# How big of sub panel breaker for 5 15 amp breakers?



## Bkessler (Feb 14, 2007)

bushwickbill said:


> I am adding a sub panel/Load center to a 200 amp panel. The two slots I need for the sub panel breaker have 2 15amp S.P. breakers on them. Plus I need to add three 15 amp S.P. circuits for additional lighting loads. I think I need a 40amp 2 pole breaker, or is that not enough for 5 15 amp circuits?
> Any and all advice would be great?:thumbsup:


It depends on the total load of the circuits. When I am just making room to add more circuit's I usually install a 60.


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## Dennis Alwon (May 9, 2009)

bushwickbill said:


> I am adding a sub panel/Load center to a 200 amp panel. The two slots I need for the sub panel breaker have 2 15amp S.P. breakers on them. Plus I need to add three 15 amp S.P. circuits for additional lighting loads. I think I need a 40amp 2 pole breaker, or is that not enough for 5 15 amp circuits?
> Any and all advice would be great?:thumbsup:


More likely than not the DP 40 is enough but without knowing the loads it is a guess. Run a 60 amp wire and leave room for expansion.


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## BBQ (Nov 16, 2010)

15 amp x 120 volts = 1800 watts x 5 circuits = 9000 watts / 240 volts = 37.5 amp breaker. 

The 2 pole 40 is likely bigger than it needs to be, but I would likely use what ever size the panel is, I assume at least a 60 amp panel?


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## bushwickbill (Jan 17, 2010)

I am deciding the size of the load center or sub panel on the size of the breaker feeding it. I will probably opt for a 8/4 slot load center. I don't know what the loads are going to be exactly. I just know I need to put the two 15 Amp circuits in that I am removing from the main panel to make room, Then I am adding three extra circuits. One is for 9-11 pot lights for the living room. Another is for a bathroom Heat lamp/Fan combo unit. And the another is for a attic fan that is only 4.8 amps, But being a motor load I want to keep it off anything else just to be safe and by the book.
http://www.sea.siemens.com/us/inter...sidential/docs_LoadCenters/E0816ML1125FCU.jpg

Something similar to this i think will do the job fine.
Anyone have advice on picking small load centers?
BTW, I like the idea to run 60 Amp wire on a 40 Amp 2 P breaker for future loads?


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## doubleoh7 (Dec 5, 2009)

bushwickbill said:


> I am deciding the size of the load center or sub panel on the size of the breaker feeding it. I will probably opt for a 8/4 slot load center. I don't know what the loads are going to be exactly. I just know I need to put the two 15 Amp circuits in that I am removing from the main panel to make room, Then I am adding three extra circuits. One is for 9-11 pot lights for the living room. Another is for a bathroom Heat lamp/Fan combo unit. And the another is for a attic fan that is only 4.8 amps, But being a motor load I want to keep it off anything else just to be safe and by the book.
> http://www.sea.siemens.com/us/inter...sidential/docs_LoadCenters/E0816ML1125FCU.jpg
> 
> Something similar to this i think will do the job fine.
> ...


Why not just buy a 60? It will cost the same.


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## guest (Feb 21, 2009)

Two words: 

Load Calc. :thumbsup:

Otherwise a 60 amp wire/breaker is a good choice for future expansion.


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## HARRY304E (Sep 15, 2010)

bushwickbill said:


> I am adding a sub panel/Load center to a 200 amp panel. The two slots I need for the sub panel breaker have 2 15amp S.P. breakers on them. Plus I need to add three 15 amp S.P. circuits for additional lighting loads. I think I need a 40amp 2 pole breaker, or is that not enough for 5 15 amp circuits?
> Any and all advice would be great?:thumbsup:


Just slap up a 60 amp panel:thumbup:


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## Jlarson (Jun 28, 2009)

I'd go the 60 amp route.


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## wayne g (Nov 28, 2010)

6/3 SER or 6/3 romex with a 2pole 60 amp breaker to feed your (unknown load) in your new sub-panel location should indeed do the job & probaly leave room for furture use. :thumbsup::thumbsup:


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## wayne g (Nov 28, 2010)

Like your route.


