Supporting Pull Boxes on Raceways

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vidividi12

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San Marino
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Electrician
Hi,

In our specs, it is mentioned that "support boxes and conduit above ceiling independently."In my opinion, this item is for prohibiting to mount raceways on suspended ceiling.
We have installed our raceways with trapeze type supports as shown below. However, our manager wants to add one supporting rod from every pull boxes to the concrete ceiling.

Most of our boxes are 10x10x5cm dimensions pull boxes. They are like 2-gang device boxes. I found an item below in NEC 314.23.

Can this item be used for powering my arguments or shall we install a rod for every boxes?

314.23

(E) Raceway Supported Enclosure, Without Devices, Luminaires, or Lampholders. An enclosure that does not contain a device(s) other than splicing devices or support a luminaire(s), lampholder, or other equipment and is supported by entering raceways shall not exceed 1650 cm3 (100 in.3) in size. It shall have threaded entries or have hubs identified for the purpose. It shall be supported by two or more conduits threaded wrenchtight into the enclosure or hubs. Each conduit shall be secured within 900 mm (3 ft) of the enclosure, or within 450 mm (18 in.) of the enclosure if all conduit entries are on the same side.
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The code does not permit the box to be supported using threaded conduit and locknuts. The box must have threaded hubs if you want to use the conduit as the required support for the box.
 
Thank you very much for your reply. I just ask to learn this subject. Our boxes are so small and 500cm3 (10x10x5cm) in size. This is under 1650cm3. In these cases, should a rod be added?
 
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vidividi12 said:
Thank you very much for your reply. I just ask to learn this subject. Our boxes are so small and 500cm3 (10x10x5cm) in size. This is under 1650cm3. In these cases, should a rod be added?
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Can be any method of support, but that box must not be supported by raceway only unless it has integral hubs as mentioned.
 
It does seem strange that you can install all the C fittings or LBs with EMT and they don't have to be supported but boxes do. Guess it's the locknut they don't like. Maybe they should make boxes with integral fittings
 
Eddie702 said:
It does seem strange that you can install all the C fittings or LBs with EMT and they don't have to be supported but boxes do. Guess it's the locknut they don't like. Maybe they should make boxes with integral fittings
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They do make cast boxes with threaded hubs, but they are expensive and not practical for that your application.
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Sparks4All said:
Pulling C's do not need to be supported.
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But the raceways entering them do need supported usually within 3 feet. Conduit bodies and boxes with hubs like those pictured in post 7 follow the same rules on support.

Typical bell box hubs are not allowed to support the box by the raceway.

You must (normally) have at least two raceways supporting the conduit body or box also.
 
We don't support condulet's in the same manner of junction or pull boxes. Junction or pull boxes are not designed to be part of a conduit raceway system and need to be supported to prevent bowing or sagging.

Cast boxes with threaded hubs are not condulets, they are junction boxes.
 
jeremy.zinkofsky said:
We don't support condulet's in the same manner of junction or pull boxes. Junction or pull boxes are not designed to be part of a conduit raceway system and need to be supported to prevent bowing or sagging.

Cast boxes with threaded hubs are not condulets, they are junction boxes.
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Read 314.23 plus subparts (E) and (F) carefully, both conduit bodies and cast boxes with threaded hubs are primarily what it is addressing in E and F.
that 100 cubic inches mentioned in there is the main difference between E and F support requirements and larger pull and junction boxes, the hubs is the main difference between E and F support requirements and other smaller device type boxes.
 
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