Permanent Barrier or Listed Divider Examples Pull/Junction Box

[W@ttson]

Hello All,

I have seen the dividers used in small device boxes usually where switches or the like are used. Do you have pictures or examples of dividers being used in Large Pull or Junction boxes? The box I am looking at is about 36"x36"x24" NEMA 4X and will have Power, Class 1, FA, and Comm Cables. Need to divide it into 3 sections.

Thanks

 

[LarryFine]

I would think simple sheet-metal panels with folded edges for screws (like an end panel) would suffice.

 

[W@ttson]

I would think simple sheet-metal panels with folded edges for screws (like an end panel) would suffice.

Thank you for the reply. I guess the screws make it "Permanent".

If the comm, Class 1, FA are immediately sleeved into an inner-duct (non-split), would you consider that to be an acceptable permanent barrier?

 

[LarryFine]

If the comm, Class 1, FA are immediately sleeved into an inner-duct (non-split), would you consider that to be an acceptable permanent barrier?

I believe that would qualify.

 

[paulengr]

No such thing directly.

Inner duct is for fiber. I don’t recall this being mentioned for anything else.

NEC talks about 2” of isolation.

In medium voltage the controls are “isolated” from the power side. Of course it’s not 100% but most designs make it impossible to even do much as drop a nut into the power side.

Traditionally a lot of outdoor and control panels are built with hinged internal sub panels. Since all wiring is secured and isolated by a grounded metal panel no problems with that.

It’s legal to run say a power limited and power raceway (conduit or tray) side by side. Most consider it legal to even put a metal divider in and split a physical tray into two.

It’s typical to see say a PLC with 120 VAC non power limited power or even a 480 V power supply right next to it. To say nothing of an Ethernet jack less than an inch away. In fact I don’t see any realistic way that at some point (power supply) power limited and non power limited cables can’t be close to each other. But that’s a far cry from loose, unsecured wiring in a pull box compared to secured and landed on terminals. And NEC is pretty clear that outside of equipment general wiring and low power are separate just as you don’t run low voltage and medium voltage wiring together. So it seems like the issue here is you need more, smaller pull boxes.

 

[W@ttson]

No such thing directly.

Inner duct is for fiber. I don’t recall this being mentioned for anything else.

NEC talks about 2” of isolation.

In medium voltage the controls are “isolated” from the power side. Of course it’s not 100% but most designs make it impossible to even do much as drop a nut into the power side.

Traditionally a lot of outdoor and control panels are built with hinged internal sub panels. Since all wiring is secured and isolated by a grounded metal panel no problems with that.

It’s legal to run say a power limited and power raceway (conduit or tray) side by side. Most consider it legal to even put a metal divider in and split a physical tray into two.

It’s typical to see say a PLC with 120 VAC non power limited power or even a 480 V power supply right next to it. To say nothing of an Ethernet jack less than an inch away. In fact I don’t see any realistic way that at some point (power supply) power limited and non power limited cables can’t be close to each other. But that’s a far cry from loose, unsecured wiring in a pull box compared to secured and landed on terminals. And NEC is pretty clear that outside of equipment general wiring and low power are separate just as you don’t run low voltage and medium voltage wiring together. So it seems like the issue here is you need more, smaller pull boxes.

Doesn't 800.133 ( C ) say Comm cables shall not be run with power/lighting cables. But then Exception 1 immediately says that its OK if all power/lighting cables are separated from the Comm cables by a permanent barrier or listed divider.

That is where I am trying to get a consensus on, what are the ways that a permanent barrier can be constructed. So far I am looking at the sheet metal suggestion from Larry Fine, and the innerduct.

 

[LarryFine]

Instead of innerduct, use a standard wiring method, like conduit, flex (might need support), etc.

There's no rule against running a conduit through an enclosure, as long as you respect fill limits.

 

[qcroanoke]

I would think simple sheet-metal panels with folded edges for screws (like an end panel) would suffice.

Without a UL listing? Blasphemy!!!

 

[qcroanoke]

Instead of innerduct, use a standard wiring method, like conduit, flex (might need support), etc.

There's no rule against running a conduit through an enclosure, as long as you respect fill limits.

I have done that.

 

[don_resqcapt19]

Doesn't 800.133 ( C ) say Comm cables shall not be run with power/lighting cables. But then Exception 1 immediately says that its OK if all power/lighting cables are separated from the Comm cables by a permanent barrier or listed divider.

That is where I am trying to get a consensus on, what are the ways that a permanent barrier can be constructed. So far I am looking at the sheet metal suggestion from Larry Fine, and the innerduct.

Almost nothing an electrician installs is covered by Article 800. Even phone cables after the first item of customer owned equipment are covered by Article 725....but it really doesn't make any difference as the rules in 725 and 800 (now 805) are almost identical.

As far as the field made divider, I don't see an issue as boxes, are not required to be listed unless they are installed in a wet location. If I was inspecting, I would be looking for a divider of the same gauge as the enclosure walls.

 

[W@ttson]

Almost nothing an electrician installs is covered by Article 800. Even phone cables after the first item of customer owned equipment are covered by Article 725....but it really doesn't make any difference as the rules in 725 and 800 (now 805) are almost identical.

As far as the field made divider, I don't see an issue as boxes, are not required to be listed unless they are installed in a wet location. If I was inspecting, I would be looking for a divider of the same gauge as the enclosure walls.

very interesting about the listing. This will be in a wet location. Will look into this.

Thank you

 

[don_resqcapt19]

very interesting about the listing. This will be in a wet location. Will look into this.

Thank you

See 314.15