100 amp sub-panel

Reply

  #1  
Old 01-21-16, 01:26 PM
Member
Thread Starter
Join Date: Jul 2015
Posts: 29
Received 0 Votes on 0 Posts
100 amp sub-panel

Hello all - this is probably a very basic question but it's something I'm curious about. We had a 100-amp sub-panel put it as we're in the process of finishing our basement and needed more circuits. The sub-panel has room for about 15-20 additional circuits. My question is, what does the "100-amp" refer to? Does that mean I can only have 5 20-amp circuits or 6 15-amp circuits in the box? Or does that just mean the most it can handle is 100-amps all at one time (that would be a lot, right)? Thanks!
 
Sponsored Links
  #2  
Old 01-21-16, 01:58 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,996
Received 39 Votes on 34 Posts
If fed by a 100 amp breaker you could run up to 100 amps at 240 volts or 200 amps at 120 volts. Many houses run on less than 100 amps.
 
  #3  
Old 01-21-16, 01:58 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,996
Received 39 Votes on 34 Posts
Adding the breaker handles is meaningless .
 
  #4  
Old 01-21-16, 02:11 PM
Member
Thread Starter
Join Date: Jul 2015
Posts: 29
Received 0 Votes on 0 Posts
Thanks. What are breaker handles? Are those the individual circuit breakers?
 
  #5  
Old 01-21-16, 03:00 PM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 42 Votes on 40 Posts
The amp ratings printed or stamped on the handles of the breakers (e.g. 15, 20, 30). In other words, a 100A breaker panel can support many more than 5 20A breakers due to the fact that branch circuits do not operate at 100% capacity for extended periods of time. The electrical code provides a formula called a "demand load calculation" to figure out what the realistic capacity of a panel is.
 
  #6  
Old 01-21-16, 03:22 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
And of course the breaker supplying the panel can be less than 100 amps. It isn't uncommon to use a 100 amp panel on a 60 amp breaker just so you have enough space for all the breakers. All the 100 amp designation means is that is the maximum amperage it is rated for.
 
  #7  
Old 01-21-16, 07:59 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,271
Received 43 Votes on 35 Posts
All the 100 amp designation means is that is the maximum amperage it is rated for.


we're in the process of finishing our basement and needed more circuits.
In all probabilty you'll never add more than 20 to 30 amps maximum in a typical basement finish. Like you already said, you just needed more circuits.
 
  #8  
Old 01-21-16, 08:07 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,493
Received 33 Votes on 25 Posts
I have a 200 ampere service. Between the service panel and two sub-panels I have at least 900 amperes worth of circuit breakers. I doubt that I have ever pulled as much as 100 amperes through the main CB.
 
  #9  
Old 01-22-16, 04:33 AM
Member
Thread Starter
Join Date: Jul 2015
Posts: 29
Received 0 Votes on 0 Posts
Thank you all for your help - I appreciate it!
 
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
 
Ask a Question
Question Title:
Description:
Your question will be posted in: