding-Conductor.

Bonding----- Load-side of 200 amp C-B = #6 copper
Load-side of 100 amp C-B = 38 copper
(Tbl 250.122)
 
  #6  
Old 10-15-05, 12:55 PM
ollie
Visiting Guest
Posts: n/a
PCBoss
That's what were doing. When I said rod I ment rebar.

Speedy Petey
Yes originally from LI. After retireing I moved to PA and never look back.
As for using a Ufer. There was a rock in the drive way about 2 sq. ft and about 5 inches high a pain in the butt driving over. Drilled holes and put water in to see if we could break it up. No luck. Last summer got a guy with a back hoe to dig it out. The rock was the size of a VW. The place is full of such things. So the Ufer looked like to easest way to go. Where still in the early stages of planning.
Thanks
Ollie
 
  #7  
Old 10-15-05, 02:52 PM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
Originally Posted by PATTBAA
the size of the Service-Conductors determines the size of the Grounding Electrode Conductor (GEC), Tbl. 250.66.

Presuming 350MCM copper Service-Conductors, the GEC would be #2 copper, and connects the Service Neutral to the Primary Grounding Electrode.

You must also install a Supplemental Grounding Electrode which can be connected by a #6 copper Grounding-Conductor.

Bonding----- Load-side of 200 amp C-B = #6 copper
Load-side of 100 amp C-B = 38 copper
(Tbl 250.122)
Do you disregard 250.66(A)? I have installed many 400 amp services with just a #6 to one or two ground rods. This is absolutey code.
If you are tapping off this GEC for other electrodes then it must be sized to 250.66. If it is just to a rod then #6 is all that's required.

For a water bond it is #4cu for the average 200 amp service (4/0al or 2/0cu) , 250.104(A), using table 250.66
For "other" metal piping, 250.104(B), we use 250.122
 
  #8  
Old 10-15-05, 04:44 PM
ollie
Visiting Guest
Posts: n/a
Now you got me thinking. Here goes
Although this is a 300A service it's going to be split into a 200A and 100A.
Here's how I laid it out.
Table 310.15(B)(6) - 200A service needs 2/0 feeder wire ... 100A service needs #4 feeder wire.
I will double lug the meter and feed the 200A panel with 2/0 wire. and feed the 100A disconnect with #4 wire.
Table 250.66 says a panel feed with 2/0 or 3/0 wire needs a #4 copper wire for the GED. I will run a #4 wire from the grounded (neutral) buss in the 200A panel to the Ufer ground rod.
Table 250.66 says a panel feed with #2 or smaller needs a #8 copper wire for the GED. I will run a #8 wire from the grounded (neutral) buss in the 100A disconnect to the Ufer ground rod. Will there be a problem using two different size wires for the GED?

Getting back to my original question. What table do I use for the Equipment ground from the meter pan. That would be the bare or green wire that bonds the meter pan via a grounding bushing to the grounding system. I think it should be Table 250.122. A 300A circuit calls for #4 copper wire.
Thanks for the help, more to come
Ollie
 
  #9  
Old 10-16-05, 09:43 AM
Member
Join Date: May 2001
Location: Dry Side of Washington State
Posts: 738
Why don't you buy a meter/disconnect combo that has space for 2-240 volt circuit breakers? Then all the service grounding would be accomplished at the meter/disconnect. No main breakers would be required in the two sub panels. Pull 4-wires to each subpanel. The Equipment grounding conductor size for the sub panels is based on the size of the breaker feeding each one. In your case 100 and 200 amp breakers.
 
  #10  
Old 10-16-05, 11:38 AM
Member
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
Art 250.64, (D), Grounding Electrode Taps----------

"Where a Service consists of more than one enclosure, (2+ Dis-connect enclosures ), it shall be permitted to connect taps to the Common Grounding Electrode Conductor." ( which connects the Service Neutral to the "Primary" Grounding Electrode).

"The ( size of ) the common Grounding Electrode Conductor shall be based on the sum of the circular-mill area of the largest un-grounded Service Entrance Conductor" ( Tbl 250.66)

"The tap conductors shall be sized for the largest Un-Grounded Conductor ( connected) to the enclosure"

"The tap-conductors shall be connected ( so that) the common Grounding Electrode Conductor (remains intact) with out a splice or joint"
 
  #11  
Old 10-16-05, 12:05 PM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
I see your point. This is why I emphasized the fact that I was referring to a sole connection to an electrode.
If you are making taps, of course the sections you referred to are correct.

Typically, with two panels I will run an individual conductor from each to the ground rods if it is convienent.
 
  #12  
Old 10-16-05, 12:50 PM
ollie
Visiting Guest
Posts: n/a
Thanks to all for the replys. I was just checking if my interpretation of the code was ok. It appeares to be I just need to read a little further in the text. Were still in the early stages of plaining. The idea of the disconnect at the meter is one we were thinking about.
Ollie
 
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