ITC-ER CABLE USES

[lpena]

Hi, I need to use cable type ITC-ER. The cable will be installed on a class I div 2 location. Looking at the NEC, I see that ITC-ER is acceptable to use on haz. locations, however, 727.5 says that the cable cannot be used on circuits operating at more than 150 Volts or more than 5 Amperes. I have no problem with the Voltage rating. I am planning to use this cable to wire analog transmitters (4-20 mA signals), but i am not sure if am meeting the current requirement. I will be using a 20 Amp, 24VDC to power the transmitters/loop power. But, I have 5 Amps fuses after the power supply for individuals circuits. Also each transmitter is fused (1A). By having these fuses, do i meet the current requirement for 727.5, or do i need to change my power supply, so that its output no more than 5 Amps? Thanks. See attached for wiring sketch for better understanding.

 

[GoldDigger]

Hi, I need to use cable type ITC-ER. The cable will be installed on a class I div 2 location. Looking at the NEC, I see that ITC-ER is acceptable to use on haz. locations, however, 727.5 says that the cable cannot be used on circuits operating at more than 150 Volts or more than 5 Amperes. I have no problem with the Voltage rating. I am planning to use this cable to wire analog transmitters (4-20 mA signals), but i am not sure if am meeting the current requirement. I will be using a 20 Amp, 24VDC to power the transmitters/loop power. But, I have 5 Amps fuses after the power supply for individuals circuits. Also each transmitter is fused (1A). By having these fuses, do i meet the current requirement for 727.5, or do i need to change my power supply, so that its output no more than 5 Amps? Thanks. See attached for wiring sketch for better understanding.

That is a very specialized question.
PLTC (Power Limited Tray Cable), with the ER suffix for exposed run outside the tray, is recognized for specific uses in 725, and can be used in place of CL2 or CL3 types as shown in Table 725.154(G).
I think that as long as either Class 2 or Class 3 fits your power supply limits, you should be OK electrically.
But(!) just limiting the current to 5A with a fuse does not necessarily make a power supply conform to Class 2 specifications and would not justify putting a Class 2 label on it.
So the question that still needs an answer from somebody who does this work: What are the exact power limitations of PLTC and can it only be used where it is directly called out in 725 or is used as a substitute for another (i.e. CL) cable type.
CL2 cable, AFAIK, can only be used with a listed Class 2 power source.

Note also that there are power supplies with multiple outputs and integral current limiting on each output terminal that deliver an aggregate current well above 5A but are NRTL listed as Class 2. Possibly getting one of those instead of putting in your own fuses would be the way to go.

 

[lpena]

GoldDigger, you are talking about PLTC cables (Power limited). I was actually referring to ITC-ER (Instrumentation Tray Cable) Section 727. After, further reading article 727.5. It says that type ITC cable shall not be installed with power, lighting, class 1 circuits not power limited or non-power limited circuits. According to 724.41 (A) a class 1 power limited circuit has a rated output of not more than 30 Volts and 1000 VA. My 24 VDC power supply is rated 480 Watts (or 480 VA), therefore it can be considered a power limited source, so I'd say is is OK to use this power supply with ITC-ER cables. What do you think?

 

[GoldDigger]

GoldDigger, you are talking about PLTC cables (Power limited). I was actually referring to ITC-ER (Instrumentation Tray Cable) Section 727. After, further reading article 727.5. It says that type ITC cable shall not be installed with power, lighting, class 1 circuits not power limited or non-power limited circuits. According to 724.41 (A) a class 1 power limited circuit has a rated output of not more than 30 Volts and 1000 VA. My 24 VDC power supply is rated 480 Watts (or 480 VA), therefore it can be considered a power limited source, so I'd say is is OK to use this power supply with ITC-ER cables. What do you think?

Sounds right to me.