Metallic wireway/trough Internal Taps for multiple services

Status
Not open for further replies.

Str1ve13

Member
Location
Orlando, FL
Hi,
I am an EIT and have been designing these systems for about 2 years and it came to me that I have never seen the internals of an actual trough and was wondering how the conductors coming in are actually tapped to the multiple tenants. I have searched the net for some sort of diagram but could not come up with one and was wondering if someone could give me some insight. Here's a scenario maybe to help with the explanation :smile:

3 Sets of 400kcmil conductors coming from a 3phase 208V transformer into a trough. There is a total of five tenants the trough will be feeding. Four tenants required a 100A service and One requires a 600A service. I have drawn out a diagram which can be seen here:



of what I believe could be the possible ways but again I am unsure of how the internals are worked. Any help will be very appreciated.

Thanks in advance
-Brad Pascarella
 
Str1ve13 said:
3 Sets of 400kcmil conductors coming from a 3phase 208V transformer into a trough. There is a total of five tenants the trough will be feeding. Four tenants required a 100A service and One requires a 600A service. I have drawn out a diagram... but again I am unsure of how the internals are worked. Any help will be very appreciated.Thanks in advance-Brad Pascarella

The trough "internals" will be worked (mostly) based on what gear is specified...
and sometimes it can be a real mess ;)

The actual connections will probably be done with one of several multi tap connector products. Someone will be along shortly with an image file.
 

Str1ve13

Member
Location
Orlando, FL
So does this mean each Phase; 'A', 'B', and 'C' conductors coming into the trough (three per phase in my scenario) will be connected to a "lug" above the first tenant meter then carried along to other seperate "lugs" above each of the other meters with the three conductors per phase connected between the "lugs" to carry the proper amperage, then the appropriate wiring will be tapped off the "lug" to drop down into each individual tenants service? (I hope that made sense)
 

Str1ve13

Member
Location
Orlando, FL
thx for the link augie47 I think I got it now.
One more question relating to this.

Referring to the original scenario, bringing three sets of 400kcmil, is it allowable to use 1 set of 400kcmil (rated for 335A) to service the three 100A tenants through a set of A, B, C Taps, then because of space issue of the first tap, run the other two sets of 400kcmil (rated for 770A) bypassing the first set of taps, to a seperate set of A, B, C Taps within the same trough to service one 100A and one 600A tenant?
Is there a limit on the number of actual taps a trough can hold?
 
Last edited:

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
(a) I see no problem with the distribution method you describe.
(b) There limitation based on % of fill, wire deflection and wires per
crosssectional area. You would need to look at the NEC Article
pertaining to the type wireway/gutter in use.

I might also mention, the reference I gave you showed "distribution blocks".
Such taps are often made using insulated mechanical lugs per:
http://ebusiness.ilsco.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&langId=-1&catalogId=1&categoryId=1045
 
Last edited:
Status
Not open for further replies.
Top