4" square Box Problem

[LarryFine]

Does that fitting provide the equivalent protection of a bushing?

Now that you mention it, PVC male adapters do tend to have a sharp throat. I have rounded them over before.

 

[Dennis Alwon]

Isn't informational note just information and not enforcable?

Also, I can agree that on PVC you don't have as much chance to damage the conductors but could the intent of the plastic bushing be there to protect the PVC fitting form getting damaged while pulling the wires. (you know how the pulling medium cuts into the fitting)

There are tools you can used to avoid the fish tape, rope, string, etc from cutting into the connector. The NEC doesn't say I have to install the bushing before I pull the wire. If so , then I have always been in violation. :grin:

 

[Little Bill]

No, because it's a fitting.


I don't know what you mean. I ask why no bushing was needed, was it because PVC is smooth and wouldn't damage conductors. I thought the bushing went on the fitting to protect the wires. So what does, "because it's a fitting" mean?

 

[Ponchik]

The NEC doesn't say I have to install the bushing before I pull the wire. If so , then I have always been in violation. :grin:

If I really think about it i wonder what is the purpose of the bushing? In reality once the conductors are pulled, and the connection are made and the junction box is closed off, the wires don't move and there shouldn't be any damage to the wires. Right?

 

[Cavie]

No, because it's a fitting.


I don't know what you mean. I ask why no bushing was needed, was it because PVC is smooth and wouldn't damage conductors. I thought the bushing went on the fitting to protect the wires. So what does, "because it's a fitting" mean?

352.46 .........a bushing OR adapter shall............. PVC connectors are not connectors and they re not fittings. They are called adapters. Why? I don't know. 1st base. PVC Male adapters and PVC Female adapters. Most have beveled flared throats. In over 40 years I have never put a bushing on PVC adaptors having smaller that #4 wire. Some have longer threads than others. Some you can't get a locknut and a bushing on because of the short threads.

 

[Little Bill]

adapter[/COLOR] shall............. PVC connectors are not connectors and they re not fittings. They are called adapters. Why? I don't know. 1st base. PVC Male adapters and PVC Female adapters. Most have beveled flared throats. In over 40 years I have never put a bushing on PVC adaptors having smaller that #4 wire. Some have longer threads than others. Some you can't get a locknut and a bushing on because of the short threads.

I think we have some inspectors here that need to read 352.46. I have a electrician friend that told me the inspector made him put one on PVC with #12 and I ask an inspector about where I had to add some PVC to protect some conductors going into the panel if I needed the bushing and he said I did, even though they were 6AWG conductors.
This discussion really clears things up for me.

 

[Strife]

No, because it HAS to be smaller than #4 what you pulling in that 3/4" pipe. Code requires bushings on #4 and larger.

Why, because it is PVC?

 

[Dennis Alwon]

If I really think about it i wonder what is the purpose of the bushing? In reality once the conductors are pulled, and the connection are made and the junction box is closed off, the wires don't move and there shouldn't be any damage to the wires. Right?

IMO the purpose of the bushing is to protect the wire when it is bent perpendicular to the entry to protect the wire from the edges of the conduit.

Pvc can be a bit sharp while emt is a bit rounded so perhaps that is why pvc is req. bushings for all sizes. Not really enforced around here unless it is #4 or larger.

 

[hurk27]

352.46 Bushings. Where a conduit enters a box, fitting, or other enclosure, a bushing or adapter shall be provided to
protect the wire from abrasion unless the box, fitting, or enclosure design provides equivalent protection.

I believe 352.46 and 344.46 apply to all conductors? And if any conduit has #4 and larger, regardless of the conduit or the connector it has to have a bushing.

There is only one kind of a conduit that "Enters a Box" and it is threaded

PVC does not "Enter a Box" unless threaded and uses lock nuts not fittings, I don't think anyone installs threaded PVC
EMT does not "Enter a Box"

The enter a fitting that "Enters a Box"

This was the respond by the CMP's at an IAEI western sectional meeting in response to this very question.

 

[Dennis Alwon]

PVC does not "Enter a Box" unless threaded and uses lock nuts not fittings, I don't think anyone installs threaded PVC
EMT does not "Enter a Box"

The enter a fitting that "Enters a Box"

So it says to bush the pvc when it enters the fitting-- pray tell how one does that.....:grin:

352.46 Bushings. Where a conduit enters a box, fitting, or other enclosure, a bushing or adapter shall be provided

 

[GUNNING]

supository

supository

Ya fold it in half and apply a little heat to straighten then insert.

 

[hurk27]

So it says to bush the pvc when it enters the fitting-- pray tell how one does that.....:grin:

There are fittings with thin threaded walls that a threaded conduit can thread through with the conduit entering the fitting, Is a condulet a fitting, I have seen this with them where a conduit enters the side, but I agree that this code seems kind of strange that it was copied verbatim to one conduit article that you don't ever thread ENT? 362.46 as far as I know?

it starts with IMC:
342.46 IMC
344.46 RMC
352.46 PVC
353.46 HDPE
354.46 NUUC
355.46 RTRC
362.46 ENT

IMC and RMC talks about threading which none of the others do.
EMT which doesn't have this .46 bushing requirement, but does state "shall not be threaded" in 358.28, its the only one out of the above articles that directly prohibits threading

I have seen threaded PVC, as for the others with the exception of ENT I don't know, never used them, now for ENT which I have always known as smurf tubing, unless there is a different kind of ENT, I can say that I can not see threading of smurf.

