Class 1 circuit Classification

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MSWPCC54

Member
Location
Baltimore, MD
Hello Members,

The company I work for is having some issues with an electrical inspector in New Jersey. We built a switchgear enclosure that has a small walk in areas on both sides that needs to abide by the 2014 NEC. At first this guy told us we needed to separate ALL AC and DC circuits (for example by running all DC in blue conduit). I then responded to him with section 300.3(C). He then brought up section 725.48 and is asking us to identify the class of circuits on all the drawings and their combinations in their respective conduits/raceways etc.

I am relatively new to the industry so I lack some familiarity with the code. I understand what a class 2 and class 3 circuit classification means very well, however class 1 is tripping me up a little bit.

Do ALL control/signaling circuits need to be classified as class 1? For example 120VAC thermostat wiring or wiring to an ammeter?

If so my understanding is these circuits would need to be isolated from power/lighting cables not functionally associated with the control wiring.

Basically I'm looking for some further clarification on what qualifies a circuit as class 1 and any tips on the easiest way to satisfy my inspector.

Thanks
 

MSWPCC54

Member
Location
Baltimore, MD
A class 1 circuit is wired with a chapter 3 wiring method. There are two types, power limited and non power limited.

I get that it will be wired with the chapter 3 method. But would it need to be separated from non-associated power/lighting circuits per 725.48? or can it be run in a tray with other cables as long as the insulation rating is adequate?
 

Smart $

Esteemed Member
Location
Ohio
I get that it will be wired with the chapter 3 method. But would it need to be separated from non-associated power/lighting circuits per 725.48? or can it be run in a tray with other cables as long as the insulation rating is adequate?
725.48(B)(4) stipulations are straight forward... barrier separation required where not qualified under 725.48(B)(4)(2).
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
725.48(B)(4) stipulations are straight forward... barrier separation required where not qualified under 725.48(B)(4)(2).
But that separation does not require blue conduit or other bizarre details.
The wiring itself may not even require color or tag distinction as a separate voltage system since it is not a service or SDS?
Making it recognizable would still be a good idea.
In a cable tray a simple partition should be all that is needed.
 

Smart $

Esteemed Member
Location
Ohio
But that separation does not require blue conduit or other bizarre details.
I didn't say that it did, but otherwise I agree.

The wiring itself may not even require color or tag distinction as a separate voltage system since it is not a service or SDS?
Making it recognizable would still be a good idea.
This inspector will likely enforce identification of circuits under 210.5(C).
 

mwm1752

Senior Member
Location
Aspen, Colo
Hello Members,

The company I work for is having some issues with an electrical inspector in New Jersey. We built a switchgear enclosure that has a small walk in areas on both sides that needs to abide by the 2014 NEC. At first this guy told us we needed to separate ALL AC and DC circuits (for example by running all DC in blue conduit). I then responded to him with section 300.3(C). He then brought up section 725.48 and is asking us to identify the class of circuits on all the drawings and their combinations in their respective conduits/raceways etc. What is the voltage & type that needs to be separated -- Different volatges & types can be identified thru wire system coloring.

Do ALL control/signaling circuits need to be classified as class 1? For example 120VAC thermostat wiring or wiring to an ammeter? The NEC refers to Remote-Control, Signaling, that can use conductors as small as 18 awg. Your example could be a Class 1 Remote-Control and Signaling Circuit still has to be wired per Chapter 3..
ARTICLE 725
Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits
725.41 Class 1 Circuit Classifications and Power Source Requirements
Class 1 circuits shall be classified as either Class 1 power-limited circuits where they comply with the power limitations of 725.41(A) or as Class 1 remote-control and signaling circuits where they are used for remote-control or signaling purposes and comply with the power limitations of 725.41(B).
(B) Class 1 Remote-Control and Signaling Circuits. These circuits shall not exceed 600 volts. The power output of the source shall not be required to be limited.

