Lv divider

[jap]

I installed a 2g box behind my flat screen tv on the wall and used the orange Low Voltage Divider to seperate the Cable and the duplex receptacle.
I had a real hard time allowing myself to do this since I have been installing a completely different box for Data and Power at work in commercial building types all my career.
Then I got to wondering just how much protection that divider provides.
If it wasnt there what would actually happen?
I'm sure at some point in the attic of several houses the cable,telephone and romex run in close proximity to each other,so why do they have to be seperated in the box? I'm sure I'll get pounded with this one, but will the romex mysteriously rub into the TV cable? or what is the sole purpose behind having to seperate the low Voltage from the Higher voltage other than interference or the voltage rating of the insulation.

 

[pete m.]

I have always been in the understanding that if the line voltage faulted it could introduce that voltage onto the low-voltage in the same box.

Pete

 

[charlie b]

. . . if the line voltage faulted it could introduce that voltage onto the low-voltage in the same box.

That in turn could result in overheating of the LV wiring, and possibly a fire. The issue, or so I understand, is that the insulation system covering the LV wiring is not rated for the voltage available in the receptacle circuit. It is similar to the concern addressed in 300.3(C).

 

[jap]

By "Faulting" you are meaning that the line voltage physically got into the Coax?
Not simply an induction issue.
which makes me wonder why the seperation is only required inside the box and not throughout.

or is seperation required throughout?

I remember reading that the seperation was discontinued somewhere around 1998.

 

[infinity]

By "Faulting" you are meaning that the line voltage physically got into the Coax?
Not simply an induction issue.
which makes me wonder why the seperation is only required inside the box and not throughout.

or is seperation required throughout?

I remember reading that the seperation was discontinued somewhere around 1998.

The separation is required in the box because the outer jacket of the line voltage cable has been removed. Outside of the box the two cables can touch, even go through the same hole in the stud.

 

[pete m.]

Yes, I believe that the introduction of line voltage into a cable or conductors that are not rated for the higher voltage will be the issue as Charlie pointed out.

725.136
830.133(A)(1)(d)
820.133(A)(1)(b) - also see the exceptions
800.133(A)(1)(c)

Pete

 

[jap]

RG6 has a 300v Voltage rating.
Although I never would, i guess you still couldnt pass it through a 2g box without a LV Divider if you didnt terminate it inside the box?

 

[infinity]

RG6 has a 300v Voltage rating.
Although I never would, i guess you still couldnt pass it through a 2g box without a LV Divider if you didnt terminate it inside the box?

There are other limitations that would apply besides the insulation value. Pete M. gave a list of some of them. Even 600 volt conductors couldn't go in the same raceway as power conductors if they were fed from a class 2 power supply.