MC Cable terminated in Arlington Siding Block?

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nhfire77

Senior Member
Location
NH
I was not able to find anything in the 05 NEC prohibiting it.

I've seen PVC bell boxes stamped "For use with nonmetallic raceways only," but not anything with Arlington. They have 1/2" KO's so you can properly land it.

I have run 1000's of feet of EMT with raintight connectors terminated in a PVC pull boxes, so why not right?

I am sure it is safe but...
 

nhfire77

Senior Member
Location
NH
So the Exception No.1 of 314.3 does permit metal raceways and metal cables with nonmetallic boxes, but only if an internal bonding means is provided in the box between all metal entries.

There is only one entry into the block, nothing to bond there.

There is a ground lug location (which Arlington provides location for a screw to be installed, and its required for a CSA covered install). I just add my own ground screw,

The armor is bonded at the panel, the clamp is bonded to the armor and there is a bonding terminal in the box... then its OK..... AND as long as its AHJ acceptable of course?

What about that?
 
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iwire

Moderator
Staff member
Location
Massachusetts
The armor is bonded at the panel, the clamp is bonded to the armor and there is a bonding terminal in the box... then its OK..... AND as long as its AHJ acceptable of course.
Sounds good to me but when this has come up before some sharp people felt very strongly the other way. :)
 

glene77is

Senior Member
Location
Memphis, TN
nhFire,
As I read Exeption #1, and #2, you are following the intent
by providing continuity to the EGC system.
The Handbook follows the same line of intent.
You could check the NEC Handbook to see if it reads like that to you. :)
 

iwire

Moderator
Staff member
Location
Massachusetts
What an difference of opinion? Here? Stop it.
I know ..... I know .... it is a shocking turn of events but this one time we could not come to an agreement. :grin:

My take is if you provide the bonding with a bonding bushing and some wire you would be fine, others feel it has to be factory provided.
 
This same topic came up in the UL breakout meeting of the UL Eastern Section meeting this fall.
The bonding means is required to be present in the box for metallic wiring methods or it is not permitted to terminate the metal wiring means to the nonmetallic enclosure. Nonmetallic enclosures are not designed for metallic wiring methods unless the bonding means is present.

The 2 exceptions do not account for the fact that the metallic wiring means is bonded somewhere else. One or the other listed boxes as described in the 2 exceptions would have to be used, and both types are available for sale.
 

nhfire77

Senior Member
Location
NH
This same topic came up in the UL breakout meeting of the UL Eastern Section meeting this fall.
The bonding means is required to be present in the box for metallic wiring methods or it is not permitted to terminate the metal wiring means to the nonmetallic enclosure. Nonmetallic enclosures are not designed for metallic wiring methods unless the bonding means is present.

The 2 exceptions do not account for the fact that the metallic wiring means is bonded somewhere else. One or the other listed boxes as described in the 2 exceptions would have to be used, and both types are available for sale.
So, in this specific case, the arlington siding block has a hole designed to accept a ground lug. Installing the ground lug is all that is required?

Since there is only one penetration into the block, bonding the armor is not necessary, but the lug must be present?

Sounds reasonable.

Since the spot for the lug is factory provided.... Adding a bonding bushing would not be necessary?

As previously stated the armor is bonded at the panel, would there be any reason at all to bond it? I mean you could bond it with a bonding bushing at the panel, and omit it at the device?
 
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nhfire77

Senior Member
Location
NH
I agree that if you had

MDP-----(line)------EMT-------{PVC J box}----------EMT.... (load)

The "load" side would need bonding to the line side otherwise it would be an ungrounded metallic raceway, but if there was only one penetration into the box, and it was continuous back to the panel or other applicable ground, you would not bond it in the PVC J box.
 
I agree that if you had

MDP-----(line)------EMT-------{PVC J box}----------EMT.... (load)

The "load" side would need bonding to the line side otherwise it would be an ungrounded metallic raceway, but if there was only one penetration into the box, and it was continuous back to the panel or other applicable ground, you would not bond it in the PVC J box.

Bonding of the wiring method is not part of the conditions set forth in the exceptions. The conditions of the exceptions are the bonding means that are required to be present in the nonnmetallic boxes installed.
 

nhfire77

Senior Member
Location
NH
Bonding of the wiring method is not part of the conditions set forth in the exceptions. The conditions of the exceptions are the bonding means that are required to be present in the nonnmetallic boxes installed.
Pierre,

Forgive me if, I am asking the same question a different way:

As long as the Bonding means (lets say a ground lug with screw) is in the nonmetallic box, it meets the exception?
 
Pierre,

Forgive me if, I am asking the same question a different way:

As long as the Bonding means (lets say a ground lug with screw) is in the nonmetallic box, it meets the exception?
No forgiveness necessary, I do not always understand some of the stuff I read here either.

Yes, if the bonding means as per listing are in the box, the exception is met...and the bonding is terminated.
 

PowerLink

Member
I am troubled by this application as a pvc box between two pieces of EMT would leave the conduit ungrounded weather or not there is a grounding lug provision within the box. If there were a fault within the EMT there would be a VERY unsafe condition. Only if the entrance were punched and a bond bushing were installed would I be okay with that.

Now that I think about it, there is another concern. What of the attachment screws? are they inside the pvc box and capable of becoming energized due to a short? Imagine a screw touching the wire mesh of a plaster wall becoming energized! You might get a new patent on that for a whole new era of "whole house heater".

Make it easy on yourself and purchase materials that are designed for the application.
 
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