How many EMT can I fit?

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MacG

Member
I am an audiovisual consultant :roll: , and I am aware that I can over populate a nema screw cover terminal can with too many conduits (or gang boxes for that matter. We typically use 3/4 conduit through 2". If I have (2) 1.5" emt fittings landing on a terminal box what is the minimum spacing between the punches that will need to be done?

Additionally, is there a chart that shows the centerline distances between various connectors EG .75" to 1.5"? I found one for minimum conduit spacing but not sure if that is for connectors or conduit runs. For example it shows for (2) 1.25" conduits there needs to be 2.5" spacing between them. This seems enough for connectors too but that's why I am asking.

Another thing that is unclear for me is what is the maximum size conduit that can be punched for a 2.5" deep box like a RACO 942?

Thanks for your efforts on my behalf,

MacG
 

iwire

Moderator
Staff member
Location
Massachusetts
If I have (2) 1.5" emt fittings landing on a terminal box what is the minimum spacing between the punches that will need to be done?

Additionally, is there a chart that shows the centerline distances between various connectors EG .75" to 1.5"? I found one for minimum conduit spacing but not sure if that is for connectors or conduit runs. For example it shows for (2) 1.25" conduits there needs to be 2.5" spacing between them. This seems enough for connectors too but that's why I am asking.

Another thing that is unclear for me is what is the maximum size conduit that can be punched for a 2.5" deep box like a RACO 942?
This may help some, they give spacing that will allow for locknut spacing.

http://www.powerstrut.com/psjan2005/fibergl183.jpg

keep in mind with most set screw EMT connectors if you have space for the lock nut the connectors will fit.

But if your using compression EMT connectors the spacing will be wider to allow for the larger connector.

You could go to the manufactures web sites and probably download fitting dimensional data as well.
 

MacG

Member
Welcome to the Forum. Punch your knockouts where they work for you.

Might want to ask these guys for more insight.
Thanks for the link. I am not cutting in the KO's. If I had all of the fittings and tools I would do that just so I'd know f it's work which is why I asked about spacings of KO's. I am only doing things on paper and using terms like "sized by electrical" only to find out that you can't put a 1.5" conduit in a switch box :) (really, it's not THAT bad). So I came here to make a few electricians life easier when it comes to my design intent.

Thanks again,

MacG
 

MacG

Member
This may help some, they give spacing that will allow for locknut spacing.

http://www.powerstrut.com/psjan2005/fibergl183.jpg

keep in mind with most set screw EMT connectors if you have space for the lock nut the connectors will fit.

But if your using compression EMT connectors the spacing will be wider to allow for the larger connector.

You could go to the manufactures web sites and probably download fitting dimensional data as well.
Thanks for the reply. I had found a similar chart but there was no reference to the lock nut spacing so this was helpful to compare.

I know that there is a rule or two about cubic inches and the number of conductors in a box but I think that is not so much about low voltage.

I do not know if there was any area percentage rule like conduit fill related to how much surface area of given face of a box could be punched for fittings.

Thanks again for you reply,

MacG
 

benaround

Senior Member
Location
Arizona
Mac,

For a few dollars you could go buy the parts that you spec. and all your questions will be

answered. You could even spec. the same parts !!
 

MacG

Member
Nice link, is that a legit site?



Mac, look at Arts. 725.3, 800.3 and 820.3 and tell me how the NEC applies to your install?
Chris,

If I understand your question, we have low voltage cabling in plenum spaces, in conduit, cable trays, etc. That include not only audio and video signal cables but control cables and occasionally fire/life.

The code book link is handy for me because we also spec technical power panels in or bid/constructions docs. I have had to explain in the field how to isolate the AV equipment racks from the building ground and how to bond the rack to the technical power isolated ground instead. It would have been helpful to have the NEC references at that time.

Thanks,

MacG
 

MacG

Member
Mac,

For a few dollars you could go buy the parts that you spec. and all your questions will be

answered. You could even spec. the same parts !!
True enough but since you've benaround you would know that just because noob behind a desk can cram it in does not mean it should be done. I am trying to ease some of those it works on paper things. Like when one line on a drawing represents (2) 2" (6) 4" and (6) 1.5" passing through a concrete beam and the Architect misses it in coordination.

Thanks,

MacG
 
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