Question on isolating ground in a sub panel

[rwilner]

Gj friends,
I'm wiring a subpanel for my attached 3 car. I have a square d homeline main breaker panel I got at the depot for short $, even came with a few breakers. I know I could have used a main lug panel, but thought it would be convenient to have the breaker as a disconnect.

Anyway: I bought the ground bar kit at the depot. It didn't come with isolators. They didn't sell an isolation kit.

Anyone use this panel before? How can I isolate the ground from the neutral..or is the neutral already isolated from the box?

 

[pattenp]

The ground bar connected directly to the panel. The neutral bar is isolated on plastic standoffs. There is a bonding screw that needs to be removed from the neutral bar.

 

[bczygan]

There is a green screw punched through a square piece of paper that comes with the panel, usually stuck in a hole near the main breaker. It's purpose is to bond neutral bar to the box. You don't want to do this in a sub panel. Just take it out and don't use it.

Install a ground bar kit in a convenient location in the panel and connect all your grounds to that and your neutrals to the other existing neutral bars in the panel. The ground bar is bonded to the box.

Bill

 

[zmaxmotorsports]

The ground bar connected directly to the panel. The neutral bar is isolated on plastic standoffs. There is a bonding screw that needs to be removed from the neutral bar.

Just don't install the bonding screw,no need to remove it.
This stupid phone has a mind of its own some days,glad I looked at this post again.

 

[rwilner]

Perfect. I didn't realize the neutral buss was isolated from the box.

I guess I could have screwed it all together and checked with my meter - but I knew you guys would know!

Sent from my Nexus 7 using Tapatalk

 

[pattenp]

Just don't inot all the bondingredients screw,then there's no need to remove it.

If my memory is correct the homeline main breaker panel comes with the neutral bar bonded.

 

[wyliesdiesels]

Perfect. I didn't realize the neutral buss was isolated from the box.

I guess I could have screwed it all together and checked with my meter - but I knew you guys would know!

Sent from my Nexus 7 using Tapatalk

Neutral bar is the one that needs to be isolated NOT the ground bar.

U dont want an isolated ground bar.

 

[sberry]

I was going to say the same thing, think of this more as insulated neutral.

 

[tyme2par4]

If my memory is correct the homeline main breaker panel comes with the neutral bar bonded.

Nope. I've got one sitting in my basement that I'm installing tomorrow.
As bczygan said, it comes with a bonding screw. The neutral bars are isolated until you install that screw.
It comes with 2 neutral bars, and no separate ground bar, that's why he had to buy the ground bar kit.

 

[pattenp]

Nope. I've got one sitting in my basement that I'm installing tomorrow.
As bczygan said, it comes with a bonding screw. The neutral bars are isolated until you install that screw.
It comes with 2 neutral bars, and no separate ground bar, that's why he had to buy the ground bar kit.

I know they don't come with ground bars, but the last Square-D HL main breaker panel I installed I thought it came with the neutral bar bonded and the bonding strap needed to be removed. I was just going on what I thought I remembered. Bottom line is the neutral bar is to be isolated from ground in a sub-panel.

 

[bczygan]

I don't know about Homeline, but I have 2 QO panels, and the bonding screws were stuck in a hole in one of the neutral bars. Don't know if they were the right place to be bonding things, they weren't screwed in tight, but they weren't loose in the panel box. I'm not sure where they go anyway.

Bill

 

[rwilner]

Guys
I'm hijacking my own thread - but it's OK to have the 100 a breaker in my main panel feed the 100a breaker in my sub panel, right?

(The only reason I got the main breaker version was to use the breaker as a disconnect.)

Sent from my Nexus 7 using Tapatalk

 

[wyliesdiesels]

Guys
I'm hijacking my own thread - but it's OK to have the 100 a breaker in my main panel feed the 100a breaker in my sub panel, right?

(The only reason I got the main breaker version was to use the breaker as a disconnect.)

Sent from my Nexus 7 using Tapatalk

Yeah theres nothing wrong with doing that.

What size wire?

 

[rwilner]

Wire is #2 aluminum ser, xhhw-2. Per NEC 310.15b, should be good for 100A

 

[pattenp]

Wire is #2 aluminum ser, xhhw-2. Per NEC 310.15b, should be good for 100A

Nope. You need to use the 75deg column. 90A is the max breaker. Also if the SER is run for some distance in insulation you need to use the 60deg column which is 75A.

 

[wyliesdiesels]

Wire is #2 aluminum ser, xhhw-2. Per NEC 310.15b, should be good for 100A

People misunderstand the 90* c column in table 310.15(b)(16) all the time.

It is for derating purposes only.

The only exception in regards to #2 Al on a 100a breaker is if it feeds the entire load of a dwelling.

So breaker ratings need to be as pattenp said.

 

[pattenp]

To add to what wylie said the temp rating on devices such as the breaker is 60/75deg C so you aren't to use amp rating at 90deg C unless derating the wires ampacity.

 

[rwilner]

Nope. You need to use the 75deg column. 90A is the max breaker. Also if the SER is run for some distance in insulation you need to use the 60deg column which is 75A.

Using a 90a breaker us fine, but - can you explain why I use the 75 degree column?

For xhhw it's clear 75 deg is the column to use, but xhhw-2 is listed in the 90 deg column.

 

[wyliesdiesels]

Using a 90a breaker us fine, but - can you explain why I use the 75 degree column?

For xhhw it's clear 75 deg is the column to use, but xhhw-2 is listed in the 90 deg column.

he already explained it. see above

 

[rwilner]

he already explained it. see above

Yep - just checked the breaker rating, it's 75 deg c.

Guess I'll go swap it for a 90! Thanks guys.

 

[zmaxmotorsports]

If my memory is correct the homeline main breaker panel comes with the neutral bar bonded.

Nope,seperate screw comes with it.

 

[zmaxmotorsports]

Guys
I'm hijacking my own thread - but it's OK to have the 100 a breaker in my main panel feed the 100a breaker in my sub panel, right?

(The only reason I got the main breaker version was to use the breaker as a disconnect.)

Sent from my Nexus 7 using Tapatalk

It depends on what you mean by having the 100 a main breaker feeding your sub pan.
You can install a 100 2p breaker seperate from the main to the feed the sub,but you can't just tap into your 100 a main to feed the other panel.

 

[pattenp]

Nope,seperate screw comes with it.

Okay, okay, I've been corrected already.

 

[rwilner]

It depends on what you mean by having the 100 a main breaker feeding your sub pan.
You can install a 100 2p breaker seperate from the main to the feed the sub,but you can't just tap into your 100 a main to feed the other panel.

Yes - separate 2 pole breaker.

Main breaker is 200a