If so my understanding is these circuits would need to be isolated from power/lighting cables not functionally associated with the control wiring.
almost sounds like (2) may be applicable
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).
(B) Class 1 Circuits with Power-Supply Circuits. Class 1 circuits shall be permitted to be installed with power-supply conductors as specified in 725.48(B)(1) through (B)(4).
(1) In a Cable, Enclosure, or Raceway. Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated.
(2) In Factory- or Field-Assembled Control Centers. Class 1 circuits and power-supply circuits shall be permitted to be installed in factory- or field-assembled control centers
 
Last edited:

MSWPCC54

Member
Location
Baltimore, MD
Hello Members,

The company I work for is having some issues with an electrical inspector in New Jersey. We built a switchgear enclosure that has a small walk in areas on both sides that needs to abide by the 2014 NEC. At first this guy told us we needed to separate ALL AC and DC circuits (for example by running all DC in blue conduit). I then responded to him with section 300.3(C). He then brought up section 725.48 and is asking us to identify the class of circuits on all the drawings and their combinations in their respective conduits/raceways etc. What is the voltage & type that needs to be separated -- Different volatges & types can be identified thru wire system coloring.

Do ALL control/signaling circuits need to be classified as class 1? For example 120VAC thermostat wiring or wiring to an ammeter? The NEC refers to Remote-Control, Signaling, that can use conductors as small as 18 awg. Your example could be a Class 1 Remote-Control and Signaling Circuit still has to be wired per Chapter 3..
ARTICLE 725
Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits
725.41 Class 1 Circuit Classifications and Power Source Requirements
Class 1 circuits shall be classified as either Class 1 power-limited circuits where they comply with the power limitations of 725.41(A) or as Class 1 remote-control and signaling circuits where they are used for remote-control or signaling purposes and comply with the power limitations of 725.41(B).
(B) Class 1 Remote-Control and Signaling Circuits. These circuits shall not exceed 600 volts. The power output of the source shall not be required to be limited.

If so my understanding is these circuits would need to be isolated from power/lighting cables not functionally associated with the control wiring.
almost sounds like (2) may be applicable
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).
(B) Class 1 Circuits with Power-Supply Circuits. Class 1 circuits shall be permitted to be installed with power-supply conductors as specified in 725.48(B)(1) through (B)(4).
(1) In a Cable, Enclosure, or Raceway. Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated.
(2) In Factory- or Field-Assembled Control Centers. Class 1 circuits and power-supply circuits shall be permitted to be installed in factory- or field-assembled control centers


Thank you all for the input.

That is a good idea. (2) may be applicable if this enclosure constitutes a "control center" it is factory assembled so that could work.
 

Smart $

Esteemed Member
Location
Ohio
Are the Article 725 circuits also covered by Article 210?
Well, 90.3 says Ch1-4 apply except as amended by Ch5-7. 725.3 excludes only Article 300 in general, but includes specific sections.

Shall we consider this an amendment (that really makes a difference)...
725.30 Class 1, Class 2, and Class 3 Circuit Identifica-
tion.
Class 1, Class 2, and Class 3 circuits shall be identi-
fied at terminal and junction locations in a manner that
prevents unintentional interference with other circuits dur-
ing testing and servicing.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Well, 90.3 says Ch1-4 apply except as amended by Ch5-7. 725.3 excludes only Article 300 in general, but includes specific sections. ...
My real question is "are Article 725 signaling and remote control circuits branch circuits?". I don't think they should be, but based on the definition in Article 100, they would be.
 

Smart $

Esteemed Member
Location
Ohio
My real question is "are Article 725 signaling and remote control circuits branch circuits?". I don't think they should be, but based on the definition in Article 100, they would be.
Exactly. Even as branch circuits, very little of Article 210 will apply. Just happens that Identification of Ungrounded Conductors is one that does.
 
