Electrician Talk banner

1 - 20 of 21 Posts

·
Registered
Joined
·
49 Posts
Discussion Starter #1 (Edited)
As the title states I am creating this post because I would like to better understand how a panel I came across is designed.

The panel is a Square D QO Load center, Model# QO-16-408, Series: A-10.
I tried looking up information on the panel via google but couldn't find any relevant search results.

Based on what I see when I remove the panel cover it looks like the two hots(single phase 120v/240v) are connected to a double pole breaker. It isn't a typical setup with a main breaker above the bus bar and two hots connected to the lugs above it.

The two hot service conductors are 4 AWG, there is another 4 AWG that is tightened to a lug above the bus bar A and goes behind some breakers and I can't see the other end. There also is a sticker inside the panel stating it doesn't use a neutral, which seems odd because it has a neutral bar with the service neutral in it along with all the branch circuits neutrals as well.

So based on my limited description does anyone have an idea of what exactly is the reasoning behind this type of panel design and how it works?

I mean I can understand that the two hots going to the double pole breaker basically function as a Main Breaker. But I don't understand why there is another 4 AWG which almost seems like its a jumper between the two bus bars. I also don't understand what the previously mentioned sticker about no neutral is referring to. I will take a picture later if need be.

 

·
Super Moderator
Joined
·
21,917 Posts
A pic would be good. The wire in the middle is the neutral that runs behind the buss itself. The others are hot conductors. If the panel states 240/120 then it has a neutral.
 

·
Registered
Joined
·
49 Posts
Discussion Starter #4 (Edited)



From the pics you can see that there are wires in the main lugs that go behind the breakers. And the two Hot service entrance conductors go to a double pole breaker. I want to know what those other 4 gauge wires are going to and why the panel is set up like this.
 

·
corn-fused
Joined
·
4,769 Posts
maybe those wires from the lugs are feeding another panel?
 

·
HTTR
Joined
·
528 Posts
see how the wires on the lugs are all jacked up? they used to go on that 2 pole 60. That's the lighting main breaker, it feeds the bottom half of the panel

look at that label on the side under the yellow wirenut
 

·
Registered
Joined
·
49 Posts
Discussion Starter #13 (Edited)
Okay so I think I get it now. It used to be so the SE cable fed the top two buses and then that double pole fed the bottom bus.

But now it is wired so that the 60 AMP double pole truly acts as a Main breaker because the SE cable's ungrounded conductors are connected to it, feeding the top bus which then has jumper wires connected to the top bus feeding the bottom bus. But those jumper wires are downstream from the 60 Amp breaker so if it is off the bottom bus is off as well.

Does that sound right?
 

·
Super Moderator
Joined
·
21,917 Posts
Definitely a split buss. You are allowed 6 handles to disconnect the building. The top of the panel has room for 6 dp one of which feeds the bottom half of the panel
 
  • Like
Reactions: badreligion9265

·
Registered
Joined
·
49 Posts
Discussion Starter #15
Thanks for the pictures and explanations guys! So based off the confirmation of this being a split-bus panel is what I wrote in my last post correct about the 60Amp double-pole now acting as a main by cutting power to both top and bottom buses?
 

·
HTTR
Joined
·
528 Posts
Thanks for the pictures and explanations guys! So based off the confirmation of this being a split-bus panel is what I wrote in my last post correct about the 60Amp double-pole now acting as a main by cutting power to both top and bottom buses?
yep, and you got two neutrals under one screw in a couple spots, just tear it all out and start over
 

·
Banned
Joined
·
39,722 Posts
It looks that way, but it wasn't designed for that. Those top lugs should be fed

Someone 'effed it up ....

~CS~
 

·
Registered
Joined
·
49 Posts
Discussion Starter #20 (Edited)
no one really understands what Chicken is saying
lol well his picture certainly helped alot of what I didn't understand.

Ya I don't understand why this panel wasn't replaced because during hurricane Sandy the weather-head was knocked off the house and that along with the meter-pan got replaced. Would seem like a good time to replace the panel as well but for whatever reason it wasn't. Landlord supplied the electrician so I guess probably just a money factor.
 
1 - 20 of 21 Posts
Top