Panel question

Jody Humbert · 03-26-2010, 11:51 AM

Had a 200 amp panel with a 200 amp disconnect in the panel. Service entrance wires were only rated for 100 amp. On the exterior of the house was a 100 amp disconnect between the meter and the panel on the inside. Wires coming from the pole were rated for 100 amp. Why would you install a 200 amp panel but only maintain the 100 amp service by having the smaller service wires and disconnect? Thank you for your thoughts ahead of time.

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Jody Humbert · 03-26-2010, 11:54 AM

Ooops. Forgot the photos.

**Dom D'Agostino** · 03-26-2010, 11:55 AM

A couple of common reasons:

1. It's easier to install the "larger" panel now and plan for future upgrades.
2. It's all they had on the truck the day of the install.

Dom.

**Jim Port** · 03-26-2010, 11:58 AM

Looks like they needed more breaker spaces than a 100 amp panel would allow. Avoided adding a subpanel too.

**ken horak** · 03-26-2010, 02:58 PM

OK Folks , Time for a Quiz !

In the photo of the main Service Disconnecting means, (The photo on the right, the Enclosed Breaker), I will assume that the service entrance conductors are those on the bottom right of the disconnect and the cable leaving the top of enclosed breaker is the Feeder to the interior panel.

I see 1 clear violation ,(possibly 3 violations total) in that enclosed breaker.

I'll give you a hint :
It's not that fuzzy stuff sticking to the top of the breaker

I am looking at article 250 in the NEC.

It's not about the use or lack of a bonding bushing/bonding lock nut/ bonding wedge either

Hummmmmm ? Article 250 ? Grounding and Bonding ?

**Jerry Peck** · 03-26-2010, 03:57 PM

Originally Posted by Jody Humbert

Had a 200 amp panel with a 200 amp disconnect in the panel. Service entrance wires were only rated for 100 amp. On the exterior of the house was a 100 amp disconnect between the meter and the panel on the inside. Wires coming from the pole were rated for 100 amp. Why would you install a 200 amp panel but only maintain the 100 amp service by having the smaller service wires and disconnect? Thank you for your thoughts ahead of time.

Jody,

Here is the problem in what I see as the answer to you having the answer to your question:
"Had a 200 amp panel with a 200 amp disconnect in the panel. Service entrance wires were only rated for 100 amp."

From your description, "the FEEDER wires were only 100 amp rated" would be the correct way to say it. I.e., the conductors from the service equipment OUTSIDE to the panel INSIDE are the feeder conductors, not the service entrance conductors, and those are the conductors you are referring to - correct?

"On the exterior of the house was a 100 amp disconnect between the meter and the panel on the inside."

That 100 amp disconnect is the service equipment and the main disconnect, thus it does not matter how large of a panel is installed downstream of that, the maximum load is going to be 100 amps, which means 100 amp feeders to a 200 amp panel is okay.

Wires coming from the pole were rated for 100 amp.

You are referring to the overhead service drop? If so, they have different ampacity ratings (much higher) than service entrance or feeder conductors have.

Why would you install a 200 amp panel but only maintain the 100 amp service by having the smaller service wires and disconnect?

To get more circuits, but not more circuit capacity (not more ampacity).

**ken horak** · 03-26-2010, 07:24 PM

What no takers on my quiz ??

Roger Frazee · 03-26-2010, 07:33 PM

Originally Posted by ken horak

What no takers on my quiz ??

I don't see the main bonding jumper neutral and ground appear to be isolated.

No clamp on the ser cable where it enters the service equipment enclosure but it appears to be entering through conduit. Still looking for the third violation. Are you wanting a hold down for the breaker?

Roger Frazee · 03-26-2010, 07:46 PM

Grounding lug bottom left might be incorrect installation.

**Brandon Whitmore** · 03-26-2010, 07:52 PM

What no takers on my quiz ??

Well, if that is the service equipment, then the neutral and ground should not be isolated.

I'm waiting to hear what the 2nd and third are.......

**ken horak** · 03-27-2010, 05:23 AM

OK 2 of the 3 have been discovered!

1- where is the required bonding jumper ( bond screw) in the Neutral bar ?

2 - The installation of the grounding lug is an illegal install. It appears that there is a self tapping screw holding both the lug and the ground bar in.

OK another hint :
The 3rd violation (and maybe 4th) could be created when they correct the bonding jumper issue ( item # 1 above) I'm still looking in article 250.

**paul hardy** · 03-27-2010, 01:47 PM

I would look to see if that breaker is secured with a screw or clip because the line side is attached to the breaker.Also the grounding electrode conductor should be on the same bar as the grounded conductor not using the enclosure for the connection.

**ken horak** · 03-27-2010, 02:20 PM

An enclosed breaker like that one has the breaker bolted in place.

Secondly -

You have mentioned the 3rd possible violation !

I say possible violation because it depends on HOW they bond the neutral bar. If they use a bonding screw then yes the grounding electrode conductor must land on the on the same bar as the neutral.
The bonding screw is have a green finish that shalll be visable when the screw is installed.
If they chose to install a bonding jumper that is a wire or bus bar then they are allowed to land the Grounding electrode conductor on the grounding terminals. If using a wire as the bonding jumper it shall be sized using table 250.66

The code sections are 250.24 & 250.28 in the 2008 NEC