Class 1,2 and 3 circuits for remote control, signaling and power-limited circuit

[A.K.]

I have the generator with generator control panel powered from generator batteries (24VDC with 1425 CCA system). My generator control panel power consumption is 3A continuous power draw and 12.5A power draw for 2 seconds pulse (closing generator circuit breaker signal). For power wiring and binary signal wiring I use XLPE 600V rated wire, for CAN cable 300V. Overcurrent protection located inside generator control panel.

Referencing to NEC70e 2020 article 725 please help me understand couple of things.
1. Is class 1 or class 2 I would consider for wiring between the engine batteries and the generator control panel (14AWG cables running through the panel mounted quick connector)? In article 725.121(A).5 it is say class 2 is "a battery source or battery source system that listed and identified as class 2"

2. Can I run "power wiring" (24VDC) from batteries to the generator control panel with other low-voltage wiring (24VDC binary signal wiring ) and CAN communication wiring from the engine in one non-metallic conduit through panel mounted quick connector? Or wires from batteries I need to run in separate conduit to maintain Class 1 and Class 2 separation? Referencing to the article 425.136.

Thanks,

 

[hbiss]

What does the manufacturer installation instructions say?

-Hal

 

[A.K.]

What does the manufacturer installation instructions say?

-Hal

I'm working on the generator manufacturing.

 

[A.K.]

What does the manufacturer installation instructions say?

-Hal

Mike, there is no manufacturing recommendations.

 

[don_resqcapt19]

... In article 725.121(A).5 it is say class 2 is "a battery source or battery source system that listed and identified as class 2"
...

See Chapter 9 Table 11)B) for the limitations on a Class 2 power source. For a generator, they typically use the starting battery as the control circuit power source. That would not be a Class 2 source as it is capable of supplying too much power.

 

[A.K.]

See Chapter 9 Table 11)B) for the limitations on a Class 2 power source. For a generator, they typically use the starting battery as the control circuit power source. That would not be a Class 2 source as it is capable of supplying too much power.

Thank you Don for quick respond. Referencing to the table 11(B)... since my wires (from battery to generator control panel (before 15A circuit breaker)), can provide over 1000/Vmax it will be considered as Class 1.

Referencing to my second question. What is your thoughts about placing this Class 1 circuit (XLPE 600V) with low voltage circuit (XLPE 600V) and communication wiring (shielded cable 250V) in single non-metallic flexible conduit. Referencing to the Article 725.136(H) "in Hoistways" or referencing to the exception #3 of 805.133(A)(1) (it is referencing to the article 620.36 "different systems in one raceway or traveling cable") where it stated that it can be run in same harness as long as cable insulated for the maximum voltage of the circuit...

2. Can I run "power wiring" (24VDC) from batteries to the generator control panel with other low-voltage wiring (24VDC binary signal wiring ) and CAN communication wiring from the engine in one non-metallic conduit through panel mounted quick connector? Or wires from batteries I need to run in separate conduit to maintain Class 1 and Class 2 separation (there is no example of traveling cable)? Referencing to the article 725.136.

thanks,

 

[hbiss]

Unless you plan on dropping that thing down an elevator shaft, nothing relating to a hoistway applies.

The rule is that if a power supply (source of power) is not listed or identified as Class 3 or Class 2 you must assume that it is Class 1 and wire accordingly. So in your case there is no such identification. Everything is Class 1.

As to running communication and signaling wiring with Class 1 conductors in the same raceway or conduit, the rules are very strict. Generally it boils down to "is the communications wiring necessary for the operation of the equipment or device that is powered by the Class 1 conductors?" In your case I would say yes. But there are requirements.

Your Class 1 XLPE is a 600V listed conductor which means that your communications conductors or cable must be listed as 600V also. (Doesn't matter what the actual voltage is.) Your #14's certainly can be THHN which would meet that requirement. But you mention a shielded cable which also must be 600V listed and that could be the deal breaker.

So whatever that shielded cable is, if you can't get it with a 600V listing, you are stuck with separate raceways.

