Can a non-metallic electrical box be considered a "cast FD box"?

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Charlypt

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Location
Florida
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Electrician
Can a non-metallic electrical box be considered a "cast FD box", according to the language?
A FD box can be non-metallic and the process to make it is by melting and casting.
 
I'd say it depends on the reason it needs to be cast; conductivity, thread sealing, strength, etc.

But probably not. The rule was made when cast boxes were metallic.
 
The problem I have is a project where we have already installed a lot of PVC FD boxes. Specifications asking for any kind of box, including non-metallic boxes, but a little note in the plan says we have to use "cast FD box". It does not say metal, or cast iron or aluminum.
I know "cast" is normally referred to metal boxes, iron or aluminum, but my question is if also you can consider a PVC box as "cast" by definition, because it is technically a "cast" box in its manufacturing process.
 
I thought that PVC boxes were manufactured by a mold injection process. Not sure if that's actually a casting process. Regardless I think that most would agree that when requiring a cast box it not intended to be PVC.
 
I meant PVC boxes weren't around when they decided cast boxes were needed in certain applications.

I.e., they were neither included nor excluded at the time.

I suggest asking whomever will be inspecting or approving the installation.
 
The PVC boxes were provided by the equipment company. We simply install the boxes and run conduit and cables. We can assume that this company has done this type of work many times before without problems, but the electrical engineer is asking for things above and beyond for no reason. Now we are in the dilemma of replacing the boxes or fighting against the "requirements".
 
infinity said:
I thought that PVC boxes were manufactured by a mold injection process. Not sure if that's actually a casting process. Regardless I think that most would agree that when requiring a cast box it not intended to be PVC.
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I try to find the definition of "cast" in some dictionaries. Most of them mention "pouring" the material in the mold but others only mentioned an object shaping in a mold. I agree that the term "cast" is typically used with metal boxes.
 
I think the distinction can be made that a "cast" FD or FS box is iron and has threaded hubs.

A PVC FS or FD box would be called a "PVC" FS or FD box and would have hubs suitable for glued PVC conduit.

So, I guess I should ask what conduit are you using? Although you could use PVC with adapters and cast FS or FD boxes, that makes little sense. Likewise, using threaded GRC with a PVC FS or FD box makes even less sense. Therefore, whatever conduit you use dictates the "accessories". If PVC conduit is specified, PVC boxes are appropriate. If someone specified "cast" with PVC conduit it's either leftover boilerplate or they don't know what they are talking about.

-Hal
 
Charlypt said:
I try to find the definition of "cast" in some dictionaries. Most of them mention "pouring" the material in the mold but others only mentioned an object shaping in a mold. I agree that the term "cast" is typically used with metal boxes.
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As an FYI, the Merriam-Webster 11th Collegiate Dictionary is the “official” dictionary for non-NFPA common terms.
 
Charlypt said:
The problem I have is a project where we have already installed a lot of PVC FD boxes. Specifications asking for any kind of box, including non-metallic boxes, but a little note in the plan says we have to use "cast FD box". It does not say metal, or cast iron or aluminum.
I know "cast" is normally referred to metal boxes, iron or aluminum, but my question is if also you can consider a PVC box as "cast" by definition, because it is technically a "cast" box in its manufacturing process.
Click to expand...
Wellll.... they're probably injection molded... gooey plastic squirted into a 2-part mold, where it cools. Once cool enough to hold its shape, the mold opens and out comes the molded (not cast!) part...
If you consider that the definition of 'cast' involves pouring.... often into a 2-part mold... where the part cools... Metal and plastic take similar paths to completion.
Fancy molds can cast threaded ports &c into a molded part...
 
Charlypt said:
The problem I have is a project where we have already installed a lot of PVC FD boxes. Specifications asking for any kind of box, including non-metallic boxes, but a little note in the plan says we have to use "cast FD box". It does not say metal, or cast iron or aluminum.
Click to expand...
I really think you are obsessing too much over this. Nowhere do the specs say anything about the material the box needs to be made of. You already installed a lot of PVC FD boxes. Has anybody ever called you on them saying they are not cast? If somebody actually does at some point just say, oh yeah, of course they are cast. How do you think they are made? Then walk away. :rolleyes:

-Hal
 
I would contact the engineering company and discuss this with them saying the equipment manufacturer supplied the materials.
 
Charlypt said:
The PVC boxes were provided by the equipment company. We simply install the boxes and run conduit and cables. We can assume that this company has done this type of work many times before without problems, but the electrical engineer is asking for things above and beyond for no reason. Now we are in the dilemma of replacing the boxes or fighting against the "requirements".
Click to expand...
Which of you is late to the party? If the electrical engineer had this on the plans or specs you bid to, shame on you for not paying attention. If the engineer is making this a requirement after the fun began, have him sign your change order and be about it.
 
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