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Old 08-01-2011, 04:46 PM   #1
Tim_in_NC
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Default Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

Hi Guys ...

I'm new here and have decided to begin a somewhat small garage renovation so that it feels more like a small shop, and to be able to fit another vette in the garage as well ... with the help of a bendpak lift ...

So, I wanted to start off by adding more electrical outlets/drops in the garage which currently only has 1 electrical outlet ...

I'd like to add about 6-8 (110V) or so outlets around the garage (Used for Refrigerator, 1.6HP compressor, various power tools, neon lights, tv, stereo, bendpak lift, in-window A/C unit, etc...) and then 1 (220V) that I may use for a welder or other gear that demands a 220 ...

Our home came with a 200A Main with 30 circuits but every slot was taken by the original electrician ...

I'd like to add a 100A sub panel and install it in the garage, the mounting location will only be about 6 feet away from the main ...

I plan to wire all the outlets, install the sub panel in the garage, but will most likely have an electrician come in a run the power from the main to the sub, unless I feel that it's definitely too easy for me to pass up ...

So, after looking at the pics that I've added, what do you think is the best way to get power from the main to the sub panel?

Can I simply remove 4 of the 15amp breakers and install 2 tandem 15 amp breaker to replace the 4 that were removed and then install a 100 amp, double pole circuit in the available slot?







Thanks,
TIM

Last edited by Tim_in_NC; 08-01-2011 at 05:14 PM.
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Old 08-01-2011, 04:59 PM   #2
pl_silverado
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

I guess the easiest would be to replace two breakers on either side with tandem breakers, which would free up enough slots for a double pole 100amp to feed your sub panel.



If you think thats bad, you should see mine. I have a siemens 200amp panel, with 100 amp sub panel, and between the two of them, only 4 free slots........and thats just for the house. Apparently the sparky who rewired it thought every single thing needed its own circuit.

You may want to clamp an amp meter on the incoming service when your a/c & what not is running to see how much of that 200 amp service is in use, to see whether you'll even be able to add any additional loads.
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Last edited by pl_silverado; 08-01-2011 at 05:02 PM.
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Old 08-01-2011, 05:43 PM   #3
Charles (in GA)
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

That panel only has 30 slots in it. I'll bet its a 30/40 panel. If you look at the info on the door it probably says you can put tandem breakers in the bottom five slots on each side (adding ten breakers, bringing the total up to 40)

In fact, I'm sure it is. Look at the placard, the place where you write what the circuit is for, slots 21 and 22 and below have a dotted line across them, indicating the possibility of two circuits, while slots 19 and 20 and up do not have those dotted lines. You CANNOT install tandem breakers in slots 1 thru 20 but CAN install them in slots 21 thru 30.

Again, check the door placard for info on the max number of circuits allowed.

Charles

Last edited by Charles (in GA); 08-01-2011 at 05:46 PM.
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Old 08-01-2011, 05:56 PM   #4
mrb
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

whats the load youre adding with the garage? Outlets and lights or Big compressor and plasma cutter? 200 amps minus all that electric heat and hwh, plus normal hosue loads and you may not have a ton of capacity left.
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Old 08-01-2011, 06:02 PM   #5
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

You may have a couple of those circuits than can be moved to the new sub panel.
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Old 08-01-2011, 06:18 PM   #6
Tim_in_NC
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

Quote:
Originally Posted by Charles (in GA) View Post
That panel only has 30 slots in it. I'll bet its a 30/40 panel. If you look at the info on the door it probably says you can put tandem breakers in the bottom five slots on each side (adding ten breakers, bringing the total up to 40)

In fact, I'm sure it is. Look at the placard, the place where you write what the circuit is for, slots 21 and 22 and below have a dotted line across them, indicating the possibility of two circuits, while slots 19 and 20 and up do not have those dotted lines. You CANNOT install tandem breakers in slots 1 thru 20 but CAN install them in slots 21 thru 30.

Again, check the door placard for info on the max number of circuits allowed.

Charles
You're correct, slots 21-30 will accommodate tandems ... the other will not
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Old 08-01-2011, 06:21 PM   #7
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Originally Posted by pattenp View Post
You may have a couple of those circuits than can be moved to the new sub panel.
why? too much trouble. reuse the removed breakers in the new subpanel and your net cost for the two tandems needed is ~$12, no work other than swapping the breakers, and you have the 2 needed empty spaces.
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Old 08-01-2011, 06:23 PM   #8
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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whats the load youre adding with the garage? Outlets and lights or Big compressor and plasma cutter? 200 amps minus all that electric heat and hwh, plus normal hosue loads and you may not have a ton of capacity left.
3 or 4 neon lights, refrigerator, bendpak HD-9 lift, 1.6hp craftsman compressor, tv, radio, a few power tools ... and a 220 for a welder down the road ... Not all will be running together ...
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Old 08-01-2011, 06:24 PM   #9
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

Sounds like 2 tandems and a 100a double is the way to go ... correct ...
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Old 08-01-2011, 07:57 PM   #10
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

How big is that hood fan? They don't usually draw much, I might be inclined to combine circuit 17 & 21. Then use one tandem for the washer and garage door opener. That'd free up spaces 21 & 23.

