Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 11-28-2011, 09:39 PM   #1
"So I Re-Wired It"
 
MisterZ's Avatar
 
Join Date: Nov 2011
Location: NorthEast USA
Posts: 258
Share |
Default

[Q]100amp Main 100amp Sub


Hello all, forgive me if this has been answered. searched around but did not find an "absolute" answer

i currently have 100 amp service w/ 100 amp main breaker panel. i have a 100 amp sub panel which is installed indoors about 20' from the main.
used 2-2-2-4 wire, isolated neutral and ground, etc. the subpanel is wired properly

my main question is, can i use a 100 amp breaker in the main panel to supply the sub??
i have read several post which say you can, and several posts which say you must use at most 60 amp double pole breaker.

please be so kind and tell me the maximum size breaker i can use in the sub panel. TIA

BTW, they are both Homeline Suare D panels, and im not adding extra equipment, just separating the existing wiring for upstairs/downstairs

MisterZ is offline   Reply With Quote
Old 11-28-2011, 09:46 PM   #2
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,360
Default

[Q]100amp Main 100amp Sub


If that 2-2-2-4 cable is aluminum, then the largest breaker you can feed it with is a 90 Amp.

You do not have to change the main breaker in the sub-panel when you feed it with a smaller breaker from the main panel.

__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is online now   Reply With Quote
The Following User Says Thank You to kbsparky For This Useful Post:
MisterZ (11-28-2011)
Old 11-28-2011, 09:50 PM   #3
"So I Re-Wired It"
 
MisterZ's Avatar
 
Join Date: Nov 2011
Location: NorthEast USA
Posts: 258
Default

[Q]100amp Main 100amp Sub


thank you for the quick response. yes the cable is aluminum.
ok, so i can get a 90amp breaker then. so you are saying this wire is not rated for 100amp?? or no matter what im only allowed 90??
MisterZ is offline   Reply With Quote
Old 11-28-2011, 09:56 PM   #4
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,360
Default

[Q]100amp Main 100amp Sub


Correct. 90 Amp max. Table 310.16 of the NEC, [2011 edition table 310.105(B)(16)] type XHHW insulation, 75 degree termination.

There is an exception in the Code that allows a #2 aluminum cable to be protected at 100 Amp IF it supplies the entire dwelling. Since that is not the case when installing a sub-panel, that exception does not apply here.
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is online now   Reply With Quote
The Following 2 Users Say Thank You to kbsparky For This Useful Post:
HouseHelper (11-29-2011), MisterZ (11-28-2011)
Old 11-28-2011, 10:14 PM   #5
"So I Re-Wired It"
 
MisterZ's Avatar
 
Join Date: Nov 2011
Location: NorthEast USA
Posts: 258
Default

[Q]100amp Main 100amp Sub


Excellent!! that is the info i was looking for

thank you kbsparky. this forum is great, i look forward to helping out whenever possible
MisterZ is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Heat for a basement with Pellt Stove on Main Floor magnum44 HVAC 1 11-20-2011 08:55 AM
Main Circuit Breaker Question vladmir1111 Electrical 2 08-20-2011 08:15 PM
main lug or main breaker kenmore Electrical 14 06-18-2011 11:13 AM
Replace main panel? And lots of other ?s Bcoleman6 Electrical 13 01-22-2008 09:40 AM
main lug vs main breaker for sub panel diyll Electrical 1 01-17-2008 08:18 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.