100 Amp Service

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  #1  
Old 07-26-01, 12:41 PM
Guest
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I own a bungalow with 100 amp service and a full 14 breaker box. I need to add room for two 220 window A/C's and was wondering if a subpanel would be the way to go. I was also told that there are 30 breaker panels out there for 100 amp service. Any input will be appreciated.
 
  #2  
Old 07-27-01, 03:52 AM
Wgoodrich
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First look on the inside of your panel door. You should find a label showing the circuits in that panel. Look to see if the circuits say 1 A / 1 B then 2 A / 2 B etc.

If you have this type marking on that label you panel is designed for 1/2 size breakers. You could then replace two of those existing full size breaker and buy two 1/2 size 120 volt breakers making room for your new 220 volt circuits. The buy a 240 volt 1/2 size breaker that will serve two 240 volt circuits. Should solve your problem.

Most 100 amp panels are capable of carrying 20 circuits, some don't but I am hoping that yours does by expecting 1/2 size breakers to be installed.

Let us know what you find.

Wg
 
  #3  
Old 07-27-01, 08:41 AM
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100 amp service

Thanks for the info. I'll check when I get home tonight and let you know. Isn't there a limitation on the number of 1/2 size breakers? Siemens makes a 100 AMP 30 Space 30 Circuit Indoor Main Breaker Load Center Model: #G3030MB1100CU. 100 AMP 30 Space 30 Circuit Indoor Main Breaker Load Center with the following specs. Would this also be an alternative?

Model G3030MB1100CU

UL listed for use with 60 or 75 degrees C wire
UL listed for series ratings up to 100,000 AIC
Interior - removable for quick wire pulling
Knockouts - ideally sized and located for easy wire entry and exit
Class CTL - conforms to requirements for circuit limiting
Enclosure, cover, interior and main are shipped complete in one carton
Have factory installed 22-KA IR main breaker and copper bus bar
Equipped with insulated and bonded split neutrals for faster and neater wiring

Amperage: 100 amps

Number Of Spaces: 30

 
  #4  
Old 07-27-01, 04:57 PM
Wgoodrich
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42 circuits is the limit in a lighting or appliance panel board no matter what the amp rating is. There used to be a limit of 20 circuits in a 100 amp panel but that no longer applies. 42 circuits is now the limit in one panel regardless of the amp rating.

As for the panel you discribed compared to the panel you have I can't answer that question. We don't yet know the panel you now have. You may be buying a 30 circuit panel to replace a panel that may have 28 circuits using 1/2 size breakers. A two circuit gain just doesn't sound like a smooth move. Check what your existing panel really is before you jump into anything

Wg
 
  #5  
Old 07-27-01, 05:35 PM
Guest
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100 Amp Service

Thanks for the feedback! Checked the panel and found it is a GE 16 breaker Loadcenter with options for 1/2 size breakers, 20 poles max rating. There are already 4 1/2 breakers in use, bringing my total to 18. Doesn't seem very useful to pull the two remaining breakers to split into 1/2 size and fill up to 20 unless I can split more per your prior reply. I'm a little iffy about the panel rating versus your comments.
 
  #6  
Old 07-27-01, 06:13 PM
Wgoodrich
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I suspect if this panel were my panel and I intended to upgrade my 100 amp 20 circuit main service rated panel to a new panel, I doubt that I would spend the money just to add 10 circuits. Have you ever calculated a demand load calculation to discover the minimum service size required for you home? Have you ever checked to see if each of these existing circuits really need to be separated circuits? Is it possible to combine some unused branch circuits to make space in your existing panel? Have you thought about pricing what it would take to upgrade to a 200 amp 42 circuit panel compared to replacing the existing 100 amp panel that has a max circuits of 20 with the same 100 amp panel that has a max circuit of 30 amps. Maybe if you are going to upgrade it might be money ahead spending the extra money and upgrade to the 200 amp service. You might want to sit down and think about down the road for future. Is it likely you will be facing this same delemma in the near future again?

Just some questions to get you thinking for the future.

Don't you love your question answered with a bunch of more questions?

Wg
 
  #7  
Old 07-28-01, 07:59 AM
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100 Amp Service

You do ask a lot of questions, but they are all good ones. I did a minimum load calculation last night after I replied and found that even with the two new A/C units that aren't installed yet, my load is about 65 amps. Not alot of electrical draw - no electric baseboards or other big drains. The house was pretty well split up circuit wise when we remodeled about 12 years ago. Kitchen circuits, dishwasher, garage, laundry, ceiling lights, etc.. I don't think the 200 amp upgrade would make sense for us, but if I can put 30 circuits on the existing 100 amp service with a new panel, this may be my best option. I'll still have a few circuits to play with.
 
  #8  
Old 07-28-01, 10:09 AM
Wgoodrich
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Sounds like you made an informed decision. Now a word of caution do not try to change that panel for panel while the feeders are still hot. That action makes me nervous when I see a pro do that. Those hot feeders are unfused and very unforgiving. Check and confirm that you are allowed to perform this procedure with your local electrical inspector and what permits and inspection proceedures that are required, contact the power company and set a day that they can pull your meter to de-energize you main feeders. Then change your panels and have the meter reset. That way I know you will be unhurt and can come back to us for more electrical projects.

Hope we were of some help to you.

Wg
 
  #9  
Old 07-28-01, 11:06 AM
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100 Amp Service

Thanks. You were more help than I imagined and I'll be sure to come back whenever I need a little assistance.
 
  #10  
Old 07-30-01, 10:52 AM
J
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Join Date: Sep 2000
Location: Fayetteville, NY, USA
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Swapping a 100 amp panel with another 100 amp panel is not a huge job. If you are fairly confident in your electrical ability you might want to call your local code enforcement office and find out if homeowners are allowed to do their own electrical work. they will require a permit and inspection. Absolutely listen to Wg about NOT doing this live. Your utility company will cut you off for the time needed to switch panels but they will not cut you back on unless they see a certificate of compliance from your electrical inspector.

Here's one job where it may be a good time to call an electrician. It is not an expensive job and an experienced pro could knock it out in a couple hours. The electrician would handle all the coordination with permits/inspection/utility, etc., and would schedule things such as getting the utility over there for the cut-off and getting them back for the cut-on, and making sure the inspector gets there first. I would expect this job to cost approximately $300 - $400.

Hope that helps.
 
  #11  
Old 07-30-01, 11:22 AM
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100 amp service

Thanks Juicehead! I'm already looking into local pro's to do this. Too soon we get old, too old we get smart.
 
 

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