Required Pull-Box size for conduit entry into side of equipment

[philly]

I have a piece of equipment that I will be routing conduit down a wall and into the side of the equipment. The piece of equipment is located only 8" from the wall so there is not much room for turning conduits coming down the wall into the side of the equipment. Instead of using an LB or conduit fitting for turning the conduits into the equipment I've decided to use a pull-box between the equipment and the wall.

I have (4) 2.5" conduits coming down the wall with each conduit containing parallel sets of 4/0 conductors. I am going to attached the conduits to the top of my pull-box and used the box to turn the cables into the side of the equipment which the box is attached to.

My question is what specific dimensions the box needs to be. There is only 8" between the equipment and wall so hopefully this 8" is enough horizontal lenghts to turn cables. How about the vertical length or height of this box? Are there any requirements for the box height?

 

[augie47]

If I understand correctly, with the 8" limiting factor there is no way to use a box directly and meet Art 312 requirements.
My first thought would be to mount a pull box approximately 16" x 28"on the wall, and convert to flex into the machine (figuring straight thru pull)

 

[philly]

If I understand correctly, with the 8" limiting factor there is no way to use a box directly and meet Art 312 requirements.
My first thought would be to mount a pull box approximately 16" x 28"on the wall, and convert to flex into the machine (figuring straight thru pull)

Yes 8" is the limiting factor between machine and wall. Are you saying that you could mount a 16" long x 28" high (8" depth) on the wall and then out the bottom of the bux use flex to connect into the machine?

Would it be better to just use flex from the RMC into the machine instead of having the pull box, or is the pull-box needed for code requiremnts?

 

[augie47]

I would say you go do either. Keep in mind the flex at that size/current can not be a grounding means so you need an equipment grounding conductor.
Whether you pull to a box or directly into the equipment is probably a judgment call as to the ease of routing direct.

I think your question poses an interesting situation. I had not given it thought over the years but I assume a listed piece of equipment does not need to meet Art 312 requirements (I've pulled into a lot that don't)

(as a side note: does your equipment have the required disconnect or are you needing one externally)

 

[philly]

I would say you go do either. Keep in mind the flex at that size/current can not be a grounding means so you need an equipment grounding conductor.
Whether you pull to a box or directly into the equipment is probably a judgment call as to the ease of routing direct.

I think your question poses an interesting situation. I had not given it thought over the years but I assume a listed piece of equipment does not need to meet Art 312 requirements (I've pulled into a lot that don't)

(as a side note: does your equipment have the required disconnect or are you needing one externally)

The piece of equipment is actually an inverter and there is no disconnect needed.

I was under the impression that because this was attaching to a piece of equipment as you mentioned this would not need to meet the requirements of article 312?

Were you saying above that you can use flex directly from the RMC to the equipment? Will the 8" space allow adequate room for this?

 

[augie47]

I see no problem with transitioning from RMC to flex into your equipment (keeping 250.118 in mind) IF the 8" gives you room to bend the flex. With 2-1/2", I'm unsure.
(You can always use a flex 90, but those are such a "bear" with larger wire)

 

[maghazadeh]

Philly,
I do not know your axact situation and dimentions for the equipment and accessability to termination point to the equipment in question. As you mentioned you are going to run
(4) 2.5" RMC.
1) If you are not exceeding 360 deg. bends on your conduit run, then you do not need a
pull box, and you can go from RGC to flex with a straight connector and flex to
equipment with a 90 deg. connector. however for that many conduit and sizes of wires
installing a pull box will make the job much easier.
2) 2.5" RGC the O.D. is more like 3", so 3" X 4 = 12" assuming 1" space between conduits
and edges of pull box = 5", so minimum 17" wide box needed where conduits come into
pull box from the top. I would use 24" wide.
3) You need to decide if your conduit entry/exit will be a angle pull or straight pull.
For straight pull, (2.5" X 8)+(2.5" X 3)=20" + 7.5"=27.5" min. needed.
Hope this will help and good luck.

 

[cadpoint]

I agree with post 7 and Augie too. It's not so much the 8" as much as getting to what the workable space given at the gear.

They also make Flex 90's.

