Interesting Picture Of A Breaker Panel - Angles Matter

[Marilyn Manson]

At first glance, one might think there are spare breakers at the bottom of each side.

Angles matter. ;-)

[Jim Joyce]

That's nice work. Most panels that I've seen are way more sloppy.

[hubops]

Wonder what the top-outside looks like ? Do all the circuits exit through 1 large hole ? John T.

[Marilyn Manson]

I don't know. I just grabbed that picture from Google images.

I was going to email it to a first time homeowner and then use it to explain - via phone - what happens behind the front cover. 120V circuits, 240V, wire colors, bus bars, etc.

Then I noticed that the wires don't visually line up with their respective breakers and decided that this might not be the best picture to use. It would probably be more confusing than helpful to someone who has never seen the inside of a breaker panel.

[gfretwell]

Nobody ever accused you of understanding perspective. ;-)

[gfretwell]

I was wondering that myself. Sometimes "neatness" comes with derating issues.

[Marilyn Manson]

That why I said "at first glance". ;-)

Bottom line: It's not a great picture to use to explain how a panel is wired. You'd first have to "verbally" fix the "visible" by telling the student to mentally shift all the wires down one, maybe 2 breakers.

Nah, that won't confuse matters much. ;-)

I think I'll look for a better picture.

[Scott Lurndal]

I suspect it's because there is a raceway above the panelbox and everything is run in conduit to that raceway, then through a large KO to the panelbox.

[gfretwell]

If the combined length between where the installer started tywrapping those conductors and the top of the chimney coming out of the box is

24" or more the wires need to be derated. They ain't gonna make it.

There are also a lot of inspectors that simply reject that chimney coming out of a panelboard if it terminates above the top plate because a fire in the panelboard enclosure could be propagated into the second floor or attic. For the last several cycles any bundle of romex going through insulation/draft stop needs to be derated too. Note there is no minimum length given. Sometimes "neatness" can get you a tag.

334.80 ... Where more than two NM cables containing two or more current-carrying conductors are installed, without maintaining spacing between the cables, through the same opening in wood framing that is to be sealed with thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(3)(a) and the provisions of 310.15(A)(2), Exception, shall not apply