Building a garage with a full home panel

[S. BROWER]

I am going to build a detached garage and the house 200 amp panel is full. I need to add a 100 branch circuit to the new garage 75' and need to know what to add to allow this new circuit. I assume a buss bar/box to allow for feed from the house side of the meter. I have read the NEC codes and have not found specifice for this circumstance. I will contact my electric supplier but want to have a better idea of what is required. Any help and or comments will be appreciated.

The building construction is the easy part - just want to make sure I don't get in trouble with the insepctors for the electrical.

S. Brower

 

[LoneGunman]

Odds are you will not be able to do anything in the meter enclosure, in most areas that's the power company's domain. Depending on your panel you may be able to replace the existing lugs with double lugs and feed the garage from them, the problem with that is I believe you'll have to run wire that will handle 200 amps as that's what your panel is rated for.

Have you thought about adding some tandem breakers so you can free up two spaces in your panel?

 

[IDASHO]

How big is your house??

I can understand having a ton of circuits, but I dont think Ive ever seen a run-of-the-mill home max out a 200Amp box.



If you just have a ton of circuits, consider making space by installing "double single pole" 15AMP or 20AMP breakers like these:

 

[LoneGunman]

Idasho brings up a good point, unless it was a monsterous house I don't think I've seen more than 80-90 amps on a residential service. You could turn everything on that you can think of, take a clamp on ammeter and write down how many amps are on what breakers. You may be able to combine a few circuits to get your required spaces. Be aware by code you have to have a minimum of two circuits for your kitchen receptacles.

 

[S. BROWER]

The house is 3200 sq.ft., cutler hammer 200 amp panel with 17 20 amp, 10-15 amp, 4-30 amp, 1-60 amp, 1-25 amp, 1 vaccant slot. The builder ran a lot of small circuts for which I believe I can combine some. The double single pole breakers sounds like the best alternative.

I replaced the electric cooktop with gas when bought the house, freeing up a 30 amp breaker. I have connected a welder to this circut which will move to the new shop.
Is there a 100 amp breaker for this panel?

I believe my problem is solved as a result of this site.

Thanks.

 

[dwilliams35]

Sure there's a 100 A breaker for them.. I'd just put a 100A subpanel right next to the main one: it'll allow you to move some of those circuits if needed, won't have to combine anything, won't have to get the power company involved, and will leave you some room for additional circuits.

 

[rinny_tin_tin]

I am going to build a detached garage and the house 200 amp panel is full. I need to add a 100 branch circuit to the new garage 75' and need to know what to add to allow this new circuit. I assume a buss bar/box to allow for feed from the house side of the meter. I have read the NEC codes and have not found specifice for this circumstance. I will contact my electric supplier but want to have a better idea of what is required. Any help and or comments will be appreciated.

The building construction is the easy part - just want to make sure I don't get in trouble with the insepctors for the electrical.

S. Brower

Do an electric plant load analysis (EPLA) using a spread sheet to showing that the possible combination of existing loads plus garage loads would never exceed 200A; then,

****** another 200 A panel right next to your existing panel using the same size feeder conductors going to the existing main panel;

Install a 100 A breaker to the new panel and feed the garage

 

[S. BROWER]

Not sure I understand adding a subpanel next to the existing. I need the 100amp service to route to the new shop 75' away. I need to free up space in the exisitng panel to provide the 100 circut.

By the way, found a website for Pacific Coast breakers. They sell new and reconditioned breakers. The reconditioned are 1/2 price of new. Any history with reconditioned breakers? Like to save money, however, don't to comprimise the new power feed.

 

[tundradude]

I have a 200 amp panel in the house. In that panel there is a 100 amp breaker feeding my 100 amp panel in the garage. The key here is you're allowed to exceed that amperage by 70%. (Because you never expect to have everything on at one time) Your local code may vary, but its probably similar.

The kicker is ... that 100 amp breaker takes up 8 slots in the panel. (It looks like it only takes 4, however it is oversized so you cannot place another breaker beside it)

 

[rinny_tin_tin]

Sorry, I re-read Rinny-Tin-Tin reply and understand the response.
Qustion - ****** from the Main panel to the secondary -
What is the procedure for ******. Connect to the service to the 200 breaker?

Does this require a double lug connector?

Exactly - basically, replace the single lug with a double and to the double- add the conductors to your nippled panel.

Nippled in your case would mean that the panels are right next to one another - or close, and there is a pipe generally on the side of the panels that goes from one panel to the other, and you run your conductors from the main panel to your second panel through the pipe. You probably have seen it before.