 

[kwired]

It may be out of the question but can you run down the other side of the wall and either LB or pull box there and then go through the wall and into the back of your equipment? Sounds easier if it is acceptable to do so.

 

[philly]

Philly,
I do not know your axact situation and dimentions for the equipment and accessability to termination point to the equipment in question. As you mentioned you are going to run
(4) 2.5" RMC.
1) If you are not exceeding 360 deg. bends on your conduit run, then you do not need a
pull box, and you can go from RGC to flex with a straight connector and flex to
equipment with a 90 deg. connector. however for that many conduit and sizes of wires
installing a pull box will make the job much easier.
2) 2.5" RGC the O.D. is more like 3", so 3" X 4 = 12" assuming 1" space between conduits
and edges of pull box = 5", so minimum 17" wide box needed where conduits come into
pull box from the top. I would use 24" wide.
3) You need to decide if your conduit entry/exit will be a angle pull or straight pull.
For straight pull, (2.5" X 8)+(2.5" X 3)=20" + 7.5"=27.5" min. needed.
Hope this will help and good luck.

I'm a little confused at what your suggesting here. Are you suggesting brining the (4) 2.5" conduits down into the top of a pull box which is 24" wide, 27.5" high and 8" deep (limited by wall space). Then coming out of the bottom of the pull box are you suggesting that I flex between the bottom of the pull box to the side of the enclosure? Will having this pull box in-between be easier than just connecting flex to the RMC? I'm curious why b/c I dont have much experience with this.

It sounded like if it is workable you are saying that we can just use flex directly between the conduit and the equipment? You mentioned using a straight piece and a 90? Why not just use a 90 piece?

 

[maghazadeh]

I'm a little confused at what your suggesting here. Are you suggesting brining the (4) 2.5" conduits down into the top of a pull box which is 24" wide, 27.5" high and 8" deep (limited by wall space). Then coming out of the bottom of the pull box are you suggesting that I flex between the bottom of the pull box to the side of the enclosure? Will having this pull box in-between be easier than just connecting flex to the RMC? I'm curious why b/c I dont have much experience with this.

It sounded like if it is workable you are saying that we can just use flex directly between the conduit and the equipment? You mentioned using a straight piece and a 90? Why not just use a 90 piece?

Location of pull box should be next to the equipment and not directly in between wall and equipment. What do you mean, "why not just use a 90 piece"? If you mean to go down with RGC's and then use LBs. 8" space is not enough room for attaching LBs to the machine with hard conduit and pulling/rerouting wires through LBs.
Are you sure the equipment enclosure does not have a vertical wireway to allow for top feed?
By the size and number of wires you stated I assume it is rated at least 280 KVA at 208V, so most equipment that size should give option for top, side, and bottom feed.

 

[maghazadeh]

I'm a little confused at what your suggesting here. Are you suggesting brining the (4) 2.5" conduits down into the top of a pull box which is 24" wide, 27.5" high and 8" deep (limited by wall space). Then coming out of the bottom of the pull box are you suggesting that I flex between the bottom of the pull box to the side of the enclosure? Will having this pull box in-between be easier than just connecting flex to the RMC? I'm curious why b/c I dont have much experience with this.

It sounded like if it is workable you are saying that we can just use flex directly between the conduit and the equipment? You mentioned using a straight piece and a 90? Why not just use a 90 piece?

Location of pull box should be next to the equipment and not directly in between wall and equipment. What do you mean, "why not just use a 90 piece"? If you mean to go down with RGC's and then use LBs. 8" space is not enough room for attaching LBs to the machine with hard conduit and pulling/rerouting wires through LBs.

Are you sure the equipment enclosure does not have a vertical wireway to allow for top feed?
By the size and number of wires you stated I assume it is rated at least 280 KVA at 208V, so most equipment that size should give option for top, side, and bottom feed.

Regarding box size the 27.5" high is minimum and next standard box size is 24" X 30" or 24" X 36".

 

[iMuse97]

Location of pull box should be next to the equipment and not directly in between wall and equipment. What do you mean, "why not just use a 90 piece"? If you mean to go down with RGC's and then use LBs. 8" space is not enough room for attaching LBs to the machine with hard conduit and pulling/rerouting wires through LBs.

