Maximum Raceway fill percentage for control cables (<50V, <1A)

[ashenafidemissie]

I have thousands of instrumentation and control cables (on a system <50V) and with very low current. Is there an exception to Maximum fill percentage of conduits (specified in chapter 9 table 1) when it comes to control cables?
I am asking this because control cables of low voltage and current doesn't produce much heat and easy for installation as compared to power cables.

 

[ramsy]

s there an exception to Maximum fill percentage of conduits (specified in chapter 9 table 1) when it comes to control cables?

If AHJ stamps the plans, clearly marked with conduit size & desired cable fill, then God blesses you --until client curses you--.

With no room for future expansion, or POE, and clear violation, client may file a claim against your GL policy for a free cable-tray remodel.

 

[GoldDigger]

I have thousands of instrumentation and control cables (on a system <50V) and with very low current. Is there an exception to Maximum fill percentage of conduits (specified in chapter 9 table 1) when it comes to control cables?
I am asking this because control cables of low voltage and current doesn't produce much heat and easy for installation as compared to power cables.

When the allowed flll is calcualted based on nominal wire guage rather than actual diameter, thinner insulation may make a small difference. The thermal load is not relevant for the percent filll calculation. You cannot pull the same number of a particular wire guage in practice if, for example, you choose to use PV wire with thick insulation.

 

[don_resqcapt19]

I have thousands of instrumentation and control cables (on a system <50V) and with very low current. Is there an exception to Maximum fill percentage of conduits (specified in chapter 9 table 1) when it comes to control cables?
I am asking this because control cables of low voltage and current doesn't produce much heat and easy for installation as compared to power cables.

The maximum percentage of fill has nothing to do with heat from the conductors. That issue is covered in Table 310.15(C), Adjustment Factors for More Than Three Current Carrying Conductors.

The physical fill rules are about preventing the conductors and cables from being damaged when they are installed. The manufacturers instructions for some types of cables used for instrumentation and controls are more restrictive than the code. I have seen instructions that specified a maximum of 30% fill, and no more than 270° of bend between pull points. They also often specify a maximum pulling force and I have seen that specified at 25 pounds for some cables.

 

[tom baker]

I have pulled thousands of feet of PLTC, Belden 1032A. It pulls harder than THHW. It can be damaged by excessive pulling force. Even installing to the max fill allowed by the NEC is difficult.