Question on raceways

Status
Not open for further replies.
S

sprky349

Member
Location
Hialeah, FL
I know that this is not allowed but not sure where to find it in the code, please help. Can you reduce a raceway from 1" to 3/4' between boxes on RMC by installing a reducing bushing in a threaded coupling? A coworker has done this a few times on the job and I tried to explain to him that its not allowed and his reply was "show it to me in the code and I wont do it again". I looked some in the book but ran out of time and was hopping that someone here knows this right off and wouldn't mind saving me some time. Thanks in advance for your help
 
ActionDave said:
There is no rule against it.

What is his reason for doing it?
Click to expand...

Thats a very good question and the same one I asked him, he just said he wanted to change it so that was the way he always did it, sounded lame to me, so I guess I will not reply to his argument and let him think he is right. Thanks for the replies
 
sprky349 said:
I know that this is not allowed but not sure where to find it in the code, please help. Can you reduce a raceway from 1" to 3/4' between boxes on RMC by installing a reducing bushing in a threaded coupling? A coworker has done this a few times on the job and I tried to explain to him that its not allowed and his reply was "show it to me in the code and I wont do it again". I looked some in the book but ran out of time and was hopping that someone here knows this right off and wouldn't mind saving me some time. Thanks in advance for your help
Click to expand...

There is a fitting called an enlarger, that does the reverse of a reducing bushing. It might be applicable in your application.
​http://www.garvinindustries.com/con...-conduit-fittings/enlarger-reducer-couplings/

The only reason why I could think it might not be allowed, is that when you mix straight male threads with straight female threads, you loose your waterproofing and possibly your official EGC continuity. With any luck, you can find product listing information that specifically allows what you intend to do. Not an easy thing to find.

Standard RMC couplings have straight female threads. RMC straight sections and nipples have tapered male threads. The taper-in-straight combination establishes your waterproofing and electrical continuity, in electrical applications. Plumbing applications often require taper for both the male and female pieces. This is why you aren't allowed to use running threads with couplings.

Look at the specs on the reducing bushing, and if you see NPT, that means it is tapered and can be used in a coupling no problem.

One thing you do want to be aware of, is that some reducing bushings are for dry locations only.
 
Welcome to the Forum!


Well, bends have to be made so as to not reduce the diameter of the conduit, tho it isnt a bend. You might could argue 344.46, or wire fill.

If this is not a code violation, and aside from impracticality,what's to keep someone from going from 4" to 1/2" RMC in the same manner?

Why not just run 1" to the box and 3/4" on, instead of changing mid-run? It could be a pita to pull wire from 1" to 3/4",unless you vac'd a string thru. Imagine fishing it, and the head slaps that reducing bushing.

Seems lame to me as well.
 
JFletcher said:
Well, bends have to be made so as to not reduce the diameter of the conduit, tho it isnt a bend. You might could argue 344.46, or wire fill.

If this is not a code violation, and aside from impracticality,what's to keep someone from going from 4" to 1/2" RMC in the same manner?

Why not just run 1" to the box and 3/4" on, instead of changing mid-run? It could be a pita to pull wire from 1" to 3/4",unless you vac'd a string thru. Imagine fishing it, and the head slaps that reducing bushing.

Seems lame to me as well.
Click to expand...
I suppose the most practical application where one might want to do this, is if the large conduit gets built in a concealed manner during the rough-in, in anticipation of "future proofing" your construction, and then you don't end up using the full capacity when you come back later. Or where you are space-constrained on landing the conduit on your equipment.

If the wire originates on the small conduit size, it should be no trouble to pull it to the larger size.

As for conduit fill, obviously the lower size would govern the full run. That is, until you enter an enclosure or conduit body with new wires.
 
Last edited:
Carultch said:
If the wire originates on the small conduit size, it should be no trouble to pull it to the larger size.
Click to expand...

Yes, but the opposite, going from larger to smaller, may present a problem. It also could trip up someone in the future who goes to add circuits based on 1" conduit, only to find it's been reduced to 3/4" mid run.
 
JFletcher said:
Yes, but the opposite, going from larger to smaller, may present a problem. It also could trip up someone in the future who goes to add circuits based on 1" conduit, only to find it's been reduced to 3/4" mid run.
Click to expand...


Agreed. It gives you a false sense of security to not have a continuous size. If you weren't allowed to adjust the size of conduits with fittings, then what would be the purpose of reducing bushings and enlargers?

Most applications of reducing fittings I've had, the reduction is immediately adjacent to an enclosure or conduit body anyway. So it isn't difficult to find or know about.
 
sprky349 said:
so I guess I will not reply to his argument and let him think he is right. Thanks for the replies
Click to expand...
Well, he is right even if he does not have a good reason for doing it.

OTOH, if I had a plethora weather proof boxes with say 1" hubs and only needed 1/2" or 3/4" raceways between them I could see using RB's for cost reasons

Roger
 
The worst thing about doing this is the potential problems for fishing in and then pulling wires. I would only allow it for specific applications on any job I was on. For example, the local Utility requires 3" PVC for their underground, but you have to reduce it to 2 1/2" at the meter can because the largest you can fit is that.
 
Status
Not open for further replies.
Top