 

[rinny_tin_tin]

Exactly - basically, replace the single lug with a double and to the double- add the conductors to your nippled panel.

Nippled in your case would mean that the panels are right next to one another - or close, and there is a pipe generally on the side of the panels that goes from one panel to the other, and you run your conductors from the main panel to your second panel through the pipe. You probably have seen it before.

...or as DWilliams wrote - simply put a 100 A panel right next to your 200 (you can ****** these too) and move some of your ckts from the 200A to the 100 A --and feed the 100 A panel with a 100 A CB (space freed up from the moving of ckts) and install another 100A CB in your 200 A (space freed up, etc) to feed the garage. However, you don't want to have more than three molded-case breakers in series or you will mess up your selective coordination -- that is, the cardinal sequence of tripping closest to a fault.
That means if you do us a 100 A subpanel, and you feed it from the 200A panel via a 100A CB (ok - you now have 200 and a 100 in series) you can't put another 100A CB in the 100 A panel to feed the garage panel (now you have 200-100-100). However, install a 100 A in the 200A panel and then your sequence become 200-100-Whatever Branch Value (i.e., 15/20/30, etc)

You don't need a "Main CB" in the nippled panel

 

[Charles (in GA)]

Sounds like all you need to do is pull out that 30 amp double pole breaker you have the welder on (the former cooktop breaker) and put a 100 amp in its place and run conductors to the garage panel. Nothing else to do.

Charles

 

[tundradude]

Sounds like all you need to do is pull out that 30 amp double pole breaker you have the welder on (the former cooktop breaker) and put a 100 amp in its place and run conductors to the garage panel. Nothing else to do.

Charles

Not that easy. A 30amp breaker takes up 2 slots in the panel. A 100 amp breaker takes up 8. (Stablock - Federal Pioneer anyway) And he said his panel is full.

Only solution is to free up the required slots if you want to get 100 amps out of it.

 

[LoneGunman]

Not that easy. A 30amp breaker takes up 2 slots in the panel. A 100 amp breaker takes up 8. (Stablock - Federal Pioneer anyway) And he said his panel is full.

Only solution is to free up the required slots if you want to get 100 amps out of it.

The majority of the panels in use in the United States only require two open spaces for a 100A single phase breaker.

 

[dwilliams35]

He said it was a cutler hammer: that 100 will take the same space as a 60.

Federal always did goofy stuff like that, right up until they stopped making them because they don't trip.

 

[tundradude]

Well, I have a cutler hammer panel in the garage. It has a 60 amp breaker in it that takes up 4 slots. How can a 100 amp breaker take up only 2?

 

[LoneGunman]

Well, I have a cutler hammer panel in the garage. It has a 60 amp breaker in it that takes up 4 slots. How can a 100 amp breaker take up only 2?

If a 30,40,50 ETC takes two spots why do you think a 100 amp breaker would be any different? and like I said, that's what is in MOST houses, you have the oddball panel breaker/panel combo.

 

[Charles (in GA)]

The Cutler Hammer panels and breakers Home Depot has here use only two slots for a double pole (240v) breaker, no matter the amp size. The HD here has both the BR (former Bryant, which is "interchangable" with Siemens, Murry, etc) and the CH type breakers which are CH's own propriety type.

Charles

 

[BigChevy80]

Not that easy. A 30amp breaker takes up 2 slots in the panel. A 100 amp breaker takes up 8. (Stablock - Federal Pioneer anyway) And he said his panel is full.

Only solution is to free up the required slots if you want to get 100 amps out of it.

FPE did stupid stuff like that. Probably one of the reasons they no longer exist. That, and the fact that their breakers were garbage. Next best thing to a Zinsco...

Any normal panel will use 2 slots for a 240v breaker.

 

[Torque1st]

He could also just replace the entire panel with a larger panel if available and use his existing breakers.

 

[tundradude]

OK ... I see where you guys are going with this. It's all in the way you look at it. I forgot my cutler hammer panel was like that.

This to me, is two slots.

As opposed to ....

or ....

Sorry for any confusion. Sorry to highjack this thread. Carry on ....

 

[Torque1st]

OK ... I see where you guys are going with this. It's all in the way you look at it. I forgot my cutler hammer panel was like that.

This to me, is two slots.

As opposed to ....

or ....

Sorry for any confusion. Sorry to highjack this thread. Carry on ....

That top picture is one slot. The others are two slots. Each slot is roughly 1" wide on most panels.