Buy some #2 SER, put it on an 80 amp breaker to feed a main lug panel, I'd say at least 12 spaces or so and you should be set.
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Old 08-01-2011, 08:04 PM   #11
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Originally Posted by Aceman View Post
How big is that hood fan? They don't usually draw much, I might be inclined to combine circuit 17 & 21. Then use one tandem for the washer and garage door opener. That'd free up spaces 21 & 23.

Buy some #2 SER, put it on an 80 amp breaker to feed a main lug panel, I'd say at least 12 spaces or so and you should be set.
Why would you use choose an 80amp over a 100amp?
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Old 08-01-2011, 08:11 PM   #12
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

Because #2 SER is readily available. If you held the 1/0 SER in your hand that you needed to use to get the full 100 amps, I bet you'd understand.

That, and the fact I don't think you need a FULL 100 amps for what you're doing.
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Old 08-01-2011, 09:41 PM   #13
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Originally Posted by Tim_in_NC View Post
Why would you use choose an 80amp over a 100amp?
No he didn't
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Old 08-02-2011, 07:17 AM   #14
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Because #2 SER is readily available. If you held the 1/0 SER in your hand that you needed to use to get the full 100 amps, I bet you'd understand.

That, and the fact I don't think you need a FULL 100 amps for what you're doing.
Thank you for the explanation ... So, I should be set with 2 tandems to combine 4 slots into 2, and a double 80a breaker for the open slot to feed the sub panel ... then use #2 Service Entrance Cable for the connection ... If we were ever interested in added a hot tub, would it be better to go with the 100a option?

When running the outlets in the garage for general usage and small power tools ... do most use a 20a breaker for every 2, 110v electrical outlets? Was thinking of running the compressor & lift off of it's own breaker, I need to check their amperage ...

Last edited by Tim_in_NC; 08-02-2011 at 07:44 AM.
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Old 08-02-2011, 08:50 AM   #15
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Originally Posted by mrb View Post
why? too much trouble. reuse the removed breakers in the new subpanel and your net cost for the two tandems needed is ~$12, no work other than swapping the breakers, and you have the 2 needed empty spaces.
I was just giving another option. I didn't say it was the best one.
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Old 08-02-2011, 09:34 AM   #16
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Originally Posted by Tim_in_NC View Post
When running the outlets in the garage for general usage and small power tools ... do most use a 20a breaker for every 2, 110v electrical outlets? Was thinking of running the compressor & lift off of it's own breaker, I need to check their amperage ...
All depends on the load that you are going to have on the outlets as to how many you have on a circuit. In most cases you can do more that two. In my garage I put 5 outlets on each 20A circuit. As far as the lift and compressor go they should be on their own separate circuits if they are 240v.

Last edited by pattenp; 08-02-2011 at 09:36 AM.
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Old 08-02-2011, 10:16 AM   #17
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

If you are going to put more than 1 circuit for receptacles (I assume a separate circuit for lights) and have multiple receptacles running the length of the wall(s), put every other receptacle on the opposite circuit. Less chance of an overload when using multiple power tools simultaneously like a saw and a vacuum and it is easy to remember ! (That is the way load center back planes are arranged.)

Other than the case I just mentioned, if you have your compressor and lift pump motor on a separate circuit, you almost don't need 2 - 20A circuits in a typical "home" workshop.

PS. Don't forget to buy 20A rated receptacles and to use a 20A GFCI receptacle for the first one in the string !

PPS. The hot tub I took out was on a 50A breaker.
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Old 08-02-2011, 10:49 AM   #18
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

Why 20A receptacles? Do you have equipment with 20A plugs on it? Same goes for GFCI. All 15 amp receptacles can be used on 20 amp circuits unless its a single (not a duplex) receptacle and you only have one on the circuit.
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Old 08-03-2011, 08:01 AM   #19
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Why 20A receptacles? Do you have equipment with 20A plugs on it? Same goes for GFCI. All 15 amp receptacles can be used on 20 amp circuits unless its a single (not a duplex) receptacle and you only have one on the circuit.
Why not ?

I know 120V 20A equipment is not common, but I would feel more comfortable plugging a high current, 120V power tool (compressor) into a 20A receptacle than into a 15A one.

Also I don't think any one makes cheap, "residential", 120V 20A receptacles.
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Old 08-03-2011, 09:23 AM   #20
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Default Re: Looks Like my 200 amp Main is Full ... adding a Sub Panel ...

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Originally Posted by theoldwizard1 View Post
PS. Don't forget to buy 20A rated receptacles and to use a 20A GFCI receptacle for the first one in the string !

PPS. The hot tub I took out was on a 50A breaker.

Wizard ... Here is a drawing that I found online ... when grouping outlets to the same breaker, do I make the 1st outlet a GFCI or all outlets, except for the last one in the chain, GFCI and attach the last one as shown in the pic so that it's fully protected?

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