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## BIGRED (Jan 22, 2007)

wayne g said:


> 6/3 SER or 6/3 romex with a 2pole 60 amp breaker to feed your (unknown load) in your new sub-panel location should indeed do the job & probaly leave room for furture use. :thumbsup::thumbsup:


I would go 4/3 SER or 6/3 romex for 60 amp.


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## BBQ (Nov 16, 2010)

wayne g said:


> 6/3 SER or 6/3 romex with a 2pole 60 amp breaker to feed your (unknown load) in your new sub-panel location should indeed do the job & probaly leave room for furture use. :thumbsup::thumbsup:



Unless you are using copper SE under the 2008 NEC the max breaker for 6/3 SER used as a indoor branch circuit would be 40 amps. 

Under the 2005 NEC or before the max breaker for 6/3 SER used as a indoor branch circuit would be 50 amps.


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## brian john (Mar 11, 2007)

What I have always done is, whether is is a 60, 100 or 200, if there is room I always order the one with the max spaces in that size. Just a personal thing.


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## Cletis (Aug 20, 2010)

*Sub Panel*

Personally, I'd just run a 100 amp rated 10/20 space load center, 6-3 Cu stranded thhn through nipple, on a 60 amp OCPD and be done with it. That way your not putting in sub panels off sub-panels down the road. It's literally only maybe $20 more and your done with it!


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## kwired (Dec 20, 2009)

bushwickbill said:


> ...One is for 9-11 pot lights for the living room. Another is for a bathroom Heat lamp/Fan combo unit. And the another is for a attic fan that is only 4.8 amps, But being a motor load I want to keep it off anything else just to be safe and by the book.
> ...
> Anyone have advice on picking small load centers?
> BTW, I like the idea to run 60 Amp wire on a 40 Amp 2 P breaker for future loads?


 
You want to keep the 4.8 amp motor off anything else to be safe from what? and by what book?

That fan could be on with the living room lights you mention according to NEC as long as both together are not more than the rating of the circuit.

I have never seen a 60 amp panel besides the old fuse boxes that were installed years ago or maybe a two or three pole breaker enclosure intended for installation of a single breaker. I have seen many 100 or 125 amp panels supplied by a 60 or any other overcurrent device size under 100 amp.


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## 10492 (Jan 4, 2010)

BBQ said:


> Unless you are using copper SE under the 2008 NEC the max breaker for 6/3 SER used as a indoor branch circuit would be 40 amps.
> 
> Under the 2005 NEC or before the max breaker for 6/3 SER used as a indoor branch circuit would be 50 amps.


The OP is talking about a feeder, not a range branch circuit.


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## BBQ (Nov 16, 2010)

Dnkldorf said:


> The OP is talking about a feeder, not a range branch circuit.



That does not change anything.


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## 10492 (Jan 4, 2010)

BBQ said:


> That does not change anything.


No kidding, the same rule applies to feeders as it does to branch circuits, under your statements a couple of posts up?


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## jwjrw (Jan 14, 2010)

For general use circuits I will install a 12/24 fed with 60 amps. Our supply house has them for 33.00.


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## arem (Dec 22, 2010)

anyone how is asking about the loads is stupid.

your main is protected with the 200 amp, just pick a sub panel 60 or 100 , add any loads you want to sub.


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## TOOL_5150 (Aug 27, 2007)

Uhm... I was under the impression that you can only put 50A through 6/3 romex.


~Matt


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## jwjrw (Jan 14, 2010)

TOOL_5150 said:


> Uhm... I was under the impression that you can only put 50A through 6/3 romex.
> 
> 
> ~Matt




#6 romex at 60 deg is 55a. Next size up rule lets you fuse it at 60.


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## Speedy Petey (Jan 10, 2007)

arem said:


> anyone how is asking about the loads is stupid.
> 
> your main is protected with the 200 amp, just pick a sub panel 60 or 100 , add any loads you want to sub.


Um....this is not what I would call an exemplary first post. It is insulting and not accurate.

You may want to re-think your posting style.


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## jwjrw (Jan 14, 2010)

Speedy Petey said:


> Um....this is not what I would call an exemplary first post. It is insulting and not accurate.
> 
> You may want to re-think your posting style.




I think it was just as intelligent as Jlarsons first post......(probably most of mine too)....:whistling2::laughing:



J/K Speedy.....:thumbsup:


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## BBQ (Nov 16, 2010)

arem said:


> anyone how is asking about the loads is stupid.


