sub panel 3 wire detached building

Reply

  #1  
Old 11-18-11, 10:28 AM
Member
Thread Starter
Join Date: Nov 2011
Location: usa
Posts: 7
Question sub panel 3 wire detached building

Sub Panel Grounding 3 Wire
I am running a sub panel to a detached garage 100 feet from the main 200 amp house panel.
Using 3 AWG 600 volt THW copper – 3 conductors run in underground pvc conduit to sub panel
Have installed 2 – 10’ grounding rods 6 feet apart connected via #6 ground wire up to panel
Sub Panel is 100 amp with main top disconnect breaker – using a 60 amp breaker at the house main panel for the sub feed line.
Q1. What is proper grounding/bonding procedure for this setup?
Q2. I also have run in separate conduit low voltage wires 75 ohm coax – 8 cond CAT5 cable and 4 cond 18 gauge communication cable – any issues running these?
Thanks kdayton
 
Sponsored Links
  #2  
Old 11-18-11, 11:37 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
Originally Posted by kdayton View Post
Q1. What is proper grounding/bonding procedure for this setup?
You need to pull a #8 green or bare ground wire through the conduit, buy an add-on ground bar kit for the subpanel, and electrically isolate the neutral bar be removing the bonding screw or strap. The ground rods connect to the ground bar, not the neutral bar. When installing branch circuits in the subpanel, make sure to get the ground and neutral wires on the correct bars.

There's nothing wrong with using the 60A breaker, but you can bump it up to 100A if you want; or decrease the conductors to #6 copper if you only need 60A.

Q2. I also have run in separate conduit low voltage wires 75 ohm coax – 8 cond CAT5 cable and 4 cond 18 gauge communication cable – any issues running these?
Not once the ground wire is installed.
 
  #3  
Old 11-18-11, 02:13 PM
Member
Thread Starter
Join Date: Nov 2011
Location: usa
Posts: 7
the ground wire - the 4th wire

Thanks Ben - very helpfull - When I had the trench open I ran a 2nd pvc conduit, can I use this to fish the ground wire in or does it have to be in the same conduit as the other feed lines? Obviously it would be easier to use the empty conduit?

Thanks Keith
 
  #4  
Old 11-18-11, 02:30 PM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
It has to run in the same conduit with the hots and neutral. The conduit should be 1" trade size or larger to accommodate these size wires.
 
  #5  
Old 11-18-11, 02:44 PM
Member
Thread Starter
Join Date: Nov 2011
Location: usa
Posts: 7
The conduit I ran was 2" for the 3AWG so the snake and #8 should go fairly easy but I have a lot of respect for Mr Murphy - Thanks Again!!
Keith
 
  #6  
Old 11-18-11, 02:52 PM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
Shouldn't be a problem in 2" pipe. Hope all goes well.
 
  #7  
Old 11-18-11, 05:57 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,213
Using 3 AWG 600 volt THW copper
Just curious, where did you find THW wire? I haven't seen any new THW in years!
 
  #8  
Old 11-18-11, 08:56 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,984
Originally Posted by CasualJoe View Post
Just curious, where did you find THW wire? I haven't seen any new THW in years!
I was wondering the same thing!
 
  #9  
Old 12-27-11, 11:34 PM
Member
Thread Starter
Join Date: Nov 2011
Location: usa
Posts: 7
Question the thw 3

i had the wire for years - knew i was going to do this someday and that day came. making a wood shop to flex some creativity are there any issues by using it?

got the #8 in the same conduit and will be doing the tie in this week


thanks
keith
 
  #10  
Old 12-28-11, 04:41 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,213
i had the wire for years - knew i was going to do this someday and that day came. making a wood shop to flex some creativity are there any issues by using it?
No issues that I am aware of. THHN might be slightly easier to pull, but THW conductors in 3" conduit should be a breeze.
 
  #11  
Old 12-31-11, 11:34 AM
Member
Thread Starter
Join Date: Nov 2011
Location: usa
Posts: 7
Question sub on sub and conduit

Thank You CasualJoe! I would like to add a sub panel to the sub panel - why - so I can turn off via main breaker in 2nd panel, all machinery and shop outlets used for tools so my grandchildren don't turn something on when I am out of the shop. So the main panel is for heat and lights and ext outlets etc.

Q1 - The question is for this panel do I assume the grounding/bonding same as the sub panel which is feeding this 2nd one? - isolated neutral with bonded ground bar.

FYI - from the first post, I did change the 60 amp to 100 amp in the house service entrance panel. This second sub panel will be a 60 amp.

Q2 - can i use pvc conduit to run thhn for all equipment or must it be emt?

FYI - all equipment is 240 - table saw, planer, drum sander, jointer, drill press, combo sander, dust collector and air purifier.

Q3 - do i need to run gfic breaker on all outlets or just outside outlets?

DIY - i live in MA
 
  #12  
Old 12-31-11, 11:40 AM
Member
Thread Starter
Join Date: Nov 2011
Location: usa
Posts: 7
Q3

the outlets in q3 are 120 the circuits
 
  #13  
Old 12-31-11, 12:13 PM
SeaOn's Avatar
Member
Join Date: Dec 2011
Location: USA
Posts: 351
No issues that I am aware of. THHN might be slightly easier to pull, but THW conductors in 3" conduit should be a breeze
THHN is not rated for this application (or installation).


Q1 - The question is for this panel do I assume the grounding/bonding same as the sub panel which is feeding this 2nd one? - isolated neutral with bonded ground bar.

FYI - from the first post, I did change the 60 amp to 100 amp in the house service entrance panel. This second sub panel will be a 60 amp.
Yes!

Q2 - can i use pvc conduit to run thhn for all equipment or must it be emt?
I don’t see an issue with it. But who am I

FYI - all equipment is 240 - table saw, planer, drum sander, jointer, drill press, combo sander, dust collector and air purifier.
Are you planning to run a shop—where more than one of the above will be on at the same time. If so, make sure you have done the proper demand load calculation for your service.

Q3 - do i need to run gfic breaker on all outlets or just outside outlets?
Not for the 240v devices. You will need one for 125v receptacles that are located in a garage with a floor level at or below grade—which is not intended for habitable rooms, and limited to storage areas, work areas, and similar areas. Yes, the outdoor 125v outlets will need GFCI protection.
 
  #14  
Old 12-31-11, 12:42 PM
Member
Thread Starter
Join Date: Nov 2011
Location: usa
Posts: 7
Question summary

Thank You SeaOn!.

The feed cable is 170 feet (3) - THW 3AWG with #8 green ground in a 2" PVC conduit (not 3").

So I will do ALL 120 volt outlet circuits with GFIC breakers.

When I poured the floor - I ran conduit (1.5 inch) to each wall to reduce wall conduit runs.

Q -Is it true that if the lighting is hard wired, they do not require a GFIC or would you suggest it for safety?
 
  #15  
Old 12-31-11, 12:52 PM
SeaOn's Avatar
Member
Join Date: Dec 2011
Location: USA
Posts: 351
In your case, lighting does not need GFCI protection (Side note: Lighting will be protected if not hardwired—seeing that they will be plugged into a protected receptacle). Only the 125v receptacles will need protection—if they fall under the rule I posted in my last.
 
  #16  
Old 12-31-11, 02:20 PM
Justin Smith's Avatar
Member
Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
Although not required, I'd GFI the lights.
 
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
'