What is stranger is if this was meant for any size wires why not include a .46 bushing requirement in 358 for EMT? FMC? or a few others?

Now what is even stranger is the definition of a fitting in article 100:

Fitting. An accessory such as a locknut, bushing, or other
part of a wiring system that is intended primarily to perform
a mechanical rather than an electrical function.

So does this mean you need a bushing for a bushing?

I think someone was sleeping on the job when these .46 bushing requirments was added.

 

[hurk27]

I think it's iconic that in the above list of articles with the .46 bushing requirment that IMC and RMC are the only two metal raceways, the rest are all non metallic, wow if that wire was to short out to the PVC what in the world would happen? nothing:roll:

 

[cecseabee]

Box fittings

Box fittings

The problem created by side entry could be eliminated with a plaster ring, if applicable; use of a PVC box may also eliminate the problem since PVC boxes are normally threaded so the box connector could be installed.

 

[Dennis Alwon]

It all comes down to whether or not an ahj considers a pvc connector as providing adequate protection. I know that PVC connectors can be sharp but if the wire just passes thru it should be no issue. It is hard to imagine a #12 wire that would get cut with a pvc connector unless you really jam it down over the connector. I guess the cmp has to cover all cases and it is too hard to spell it out for each case.

 

[kwired]

Box adaptors, first I've seen in brown. All I've used were same color as PVC. I like these too & use them wherever I can. Great for minimum protrusion.

I'd love it too, if each size of PVC would fit into the next larger size. Couplings could easily be made in a pinch, oversize LB's could easily be used for large stiff wire, etc. Supply houses around here don't sell PVC size adaptors. The big box stores have a few sizes sometimes.

I remember years ago using fittings as well as PVC conduit that would adapt to next size. Sometimes wish it was still around. OD of 1/2 inch coupling would fit into a 3/4 fitting was easy to reduce. You also only really needed to stock FS boxes in 3/4 sizes. The bell ends of 1/2 conduit would also fit into a 3/4 fitting.

Where's the money in that?

Why did they start putting bell ends on the pipe when they could sell more couplings? When PVC was fairly new it did not have bell ends, or at least some of it did not.

Isn't informational note just information and not enforcable?

Also, I can agree that on PVC you don't have as much chance to damage the conductors but could the intent of the plastic bushing be there to protect the PVC fitting form getting damaged while pulling the wires. (you know how the pulling medium cuts into the fitting)

Pulling medium cuts through bushing just as easy as the fitting.

There are fittings with thin threaded walls that a threaded conduit can thread through with the conduit entering the fitting, Is a condulet a fitting, I have seen this with them where a conduit enters the side, but I agree that this code seems kind of strange that it was copied verbatim to one conduit article that you don't ever thread ENT? 362.46 as far as I know?

it starts with IMC:
342.46 IMC
344.46 RMC
352.46 PVC
353.46 HDPE
354.46 NUUC
355.46 RTRC
362.46 ENT

IMC and RMC talks about threading which none of the others do.
EMT which doesn't have this .46 bushing requirement, but does state "shall not be threaded" in 358.28, its the only one out of the above articles that directly prohibits threading

I have seen threaded PVC, as for the others with the exception of ENT I don't know, never used them, now for ENT which I have always known as smurf tubing, unless there is a different kind of ENT, I can say that I can not see threading of smurf.

What is stranger is if this was meant for any size wires why not include a .46 bushing requirement in 358 for EMT? FMC? or a few others?

Now what is even stranger is the definition of a fitting in article 100:



So does this mean you need a bushing for a bushing?

I think someone was sleeping on the job when these .46 bushing requirments was added.

There are grounding bushings that do not require a locknut be installed first. The bushing is the locknut, a bushing and provides a place to connect a grounding conductor.

 

[jmellc]

352.46 Bushings. Where a conduit enters a box, fitting, or other enclosure, a bushing or adapter shall be provided to
protect the wire from abrasion unless the box, fitting, or enclosure design provides equivalent protection.

I believe 352.46 and 344.46 apply to all conductors? And if any conduit has #4 and larger, regardless of the conduit or the connector it has to have a bushing.

A connector with smooth edges meets the definition of providing equivalent protection, as I see it.

 

[jmellc]

Where's the money in that?

Maybe not having to run out for a coupling if you run short & have scraps of next larger conduit. I'll take any small help I can get. Savings in time & fuel.

 

[jmellc]

adapter[/COLOR] shall............. PVC connectors are not connectors and they re not fittings. They are called adapters. Why? I don't know. 1st base. PVC Male adapters and PVC Female adapters. Most have beveled flared throats. In over 40 years I have never put a bushing on PVC adaptors having smaller that #4 wire. Some have longer threads than others. Some you can't get a locknut and a bushing on because of the short threads.

I did a little work with 4" PVC recently. The 4" male adaptor had the shortest threads I've ever seen. You'd think it should be other way around.