Cable tray in Class II, Division 2 locations

[don_resqcapt19]

I have an application where I want to install control and instrument cables in a cable tray that passes through a Class II, Division 2 area. All of the circuits operate at 150 volts or less and 5 amps or less. These cables would be digital and analog control circuits from field instruments to a DCS. There would also be motor control circuits for motors that are controlled by the DCS. There would be no connections or terminations of the cables in the Class II, Division 2 area.

502.10(B)(4) appears to permit this application where PLTC cables are used, however if also references Article 725. I am not finding any direct reference to this installation in Article 725.

There is also a permission to use ITC in 502.10(B)(5) and I don't find any restrictions in Article 727.

I am trying to get away from the spacing requirements as found in 502.10(B)(6), but the engineer is saying that even the instrument and control circuits have to comply with the spacing requirement.

 

[petersonra]

I have an application where I want to install control and instrument cables in a cable tray that passes through a Class II, Division 2 area. All of the circuits operate at 150 volts or less and 5 amps or less. These cables would be digital and analog control circuits from field instruments to a DCS. There would also be motor control circuits for motors that are controlled by the DCS. There would be no connections or terminations of the cables in the Class II, Division 2 area.

502.10(B)(4) appears to permit this application where PLTC cables are used, however if also references Article 725. I am not finding any direct reference to this installation in Article 725.

There is also a permission to use ITC in 502.10(B)(5) and I don't find any restrictions in Article 727.

I am trying to get away from the spacing requirements as found in 502.10(B)(6), but the engineer is saying that even the instrument and control circuits have to comply with the spacing requirement.

what code version are you looking at? 502.10(B)(6) in the 2011 version only applies to Type MC, MI, or TC cable.

 

[don_resqcapt19]

what code version are you looking at? 502.10(B)(6) in the 2011 version only applies to Type MC, MI, or TC cable.

2014, but it is the same as 2011. The engineer is saying that (B)(6) applies to the control cables. I think that problem is that Type TC is used for both power and control.

How is it different if we install the same circuits in Type TC or in Type PLTC or ITC?

 

[rbalex]

In Class II, the primary concern is surface heat, especially where dust accumulation is possible. Good "housekeeping" will usually eliminate concerns in Division 2 for most installations but that can be difficult with elevated cable trays.

With regard to Sections 502.10(B)(4) and (5) the only restrictions are that they are installed per Articles 725 or 727 respectively. No spacing is specified since surface heat isn't a concern for otherwise properly installed cables even with surface accumulations unless they were sufficient to create a Division 1 location.

For MC, MI, or TC cables spacing can be a concern.

 

[rbalex]

2014, but it is the same as 2011. The engineer is saying that (B)(6) applies to the control cables. I think that problem is that Type TC is used for both power and control.

How is it different if we install the same circuits in Type TC or in Type PLTC or ITC?

Basically, since the NEC is based on visual field inspection and cables are marked as ITC, PLTC or TC it identifies which Subsection of 502.10(B) (4),(5) or (6) applies. However, to answer the underlined question this is one reason why Section 500.8(A) was developed; especially 500.8(A)(3). Any reasonable evaluation would say Type TC, installed per either Article 725 or 727 would be suitable.