ECN Forum Forums General Topics of the Trade General Discussion Area Gutter box for NM installs.

Only the wires in the gutter will be derated. Do you own a codebook? I am required to have one for my classes.

I do, but it makes it a tad easier to interpret by asking the question, rather than assume it to be one way, only to be wrong.

I use gutters like this a lot! And yep <30 conductors at any cross section. If I have a lot of room to work with, I'll take a 6' and put it above or below the panel, with about 2' either side, so I dont have to figure out how to squeeze all the romex, or MC into one stud bay. This work fantastic for MM w/ dist 200a panels with a 3" concentric, and a few halfs at the bottom. Otherwise how would they all fit in there? This way you leave all the grounds in the gutter. (I like cans too)

I put a ground bar, and bond with a #6, only 'cause I never use #8, and have tons of 6 on the truck.

Anyway, while on the subject of derating, and using fewr KO's...

I have seen alot of this done lately.

42 circ panel with 4 1" emt's to cans and gutters (like 50' away) with the whole panel going through it all in #10's, all derated. Late one I saw, I did the math, and it was all pretty close... I don't like it, but seems to be a growing trend with a few companies around here. I guess it saves some mat's and labor on bending a few more conduits, but just don't feel right?

When we last had a discussion on this topic, I had the following idea:

A large shallow gutter, perhaps 1" thick, 2 feet tall, as wide as necessary. Spaced through the inside on perhaps 2" centers would be insulating stand-offs.

The kicker would be that every 'bay' (horizontal or vertical channel defined by the stand-off array) would be tested and _listed_ to carry a certain number of conductors _without derating_. You would have a large grid, and could run wires as needed to get from the breaker panel to the appropriate conduit, and as long as you kept to fewer than X conductors per bay, you would be in the clear. So rather than being limited to 30 conductors across the entire cross section, you might be limited to 20 conductors per bay, but have space for 240 conductors in the 8 horizontal bays.

I have not worked out the physics of how many runs would actually be reasonable in a 'bay'.

-Jon