Ampacity of conductors in Auxiliary Gutters

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gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
For the wireway fill, there is also an exception for stage lighting and circuits - no derating no matter how many wires you put in a wireway as long as 20% fill isn't exceeded.

Granted, stage lighting usually has so many branch circuits that they probably won't ever all be used at full load at once, but it seems like another arbitrary rule.

I have one project with over 150 20A branch circuits going up to above. Those could all be in a single wireway.

Heh. You should have seen some of the light plots I designed in my community theater days. Fortunately, unless you're doing A Long Days Journey Into Night, you are never likely to have a show run long enough for the 3-hour rule to kick in.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Yes
I can think of no technical reasoning

you could have 30 #12 with 10 A each (all single ph)
or 32 with 5 A
which field is stronger? Which generates more heat?
chances are you'll have some cancellation since they are likely H/N pairs

how about 30 1/0 with 60 A vs 32 with 40 A?

no rhyme nor reason

you can also take an existing gutter and put a separator plate down the middle of it and claim it is two enclosures and thus put in twice as many conductors in the same volume.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
you can also take an existing gutter and put a separator plate down the middle of it and claim it is two enclosures and thus put in twice as many conductors in the same volume.

Very sneaky! But does that actually work? I'm not up on the rules for gutters/trays. Does the plate really turn the gutter/tray into two raceways for calculation purposes?
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
Heh. You should have seen some of the light plots I designed in my community theater days. Fortunately, unless you're doing A Long Days Journey Into Night, you are never likely to have a show run long enough for the 3-hour rule to kick in.

Or just about any Shakespeare.

You lighting guys! As a sound designer I always brought a book to tech rehearsals so I would have something to read while I was sitting in the house waiting for you guys to build your cues. :D
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Or just about any Shakespeare.

You lighting guys! As a sound designer I always brought a book to tech rehearsals so I would have something to read while I was sitting in the house waiting for you guys to build your cues. :D

I never worked with a programmable board. I had sheets with the "X" and "Y" circuits adjacent so I'd write in each scene for the preset. Worst was directors who kept changing the levels at every rehearsal. At the start of rehearsals I'd do a rough hang, and add specials as the blocking was developed and scenery was built, but I could usually get the general lighting nailed down early on. It got so bad that at one rehearsal every time the director would want the lights changed I'd wait a bit, and without moving a thing I'd say "How's that?" Five times out of ten he'd say "Looks good!" :roll:
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
I never worked with a programmable board. I had sheets with the "X" and "Y" circuits adjacent so I'd write in each scene for the preset. Worst was directors who kept changing the levels at every rehearsal. At the start of rehearsals I'd do a rough hang, and add specials as the blocking was developed and scenery was built, but I could usually get the general lighting nailed down early on. It got so bad that at one rehearsal every time the director would want the lights changed I'd wait a bit, and without moving a thing I'd say "How's that?" Five times out of ten he'd say "Looks good!" :roll:

I once worked with a director once on a production of Hamlet where he wanted 37 distinctively different thunder sound cues. I reused a couple of them, thinking with all the rest of what was going on on stage, he'd never know. I was wrong. :D

There were two types of directors I really disliked working with.

There were the ones who gave me such specific instructions that I had great difficulties satisfying them with the sound effects recordings I could find. This got better with the advent of the internet and DAW software (ProTools).

And then there were the ones who didn't really know what they wanted and gave me virtually no instructions; they would just tell me what they didn't like after I put a design together, which often was pretty much my whole design.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Very sneaky! But does that actually work? I'm not up on the rules for gutters/trays. Does the plate really turn the gutter/tray into two raceways for calculation purposes?

In my opinion it does. However your mileage may vary. There have been threads that debate this, with no general consensus.


There were two types of directors I really disliked working with.

There were the ones who gave me such specific instructions that I had great difficulties satisfying them with the sound effects recordings I could find. This got better with the advent of the internet and DAW software (ProTools).

And then there were the ones who didn't really know what they wanted and gave me virtually no instructions; they would just tell me what they didn't like after I put a design together, which often was pretty much my whole design.

I'm sure most of the contractor's could say something very similar about us engineers and the projects we design. :)
 
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