Are you sure the equipment enclosure does not have a vertical wireway to allow for top feed?
By the size and number of wires you stated I assume it is rated at least 280 KVA at 208V, so most equipment that size should give option for top, side, and bottom feed.

Regarding box size the 27.5" high is minimum and next standard box size is 24" X 30" or 24" X 36".

I would use sealtite to make the final connection. Helps to eliminate vibration transmission into pipe. Here's a sealtite 90deg. fitting. They also make 45deg. and even 30 deg.http://www.foxelectricsupply.com/co...tail.asp?qsCatID=25012&qsProductNo=ARLLT90200

 

[philly]

Location of pull box should be next to the equipment and not directly in between wall and equipment. What do you mean, "why not just use a 90 piece"? If you mean to go down with RGC's and then use LBs. 8" space is not enough room for attaching LBs to the machine with hard conduit and pulling/rerouting wires through LBs.

Are you sure the equipment enclosure does not have a vertical wireway to allow for top feed?
By the size and number of wires you stated I assume it is rated at least 280 KVA at 208V, so most equipment that size should give option for top, side, and bottom feed.

Regarding box size the 27.5" high is minimum and next standard box size is 24" X 30" or 24" X 36".

Unfortunately the equipment does not provide for top entry.

The piece of equipment sits in the corner of a room with its back against the wall and the 8" space between the equipment and the side wall.

Are you saying to locate the box on the wall out in front of the equipment somewhere instead of directly next to it in the 8" space? If so are you then saying to use flex to connect from the box to the equipment? I guess I'm struggling to understand how a box would make things any easier as opposed to just connecting flex directly to the RMC coming down the wall.

With the flex piece should we use a straight piece of flex with 90deg fittings or a 90deg piece of flex?

Thanks for the help.

 

[philly]

I think your question poses an interesting situation. I had not given it thought over the years but I assume a listed piece of equipment does not need to meet Art 312 requirements (I've pulled into a lot that don't)

What listing are you referring to? A UL listing? If so then this equipment is UL listed. In this case could we just get away with a box mounted on the side?

 

[augie47]

My comment about the equipment was directed to the fact that often times it seems listed equipment does not provide the same "pulling" dimmensions that the NEC requires,,,and they are not required to do so.
I mention that only to say that you might want a pull box to make the pull easier. If your run meets the NEC rerquirements as far as # of bends, etc. and you preceive no problem in pulling directly into the equipmemt, the flex direct to the conduit is certainly acceptable.

 

[maghazadeh]

Are you saying to locate the box on the wall out in front of the equipment somewhere instead of directly next to it in the 8" space?

Yes, because your pull box should be installed in a maner that you can have access to it in the future.
If you install the box right between the wall and the equipment then how would you remove and put back the cover.

 

[maghazadeh]

With the flex piece should we use a straight piece of flex with 90deg fittings or a 90deg piece of flex?

Straight piece of flex with 90 deg. fittings with wires pulled all the way through the 90 deg. flex fittings. Then bring the equipment as close as possible with enough room for you to push the wires through the K.O.s tighten all your fittings to the equip. enclosure, then push the equip. to about 8" desire distance to the wall. after that you can proceed to anchor the unit to the floor. This way you will have flexability to move flex 90 fittings up, down, side to side to match where your K.O.s are.
For a 90 deg. piece of flex you will need at least 16" -to- 20" room from wall to the unit enclosure in order to attach flex to enclosure properly.
If you can post a picture of the unit and dimensions that could help everyone here to visualize it better.

 

[augie47]

According to this chart:
http://www.semiconduits.com/yf_703.html
2-1/2 Flex would take 7.5" of space.
Considering the connector, you would be better off with a 45? connector, IMO.
(With larger conductors I hate wrestling with 90? connectors)

 

[philly]

I've decided to go with flexible conduit between the RMC and the enclosure

I am a bit confused on weather I need to use a stright piece of flex with a 90deg flex fitting or weather I need to use a 90deg (or 45deg) piece of flex with the 90deg (or 45deg) fitting. Or are others stating that you can simply use a stright pice of flex and bend it into to side of the enclosure without any type of fitting?