Sizing a Wire Trough Correctly?

[Smart $]

The actual solution complies with NEC if we intend to use only one circuit breaker of 1200 A.
It will be 16 cables of 350 mcm all along the trough,
there will be 16 uni taps and 128 connectors [8 per unitap] of 350 MCM and other of 3/0.
If we use [for now] 2 breakers of 400 A respective 200 A and for the future extension we will keep only 2 places for two 600 A breakers no need for any connectors and all the cable could be 3/0-as Smart$ said. The trough has to accommodate 8*4 [or 10*4] 3/0 cables only. In any case minimum 30?*10? in actual solution and 20?*6? in the last solution will be the trough dimensions.

WOW! Those dimensions are HUGE.

The method I proposed would be 13 #3/0 for current panels. Allow for an additional future 16. Total now and future 29 #3/0.

I'd figure CSA for that but at work and don't have ready access to wire data. Someone care to do the math for me...???

 

[RUWired]

29 x .2679 (3/0)= 7.7691sq"

 

[Smart $]

29 x .2679 (3/0)= 7.7691sq"

So if max fill is 75%, need just over 10in?. A 4?4 should cover the extra area required for tapping the #3/0 EGC.

 

[RUWired]

Wire way fill is 20%, an 8x8 @ 20% is 12.8Sq".

 

[Smart $]

Wire way fill is 20%, an 8x8 @ 20% is 12.8Sq".

True of wireway... but not auxiliary guuter, which permits 75% fill.

The basic, if not only Code distinction between an auxiliary gutter and a wireway is a gutter is...

...used to supplement wiring spaces at meter centers, distribution centers, switchgear, switchboards, and similar points of wiring systems.

Non-metallic wireway is required to be listed, whereas non-metallic auxiliary gutter is only required to be listed for conditions of use.

So is there something outside or beyond Code which dictates whether the enclosure is an auxiliary gutter or wireway, aside from the quoted passage above?

FWIW, UL 870 covers both.

IMO, if this enclosure is connected directly to switchgear or similar distribution equipment, it is a gutter. If all conductor entries utilize another Chapter 3 wiring method, it is a wireway...

 

[RUWired]

True of wireway... but not auxiliary guuter, which permits 75% fill.

...

Same for auxiliary gutters, see 366.22. You proposed no splices. 75% fill is only cross section areas where gutters contain splices.

 

[Smart $]

Same for auxiliary gutters, see 366.22. You proposed no splices. 75% fill is only cross section areas where gutters contain splices.

You are correct. 8x8 it is.

 

[RUWired]

The 12 x 12 wireway will work IMO, it meets all the rules I can see. I would make sure the top tap block meets the 312.6(A) and (B) dimensions going into the raceways going out the top of the wireway/gutter.

 

[kwired]

"The other problem you might run into is that any panel(s) front edge can't
be beyond a gutter or wireway front edge, as well as disconnects!
So there will be no reach over... sorry couldn't find this article on short notice. "

NO, NO PROBLEM at all because I know how to use strut to build the panel out to the front of the trough...also no one seems to be helping me with my question, without the size of the trough how can you be sure the panel will extend past the face of the wireway/gutter/whatchamacallit? lol #sarcasm


ANYWAYS, back to the original question. Who wants to show the proper math and the size gutter/wireway per the NEC?

It has been pointed out you have a 6 inch variance that is acceptable. If you have a gutter or wireway that has to be 12 inches deep it is not likely all contained conductors end up feeding an enclosure that is only 4 inches deep, but you could still have a large gutter/wireway supplying smaller sized enclosures. You need to do the calculating before you order components and/or before you start slapping them on a wall. If you have a 12 inch gutter below a 4 inch deep panelboard you probably want to space the panelboard from the mounting surface by at least 2 inches somehow.

Proper math - total cross section x.20 = max conductor fill.

Total cross section x .75 = max fill at any cross section that includes conductors and splicing/tapping devices located within that cross section. This may mean you need to stagger splices and taps so they are not all in the same cross sectional area, or will need an even bigger wireway/gutter.

 

[dkidd]

So is there something outside or beyond Code which dictates whether the enclosure is an auxiliary gutter or wireway, aside from the quoted passage above?

The 2011 Handbook says:

As its name implies, an auxiliary gutter provides additional gutter space for wiring in various types of electrical enclosures and equipment. This additional gutter space may be necessary to provide sufficient room for the number of conductors in an enclosure or to provide adequate wiring bending/deflection space where conductors connect to a terminal. Although the construction of an auxiliary gutter is no different from that of a wireway, it is the field application of this equipment that differentiates an auxiliary gutter from a wireway.
A wireway is a raceway in accordance with the definition of raceway in Article 100. Auxiliary gutters supplement enclosure wiring spaces and are not encompassed by the definition of raceway. Therefore, Code requirements that apply only to raceways do not apply to auxiliary gutters. An example of such a requirement is 230.7, which prohibits service conductors from being installed in a raceway with conductors that are not service conductors. This rule applies to wireways installed in accordance with Article 376 and 378. However, an auxiliary gutter installed to supplement the wiring space of a service equipment enclosure is not a wireway and therefore is not subject to 230.7.

