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-   -   Sub panel size (http://www.diychatroom.com/f18/sub-panel-size-13255/)

sluggermike 11-10-2007 02:40 PM

Sub panel size
 
I have a 100 amp main panel and I want to put in a sub panel for an Endless pool. The requirements are one 30 amp 240v breaker and two or three 15 amp 120V breakers. I'm wondering how big a breaker I can put in the main panel for the sub panel? I can seem to find anything in the books that I have about it.

Andy in ATL 11-10-2007 04:32 PM

You could put in a 200A if ya wanted. The sub would be protected by the main and the 200A would simply be a disconnect.

I'd put in a 50 or a 60.

goose134 11-11-2007 01:38 AM

220-10 General. The computed load of a feeder or service shall not be less than the sum of the loads on the branch circuits supplied...

a reference for the 50 or 60 answer.

Stubbie 11-11-2007 02:26 AM

Put in a 6 or 12 circuit 100 amp panel. The minimum you would be allowed by code is 60 amps.

Stubbie

Andy in ATL 11-11-2007 07:57 AM

Learn me something here... Why can't I feed a sub with a 50?

What is the ACTUAL load on the tub. I don't just start adding up breakers, do I? I need actual consumption info.

Edit to add: I know i'm wrong, here. I'm lookin for code reference on the 60A.

Stubbie 11-11-2007 01:07 PM

Andy look at NEC 225.29 A thru D (Disconnect rating for feeders).... then compare to the posters requirements for the pool.

The same is true for Services see NEC 230.79

Stubbie 11-11-2007 01:57 PM

See if this helps....We are talking about the disconnect means which may or may not be the ocpd protecting the feeder. If I'm feeding a sub-panel indoors or outdoors and I have 4 circuits operating out of that subpanel my disconnect rating must be a minimum rating of 60 amps. If I have a OCPD protecting a feeder to a mlo sub then it is also the disconnect and must be 60 amps minimum. However if I have a disconnect at the sub in the form of a main breaker or a remote disconnect for a mlo subpanel that meets the minimum disconnect rating for the # of branch circuits served by the sub-panel the ocpd in the main panel is no longer the disconnect for the sub it is simply the ocpd for the feeder. In this case the feeder can be 50 amps or 30 or 40 anything you want depending on the load calcultaion to the equipment to be served. Disconnects and ocpd are not always the same thing. Could be wrong on this but thats the understanding I have always held.

Stubbie

Andy in ATL 11-11-2007 02:14 PM

Thanks Stubbie, That clears it up. Apples and oranges.:laughing: I don't have any argument that the disconecting means must be rated for 60A. I also concur that if I was the OP a 100A rated panel with a 100A breaker would be the way I would do it.

Stubbie 11-11-2007 03:02 PM

Well first I'm not real sure what an endless pool is....I think it is an excercise pool that produces a current that you swim against. Pretty small in size like 10' by 15' I think.

A lot more needs to be known before we can be specific with the op's question.

Also 100 amp main panels likely will not allow 100 amp breakers to be installed on the bus stabs....known as the buss stab rating.... (You know this but just being clear)
So a smaller ocpd and feeder may be in order in this particular case. This is a pool so we need more info.

Slugger is pretty knowledgeable so I'm sure he is aware that pool code must be followed for this installation.

If the pool maker states 1 30amp 240V and 3 15amp 120 volt and looking at it at 80% loaded (all breakers pulling their load current) that would be right at a 60 amp feeder capacity. It is a close call IMO so we need more information on the load requirements for the pool.

sluggermike 11-11-2007 03:28 PM

Stubbie, you are right about the Endless pool. It is like a tread mill in the water. I will be getting more info on the electrical requirement and let you know. Thanks

bjones 11-11-2007 03:46 PM

Requirements
 
Slugger is my dad, he's helping me with the install (nice guy, huh?)

The city will permit it as an above ground spa instead of a pool.

Endless pools says that all circuits have to be individually GFCI protected but that you can not use a GFCI main breaker for a sub-panel. Does that mean you can't use a GFCI breaker to feed the sub-panel or that you can't use GFCI breakers in the sub-panel?

Circuits:
1 x 220v 30A
2 x 110v 20A
1 x 110v 5A
There is an optional additional 1 x 220 30A but it isn't required since the 2 220 30A units don't go on at the same time.

Thanks!

Andy in ATL 11-11-2007 04:42 PM

Slugger's kid,

It means you can't use a GFCI breaker to feed the sub panel. They want individual GFCI breakers in the sub.

You list 1- 110V 5A as one of the circuits. This is confusing.:huh: Stubbie!?!

Welcome to the forum

Stubbie 11-11-2007 04:58 PM

It's a typo he meant 15

bjones 11-11-2007 05:43 PM

Sorry, yes it was a typo. It should have been 15A and not 5A :)

Andy in ATL 11-11-2007 05:50 PM

My head was about to explode.:laughing:


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