You are not really an electrician are you?

More likely a Craig's list handyman.


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## 220/221 (Sep 25, 2007)

arem said:


> anyone how is asking about the loads is stupid.
> 
> your main is protected with the 200 amp, just pick a sub panel 60 or 100 , add any loads you want to sub.


 
When it trips, you've added too much :laughing:


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## TOOL_5150 (Aug 27, 2007)

jwjrw said:


> #6 romex at 60 deg is 55a. Next size up rule lets you fuse it at 60.


OK, so i was right about it being 55A, whats the 2005 code ref for the next size up rule? Or 2008.. whatevers easier.

~Matt


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## jwjrw (Jan 14, 2010)

TOOL_5150 said:


> OK, so i was right about it being 55A, whats the 2005 code ref for the next size up rule? Or 2008.. whatevers easier.
> 
> ~Matt



240.4 Protection of Conductors. Conductors, other than
flexible cords, flexible cables, and fixture wires, shall be
protected against overcurrent in accordance with their ampacities
specified in 310.15, unless otherwise permitted or
required in 240.4(A) through (G).

(B) Overcurrent Devices Rated 800 Amperes or Less.
The next higher standard overcurrent device rating (above
the ampacity of the conductors being protected) shall be
permitted to be used, provided all of the following conditions
are met:
(1) The conductors being protected are not part of a branch
circuit supplying more than one receptacle for cordand-
plug-connected portable loads.
(2) The ampacity of the conductors does not correspond
with the standard ampere rating of a fuse or a circuit
breaker without overload trip adjustments above its rating
(but that shall be permitted to have other trip or
rating adjustments).
(3) The next higher standard rating selected does not exceed
800 amperes


That's 2011 but I bet it is the same.


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## TOOL_5150 (Aug 27, 2007)

jwjrw said:


> 240.4 Protection of Conductors. Conductors, other than............
> That's 2011 but I bet it is the same.


Thanks :thumbsup:


~Matt


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## jwjrw (Jan 14, 2010)

TOOL_5150 said:


> Thanks :thumbsup:
> 
> 
> ~Matt



I try to post accurate helpful information at least once a day so the mods can't say I'm a full time troll.:whistling2::laughing:
I forgot ET political dissident....


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## TOOL_5150 (Aug 27, 2007)

jwjrw said:


> 240.4 Protection of Conductors. Conductors, other than
> flexible cords, flexible cables, and fixture wires, shall be
> protected against overcurrent in accordance with their ampacities
> specified in 310.15, unless otherwise permitted or
> ...


So to expand on this - to make sure I really understand it - What it is saying that if I either have a feeder, OR if I have a branch circuit that has 1 receptacle, I can up-size the breaker in either instance if there isn't a standard breaker size available?


~Matt


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## TOOL_5150 (Aug 27, 2007)

jwjrw said:


> I try to post accurate helpful information at least once a day so the mods can't say I'm a full time troll.:whistling2::laughing:


:thumbup::laughing:

~Matt


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## jwjrw (Jan 14, 2010)

TOOL_5150 said:


> So to expand on this - to make sure I really understand it - What it is saying that if I either have a feeder, OR if I have a branch circuit that has 1 receptacle, I can up-size the breaker in either instance if there isn't a standard breaker size available?
> 
> 
> ~Matt



Seems to say that. I have only used this rule for feeders. Never really read the part about cord and plug single receptacle circuit.


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## BBQ (Nov 16, 2010)

TOOL_5150 said:


> So to expand on this - to make sure I really understand it - What it is saying that if I either have a feeder, OR if I have a branch circuit that has 1 receptacle, I can up-size the breaker in either instance if there isn't a standard breaker size available?
> 
> 
> ~Matt


Yes, see 240.6 for standard sizes.

Also this does not mean you can load the conductor more than the 310.16 rating.


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## TOOL_5150 (Aug 27, 2007)

BBQ said:


> Yes, see 240.6 for standard sizes.
> 
> Also this does not mean you can load the conductor more than the 310.16 rating.


Thanks fellas.. I knew that code existed, but never knew the specifics. Learned something new today :thumbsup:

~Matt


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## jbfan (Jan 22, 2007)

To the first poster, check the heater/ fan to make sure it is not requiring a 20 amp circuit.


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