If it connects with nipples, it's a wireway.

 

[Smart $]

The 2011 Handbook says:

...

If it connects with nipples, it's a wireway.

Goes with my assessment...

... IMO, if this enclosure is connected directly to switchgear or similar distribution equipment, it is a gutter. If all conductor entries utilize another Chapter 3 wiring method, it is a wireway...

While the diagram presented by the OP shows the trough abutting the SDM, it does not rule out using close nipples. For it to be an auxiliary gutter, one would use a flanged transition piece at the left end and the entire cross sectional area of the gutter would be cut out of the SDM's side.

 

[GoldDigger]

So if you cut out the entire bottom panel of the enclosure and a matching hole in the side of a section of wireway you now have an auxiliary gutter instead?

Tapatalk!

 

[Smart $]

So if you cut out the entire bottom panel of the enclosure and a matching hole in the side of a section of wireway you now have an auxiliary gutter instead?

IMO, yes.

I had the impression that Code at one time limited the length of the gutter to 30' from the equipment it is a gutter to. Anyone know if that's still true, or when it was removed, or if I'm just outright mistaken???

 

[RUWired]

IMO, yes.

I had the impression that Code at one time limited the length of the gutter to 30' from the equipment it is a gutter to. Anyone know if that's still true, or when it was removed, or if I'm just outright mistaken???

Still true, see 366.12(2)

 

[iwire]

Goes with my assessment...

​

While the diagram presented by the OP shows the trough abutting the SDM, it does not rule out using close nipples. For it to be an auxiliary gutter, one would use a flanged transition piece at the left end and the entire cross sectional area of the gutter would be cut out of the SDM's side.

If the listing of the equipment used indicates 'wireway' I can't see how it becomes an auxiliary gutter by virtue of how it is installed.

 

[Smart $]

If the listing of the equipment used indicates 'wireway' I can't see how it becomes an auxiliary gutter by virtue of how it is installed.

It's not just my opinion...

The 2011 Handbook says:

As its name implies, an auxiliary gutter provides additional gutter space for wiring in various types of electrical enclosures and equipment. This additional gutter space may be necessary to provide sufficient room for the number of conductors in an enclosure or to provide adequate wiring bending/deflection space where conductors connect to a terminal. Although the construction of an auxiliary gutter is no different from that of a wireway, it is the field application of this equipment that differentiates an auxiliary gutter from a wireway.
A wireway is a raceway in accordance with the definition of raceway in Article 100. Auxiliary gutters supplement enclosure wiring spaces and are not encompassed by the definition of raceway. Therefore, Code requirements that apply only to raceways do not apply to auxiliary gutters. An example of such a requirement is 230.7, which prohibits service conductors from being installed in a raceway with conductors that are not service conductors. This rule applies to wireways installed in accordance with Article 376 and 378. However, an auxiliary gutter installed to supplement the wiring space of a service equipment enclosure is not a wireway and therefore is not subject to 230.7.

...

 

[kwired]

So if you cut out the entire bottom panel of the enclosure and a matching hole in the side of a section of wireway you now have an auxiliary gutter instead?

Tapatalk!

Wow, if that is the way it is, that means I have seldom used aux gutters. I've found it is generally much faster to use a KO punch and make the round hole even if just using a close or chase nipple then it is to make a square hole plus drilling for mounting screws. If you can only fill the gutter to 20 percent you certainly don't need a 100% hole to contain conductors that only take up 20%.

Full size gutter fittings don't adapt all that well to some enclosures either. Ever tried to use a 8x8 gutter connector in a motor starter enclosure that is only 4 inches deep?

 

[Smart $]

Wow, if that is the way it is, that means I have seldom used aux gutters. I've found it is generally much faster to use a KO punch and make the round hole even if just using a close or chase nipple then it is to make a square hole plus drilling for mounting screws. If you can only fill the gutter to 20 percent you certainly don't need a 100% hole to contain conductors that only take up 20%.

Full size gutter fittings don't adapt all that well to some enclosures either. Ever tried to use a 8x8 gutter connector in a motor starter enclosure that is only 4 inches deep?

The size and shape of the hole(s) don't matter. It's what you put in/through the holes. If you use a chase nipple or any other any nipple, it's not a gutter. It'd be a wireway... because a nipple is part of a different wiring method under Chapter 3.

 

[iwire]

It's not just my opinion...

​

I think they are nuts.

That is like saying a listed incandescent fixture becomes a Flouresent fixture when used with a CFLL.

 

[kwired]

The size and shape of the hole(s) don't matter. It's what you put in/through the holes. If you use a chase nipple or any other any nipple, it's not a gutter. It'd be a wireway... because a nipple is part of a different wiring method under Chapter 3.

Ok, say you have a wireway adapter where the wireway meets a panelboard, you then route cables through wireway and exit via conventional "raceways" like RMC or EMT. since you entered with a different wiring method it is not a wireway but rather an aux gutter?

I'm sorry but I really don't see that being enough to call it a different name, there has to be more to it then that.