Now, unless you have the manufacturers instructions that say something different, this is how I see it.

-Hal

 

[don_resqcapt19]

Thank you Don for quick respond. Referencing to the table 11(B)... since my wires (from battery to generator control panel (before 15A circuit breaker)), can provide over 1000/Vmax it will be considered as Class 1.

Referencing to my second question. What is your thoughts about placing this Class 1 circuit (XLPE 600V) with low voltage circuit (XLPE 600V) and communication wiring (shielded cable 250V) in single non-metallic flexible conduit. Referencing to the Article 725.136(H) "in Hoistways" or referencing to the exception #3 of 805.133(A)(1) (it is referencing to the article 620.36 "different systems in one raceway or traveling cable") where it stated that it can be run in same harness as long as cable insulated for the maximum voltage of the circuit...

2. Can I run "power wiring" (24VDC) from batteries to the generator control panel with other low-voltage wiring (24VDC binary signal wiring ) and CAN communication wiring from the engine in one non-metallic conduit through panel mounted quick connector? Or wires from batteries I need to run in separate conduit to maintain Class 1 and Class 2 separation (there is no example of traveling cable)? Referencing to the article 725.136.

thanks,

The Class 1 control circuit can be installed in the same raceway as the power conductors that are associated with that control circuit, so that is not an issue.

This is not a hoistway, and the rules in the section you cited will prohibit the communications cable from being in the same raceway with either the power conductors or the Class 1 control circuit conductors. If you are working off the 2020 code you could use Type TC cable for your communications circuit and put it in the same raceway with power and control cables. 725.136(I)
If you are on an earlier code, some AHJs may permit this using the provisions of 90.4 and grand special permission.

 

[don_resqcapt19]

.....
Your Class 1 XLPE is a 600V listed conductor which means that your communications conductors or cable must be listed as 600V also. (Doesn't matter what the actual voltage is.) Your #14's certainly can be THHN which would meet that requirement. But you mention a shielded cable which also must be 600V listed and that could be the deal breaker.
...
-Hal

What code section says that?

 

[hbiss]

Says what?

-Hal

 

[GerryB]

What code section says that?

would it be 725.49(B). I'm in 2017

 

[hbiss]

725.48 Conductors of Different Circuits in the Same Cable,
Cable Tray, Enclosure, or Raceway. Class 1 circuits shall be
permitted to be installed with other circuits as specified in
725.48(A) and (B).
(A) Two or More Class 1 Circuits. Class 1 circuits shall be
permitted to occupy the same cable, cable tray, enclosure, or
raceway without regard to whether the individual circuits are
alternating current or direct current, provided all conductors
are insulated for the maximum voltage of any conductor in the
cable, cable tray, enclosure, or raceway.

-Hal

 

[A.K.]

Great information. Thank you!!

 

[don_resqcapt19]

-Hal

I read your comment as including the shielded communications conductors. Those are not covered by that section as they are not Class 1 conductors.

 

[hbiss]

I read your comment as including the shielded communications conductors. Those are not covered by that section as they are not Class 1 conductors.

Correct, that's why I said I had a concern about the shielded cable and as I understand it, it is a cable, not conductors. If a shielded cable (or any cable) used for LV had to be run in the same raceway with Class 1 or power, the CABLE has to be listed for the same voltage as the Class 1 or power conductors are listed. This is why we suggest using tray cable (TC) in these instances as it is available with a 600V listing. This way, in essence, the cable jacket provides the necessary barrier or divider between the low voltage conductors inside of the cable and the power or Class 1 conductors run with it.

Problem is I'm not sure there is a type TC shielded cable. So if this does actually need to be shielded, he is pretty much out of luck with trying to run it with the other conductors in the same raceway.

