Is there a 200 amp breaker box with 100 amp main

Users who are viewing this thread

Rayh78

Member
Messages
98
Reaction score
3
Points
8
Location
Colonial Heights, Virginia
Have a remodel to do and will sub out electrical.
Electrician I have used in the past said I cant do this.
Years ago I had the same situation. Small house with 100 amp service and customer does not want to pay for upgrade now but wants breakers. Instead of putting in just a 100 amp breaker box, I had a 200 amp Murray box put in and install a 100 amp main breaker instead of a 200 amp main. The box was still 200 amp to make a future upgrade easier. A murray 100 amp breaker fit in the same space as a 200 amp for the Murray brand. Which was not the same with square D. Since then if ever I contracted out any electrical we have used square D brand. But have this situation again and they dont make murray anymore. Is there another brand out there?
Electrician does not want to do this either. Use just a square D 200 amp box with a 100 amp square D line feed breaker because he saids maybe a problem with inspector.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
I'm by no means a pro, but it is my understanding that as long as the supply line capacity is not exceeded by the protection circuit, it is okay to use a smaller cb. Now, with more available slots, you are more likely to be able to trip the main breaker, but that's another issue. Logically, but maybe not by code, it should be in the same idea as using 12g wire on a 15A service, which could also use 14g. The wire size determines the maximum current that can be drawn.
 

Ian Gills

Senior Robin Hood Guy
Messages
2,743
Reaction score
3
Points
0
Location
USA
You need to convince the customer that they are mad.

When I tried to do the opposite (upgrade the service but not the panel) the extra cost of calling out an electrician just to do the panel in the future would have been much more than the modest increment I ended up paying to get it all done in one go.

Not to mention the requirement for another inspection.

Refuse.
 

Rayh78

Member
Messages
98
Reaction score
3
Points
8
Location
Colonial Heights, Virginia
Alittle more info.
This is a small 600 sq.ft. guest house on a seperate meter and has gas heat.
So it is questionable if an upgrade would ever be needed but they would like the option. And it would save some work. And the price difference between a 100 amp or 200 amp box is not that great.
Would save morethan that if ever an upgrade
 

Jim Port

Electrical Contractor
Messages
156
Reaction score
0
Points
0
Location
Maryland
Website
www.manta.com
I can see no logical reason to think about installing any more than a 100 amp panel for a 500 square foot house.
 

hj

Master Plumber
Messages
33,600
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
What is feeding this panel? If it is a subpanel, just install the 200 amp unit with a 100 amp breaker at the main panel. if it is being metered, the electric company can install new cables and meter, or just a 200 amp meter if their wires are adequate.
 

Ballvalve

General Engineering Contractor
Messages
3,581
Reaction score
45
Points
48
Location
northfork, california
600 sq feet with gas and 200 amps? Going to smelt aluminum?

60 amps is plenty like every three bedroom house had until 1970...

You can use a 100 amp panel and feed it with a 50 amp breaker, and I'll bet it NEVER trips.

200 amps is absurd unless they plan to add 4 more 600' units to this one.
 
Last edited:

Rayh78

Member
Messages
98
Reaction score
3
Points
8
Location
Colonial Heights, Virginia
Would use the same wire for now. Just so I understand options.
It would be against code to use 200 amp box. Blank off cover space for the factory main breaker and then use 100 amp line feed breaker.
thanks
 

hj

Master Plumber
Messages
33,600
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
You can use any panel you want, with or without the main breaker, as long as the breaker feeding it is appropriate for the wire to the panel. Although you might have a bit of difficulty attaching the wires to the buses without going through a main breaker.
 

TWEAK

New Member
Messages
86
Reaction score
0
Points
0
Location
Bay Area CA
Does the guest house have its own independant service entrance? Or is it a sub panel fed off the main house panel?
 
Last edited:

Bob NH

In the Trades
Messages
3,310
Reaction score
9
Points
0
Location
New Hampshire
You could buy a separate 100 amp main for the new panel but it would cost almost as much as the panel.

If you go to HDepot you can buy a 200 Amp Homeline panel with a number of breakers. Additional breakers are as cheap as any you can get.

Run some appropriate size wire for 100 Amps (2 hots, neutral, and ground) from the existing 100 Amp panel to the new panel, connecting to the lugs of the 100 Amp panel AFTER the main breaker. Connect to the standard input of the new panel. If there are no lugs you can probably buy a cheap 100 amp branch circuit breaker for the old panel on the famous auction site.

The new Homeline panel will have separate terminal strips for neutral and grounds, which you must use. The neutral should not be grounded at the new panel. Leave out the big green screw that they will furnish.

You can leave existing circuits in the old box or move them to the new panel. You can use the old panel as a splice box if necessary.

If there is adequate space you can connect the two panels through a short conduit, or multiple conduits. For the 15, 20, and 30 amp circuits with THHN wire you can run as many as 9 current carrying conductors in a single conduit. You can run more if it is a very short run.

If you ever upgrade to 200 Amps (such as if you need it for "grow lights" for yourpot plants) you can eliminate the 100 amp panel and connect the new service to the 200 amp panel. If you are going to do it to code you will need to provide grounding adequate for the 200 Amp service.
 

cswilson

New Member
Messages
2
Reaction score
0
Points
0
Location
North Bay, ontario, canada
I don't know about it where you are. But I just recently replaced my main panel as well as the separate service I had for my garage. I bought 2 new panels. one is a 100 A the other a 200A on looking up the specs of the panels. the 100a is rated higher then they are breakered for.

. the 100A is rated as a 200, but came with a 100a breaker (both panels are identical except for this)
 

TWEAK

New Member
Messages
86
Reaction score
0
Points
0
Location
Bay Area CA
has own seperate service entrance.

That being the case....

In San Jose CA, where I live, you can't do that. PG&E, the poco here, won't let you install a 200A box with 100A main breaker. I know this for a fact because I tried. I wanted to replace an old 100A Zinsco panel that was scaring me - I had a couple of instances where breakers didn't trip and branch wiring became the fuse. Zinsco is nearly as bad as Federal Pacific. Anyway, I wasn't ready to spend the bucks to upgrade the underground service quite yet. So I wanted to put in a 200A box fitted with 100A main breaker, and upgrade to 200A later. PG&E, would not approve it. I had to either put in another 100A panelboard or if I wanted a 200A panel I had to upgrade the underground service. Ended up upgrading.
 

Jetlag

New Member
Messages
84
Reaction score
0
Points
0
Location
Ga.
This might be hard to believe but the code allows you to install 2 -100 amp panels on the same service entrance , even though the meter , service entrance cable and every thing else is only 100 amp . All you have to do is show that the calculated load for install is less that 100 amp . The NEC code that allows this is NEC 230.90 A exception 3 . There is a debate going on right now at www.mikeholt.com , look under forums, NEC, post entitled, "hypothetical-table" . My user name is jetlag and I am argueing agaist this kind of install being allowed .
 
Last edited:
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks