225.39 (d) - Electrician Talk - Professional Electrical Contractors Forum

Gamit · 04-19-2012, 08:47 PM

I am going to run a feeder out for a sub panel in a detached garage. I want to run a 50 amp circuit which is fine as long as the disconnect means in the sub panel is a 60 amp breaker. Correct?

BuzzKill · 04-19-2012, 09:10 PM

Quote:

Originally Posted by Gamit

I am going to run a feeder out for a sub panel in a detached garage. I want to run a 50 amp circuit which is fine as long as the disconnect means in the sub panel is a 60 amp breaker. Correct?

uh, no..the 50 amp circuit needs a 50 amp breaker in the main panel..you can put a 200 amp disco outside, but the feeder should be rated at 50 amps.

Gamit · 04-19-2012, 09:15 PM

Quote:

Originally Posted by BuzzKill

uh, no..the 50 amp circuit needs a 50 amp breaker in the main panel..you can put a 200 amp disco outside, but the feeder should be rated at 50 amps.

That's what I was implying. It could be number 8 wire protected by a 40 Amp circuit and with at least three branch circuits it would need at least a 60 Amp disconnect in sub panel.

nrp3 · 04-19-2012, 09:21 PM

Why the 60? You could have back fed 40 with a hold down kit.

BuzzKill · 04-19-2012, 09:24 PM

Quote:

Originally Posted by Gamit

That's what I was implying. It could be number 8 wire protected by a 40 Amp circuit and with at least three branch circuits it would need at least a 60 Amp disconnect in sub panel.

you're losing me..

Gamit · 04-19-2012, 09:26 PM

Quote:

Originally Posted by nrp3

Why the 60? You could have back fed 40 with a hold down kit.

That's what the article requires that when you have three or more branch circuits on a detached structure the disconnecting means must be rated at a minimum of 60 Amps.

Gamit · 04-19-2012, 09:28 PM

Quote:

Originally Posted by BuzzKill

you're losing me..

How?

nrp3 · 04-19-2012, 09:34 PM

So what you are saying is that's what 225 39 calls for? I'll drag the book out in the morning.

Gamit · 04-19-2012, 09:37 PM

Quote:

Originally Posted by nrp3

So what you are saying is that's what 225 39 calls for? I'll drag the book out in the morning.

That's the whole reason for post to confirm. But yes

3xdad · 04-19-2012, 09:40 PM

Quote:

Originally Posted by Gamit

I am going to run a feeder out for a sub panel in a detached garage. I want to run a 50 amp circuit which is fine as long as the disconnect means in the sub panel is a 60 amp breaker. Correct?

Think of it like this, as long as the rating of your disconnect (not breaker) is not less than 60 amp. You could run your 50A feeder and land in a 100A rated MLO panel with no more than 6 throws if you want.

Keep in mind you are feeding a separate structure and need an electrode.

Gamit · 04-19-2012, 09:45 PM

Quote:

Originally Posted by 3xdad

Think of it like this, as long as the rating of your disconnect (not breaker) is not less than 60 amp. You could run your 50A feeder and land in a 100A rated MLO panel with no more than 6 throws if you want.

Keep in mind you are feeding a separate structure and need an electrode.

That is not what the article is saying? I will have 4 branch circuits in garage on a 50 Amp feeder. The article specifies that the disconnecting means must be 60 Amp rated at very least and 30 Amp rated with 2 circuits.

Gamit · 04-19-2012, 09:46 PM

Quote:

Originally Posted by Gamit

That is not what the article is saying? I will have 4 branch circuits in garage on a 50 Amp feeder. The article specifies that the disconnecting means must be 60 Amp rated at very least and 30 Amp rated with 2 circuits.

So I do not think you could use a MLO only panel in a detached structure but would need either a 30 or 60 Amp rated disconnect

**Dennis Alwon** · 04-19-2012, 10:01 PM

Quote:

Originally Posted by Gamit

So I do not think you could use a MLO only panel in a detached structure but would need either a 30 or 60 Amp rated disconnect

I agree that the article states the disconnect must be 60 amps- who knows what that reasoning is??? However you can have a MLO panel if it is service rated and you have no more than 6 disconnects. So you could have 3 20 amp breakers and that would give you the 60 amps needed to satisfy 225.39(D)

**Dennis Alwon** · 04-19-2012, 10:02 PM

Most MLO panels require the main breaker kit to make it service rated.

Gamit · 04-19-2012, 10:04 PM

Quote:

Originally Posted by Dennis Alwon

I agree that the article states the disconnect must be 60 amps- who knows what that reasoning is??? However you can have a MLO panel if it is service rated and you have no more than 6 disconnects. So you could have 3 20 amp breakers and that would give you the 60 amps needed to satisfy 225.39(D)

Or could I just back feed a 60 Amp breaker in the sub panel and be done with it.Right? This would satisfy the article and I can use as many breakers as I need in compliance with the load calculation of the feeder of course

Gamit · 04-19-2012, 10:08 PM

Quote:

Originally Posted by Gamit

Or could I just back feed a 60 Amp breaker in the sub panel and be done with it.Right? This would satisfy the article and I can use as many breakers as I need in compliance with the load calculation of the feeder of course

Or a small 100 Amp main breaker panel

RIVETER · 04-19-2012, 10:13 PM

Quote:

Originally Posted by Gamit

I am going to run a feeder out for a sub panel in a detached garage. I want to run a 50 amp circuit which is fine as long as the disconnect means in the sub panel is a 60 amp breaker. Correct?

How can a 60 amp breaker suffice a 50 amp circuit?

Gamit · 04-19-2012, 10:18 PM

Quote:

Originally Posted by RIVETER

How can a 60 amp breaker suffice a 50 amp circuit?

The 50 amp circuit is being protected by the 50 Amp breaker in the main panel in house and all the 60 Amp breaker is simply a additional disconnect in the sub panel.

RIVETER · 04-19-2012, 10:19 PM

Quote:

Originally Posted by Gamit

The 50 amp circuit is being protected by the 50 Amp breaker in the main panel in house and all the 60 Amp breaker is simply a additional disconnect in the sub panel.

Why go to 60?

Gamit · 04-19-2012, 10:22 PM

Quote:

Originally Posted by riveter

why go to 60?

225.39 (d)

04-19-2012, 08:47 PM	#1
Gamit Senior Member Join Date: Dec 2009 Location: NJ Posts: 870 Rewards Points: 510	225.39 (d) I am going to run a feeder out for a sub panel in a detached garage. I want to run a 50 amp circuit which is fine as long as the disconnect means in the sub panel is a 60 amp breaker. Correct?

04-19-2012, 10:02 PM	#14
Dennis Alwon Moderator Join Date: May 2009 Location: Chapel Hill, NC Posts: 21,704 Rewards Points: 2,302	Most MLO panels require the main breaker kit to make it service rated. __________________ They say I shot a man named Gray and took his wife to Italy She inherited a million bucks and when she died it came to me I can't help it if I'm lucky

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04-19-2012, 09:21 PM	#4
nrp3 Can't Remember Join Date: Jan 2009 Location: New Hampshire Posts: 10,115 Rewards Points: 1,528	Why the 60? You could have back fed 40 with a hold down kit.

04-19-2012, 09:34 PM	#8
nrp3 Can't Remember Join Date: Jan 2009 Location: New Hampshire Posts: 10,115 Rewards Points: 1,528	So what you are saying is that's what 225 39 calls for? I'll drag the book out in the morning.