Hello Members,

The company I work for is having some issues with an electrical inspector in New Jersey. We built a switchgear enclosure that has a small walk in areas on both sides that needs to abide by the 2014 NEC. At first this guy told us we needed to separate ALL AC and DC circuits (for example by running all DC in blue conduit). I then responded to him with section 300.3(C). He then brought up section 725.48 and is asking us to identify the class of circuits on all the drawings and their combinations in their respective conduits/raceways etc. What is the voltage & type that needs to be separated -- Different volatges & types can be identified thru wire system coloring.

Do ALL control/signaling circuits need to be classified as class 1? For example 120VAC thermostat wiring or wiring to an ammeter? The NEC refers to Remote-Control, Signaling, that can use conductors as small as 18 awg. Your example could be a Class 1 Remote-Control and Signaling Circuit still has to be wired per Chapter 3..
ARTICLE 725
Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits
725.41 Class 1 Circuit Classifications and Power Source Requirements
Class 1 circuits shall be classified as either Class 1 power-limited circuits where they comply with the power limitations of 725.41(A) or as Class 1 remote-control and signaling circuits where they are used for remote-control or signaling purposes and comply with the power limitations of 725.41(B).
(B) Class 1 Remote-Control and Signaling Circuits. These circuits shall not exceed 600 volts. The power output of the source shall not be required to be limited.

If so my understanding is these circuits would need to be isolated from power/lighting cables not functionally associated with the control wiring.
almost sounds like (2) may be applicable
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).
(B) Class 1 Circuits with Power-Supply Circuits. Class 1 circuits shall be permitted to be installed with power-supply conductors as specified in 725.48(B)(1) through (B)(4).
(1) In a Cable, Enclosure, or Raceway. Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated.
(2) In Factory- or Field-Assembled Control Centers. Class 1 circuits and power-supply circuits shall be permitted to be installed in factory- or field-assembled control centers



I would like further clarification on this. The NEC defines class 1 circuits as the two types as mentioned, however there isn't any clear direction that I've found on whether a circuit that does controls, "must" fall under class 1, or "is permitted to" fall under class 1.

The issue I have is because class I and power circuits need to be in separate raceways, I would rather just classify everything as "power" rather than class 1 to keep it all in 1 conduit. I realize this means stricter limits on ampacity modification as well as conductor sizing can't be smaller than 14AWG, but is there any issue with doing this? It seems like power circuits have stricter requirements than class 1 so I would think this would be fine but would appreciate some feedback.
 

Smart $

Esteemed Member
Location
Ohio
I would like further clarification on this. The NEC defines class 1 circuits as the two types as mentioned, however there isn't any clear direction that I've found on whether a circuit that does controls, "must" fall under class 1, or "is permitted to" fall under class 1.
If the circuit does not provide power to any equipment it is associated with, then it is not a power circuit. In the Instrumentation & Control field, it would have to electrically power a final control element(s). Google that term to get a better understanding.

The issue I have is because class I and power circuits need to be in separate raceways, I would rather just classify everything as "power" rather than class 1 to keep it all in 1 conduit. I realize this means stricter limits on ampacity modification as well as conductor sizing can't be smaller than 14AWG, but is there any issue with doing this? It seems like power circuits have stricter requirements than class 1 so I would think this would be fine but would appreciate some feedback.
Power and class 1 control circuits can be in the same raceway as long as the class 1 circuits are associated with a load that [one of] the power circuits supply. Note the criteria does not say other power and control circuit conductors cannot be in the same raceway. JMO, YMMV
 
If the circuit does not provide power to any equipment it is associated with, then it is not a power circuit. In the Instrumentation & Control field, it would have to electrically power a final control element(s). Google that term to get a better understanding.


Power and class 1 control circuits can be in the same raceway as long as the class 1 circuits are associated with a load that [one of] the power circuits supply. Note the criteria does not say other power and control circuit conductors cannot be in the same raceway. JMO, YMMV

Thank you very much Smart $ for the reply.
 
you can also just convert them via a procedure found in article 725 so they are no longer class 1 circuits and then you can run them as you see fit.

I'm aware of the procedure the convert class 2 circuits into class 1, but am not aware of a procedure to convert class 1 into power circuits. Can you point me more specifically in article 725?
 
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