-Hal

 

[don_resqcapt19]

Correct, that's why I said I had a concern about the shielded cable and as I understand it, it is a cable, not conductors. If a shielded cable (or any cable) used for LV had to be run in the same raceway with Class 1 or power, the CABLE has to be listed for the same voltage as the Class 1 or power conductors are listed. This is why we suggest using tray cable (TC) in these instances as it is available with a 600V listing. This way, in essence, the cable jacket provides the necessary barrier or divider between the low voltage conductors inside of the cable and the power or Class 1 conductors run with it.

Problem is I'm not sure there is a type TC shielded cable. So if this does actually need to be shielded, he is pretty much out of luck with trying to run it with the other conductors in the same raceway.

-Hal

If you are applying 300.3(C), the cables and conductors are not required to have the same voltage rating as each other, they only have to have a rating equal to or greater than the highest voltage that exists in the raceway.

Shielded Tray Cable is common for industrial projects, and the 2020 change to 725.136(I) specifically permits Type TC to be used for the required separation between Class 2 and 3 circuits and power or Class 1 circuits.

 

[shortcircuit2]

Below is a link to shielded tray cable...

Shielded 18-10 AWG - Advanced Digital Cable Inc.

Advanced Digital Cable Inc. Manufacturer of Electronic, IMSA Traffic, Industrial and RF Wire and Cable. Made In The USA

adcable.com

 

[shortcircuit2]

If you are working off the 2020 code you could use Type TC cable for your communications circuit and put it in the same raceway with power and control cables. 725.136(I)

IMO, 725.136(I) "Other Applications" does not pertain to wiring installed in a raceway. "Others Applications", for example would be open conductors, say a Article 398 installation or a Knob & Tube installation where 2-inch separation is required. Similar language is in 398.19 for the required 2-inch separation.

"Other Applications" previous to the 1996 NEC was referred to as "Open Conductors". See 1993 NEC 725-52(a) and 1996 NEC 725-54(3) where the language changed from "Open Conductors" to "Other Applications". "Other Applications" in early Code books was "Open Conductors"... see section 501 p. in 1935 NEC... section 6004 c. in 1935 NEC... section 7292 a. 1. in 1953 NEC... and section 725-42(a)(1) in 1971 NEC.

Section 725.136(I)(2) mentions the use of "porcelain tubes or flexible tubing", which were readily available at hardware stores in the early 19th century.

IMO, the language in 725.136(I) was manipulated for the development of "luminary cable"

"Other Applications" sections are also in article 760, 805, 820, 830. Are we permitted to put (PLFA) fire alarm circuit wiring in raceways with Class 1 and Power Wiring if we follow 760.136(G)?

 

[don_resqcapt19]

IMO, 725.136(I) "Other Applications" does not pertain to wiring installed in a raceway. "Others Applications", for example would be open conductors, say a Article 398 installation or a Knob & Tube installation where 2-inch separation is required. Similar language is in 398.19 for the required 2-inch separation.

"Other Applications" previous to the 1996 NEC was referred to as "Open Conductors". See 1993 NEC 725-52(a) and 1996 NEC 725-54(3) where the language changed from "Open Conductors" to "Other Applications". "Other Applications" in early Code books was "Open Conductors"... see section 501 p. in 1935 NEC... section 6004 c. in 1935 NEC... section 7292 a. 1. in 1953 NEC... and section 725-42(a)(1) in 1971 NEC.

Section 725.136(I)(2) mentions the use of "porcelain tubes or flexible tubing", which were readily available at hardware stores in the early 19th century.

IMO, the language in 725.136(I) was manipulated for the development of "luminary cable"

"Other Applications" sections are also in article 760, 805, 820, 830. Are we permitted to put (PLFA) fire alarm circuit wiring in raceways with Class 1 and Power Wiring if we follow 760.136(G)?

Ok, then just go to 725.136(A) and put the power conductors in a cable and we are good to go, as that rule only requires the Class 2 and 3 conductors or cables to be separated from power conductors, not from power cables.

 

[paulengr]

The glaring limitation here is no matter what you do, Category cable must be maximum #22 so it never meets the power cable minimum of #18 so must always be isolated in a separate class 1/2/3 raceway only.