Wiring requirements for a networked lighting controller

[KJDCI]

Hi

We are selling a computerized lighting controller, and I want to make sure my information is correct. The idea is to show a before and after having added the lighting controller. This controller operates at line voltage (100 to 277 VAC). It is rated:

• UL Listed (CDN & US) UL 61010-1 Safety Requirements For Electrical Equipment For Measurement, Control, And Laboratory Use - Part 1: General Requirements - Edition 2 - Revision Date 2008/10/28
• CSA C22.2 NO. 61010-1 Safety Requirements For Electrical Equipment For Measurement, Control, And Laboratory Use - Part 1: General Requirements - Edition 2 - Revision Date 2008/10/01

Figure 1: Before



Figure 2: After retrofit.


This lighting controller (slave device) is networked together with a number of other controllers (including a master) and to wall devices through the "To / From Subnetwork" cabling. This cabling is standard Cat 5e network cable (with RS-485 data communication running through it). The control inputs (for the light switch) are low-voltage signalling dry-contact inputs (0-3.3 VDC).


Here are my questions:

1) Can the low voltage Cat 5e network cable be in the same enclosure without a barrier separating the low and high voltage sections? This is expensive and we would like to avoid this.
2) Will the Cat 5e network cable have to be rated as UL 444 making it suitable for 300 Volt applications? Otherwise, what cable should be used?
3) Can the Cat 5e network cable be installed outside of a conduit if it is FT-6 plenum cable, using appropriate methods (for example, keep the cable off of the ceiling tiles)?
4) Is it OK to reclassify the circuit for the control input? See NFPA 70, 300.3.(C)(1) in the context of a class 2 circuit that has been reclassified as a class 1 circuit [725.130(A) Ex2]. Is the control input circuit considered to be a class 2 circuit?

Thanks for your help!

 

[KJDCI]

Link to better quality Figure 2

Link to better quality Figure 2

I'm getting the swing of this site, so I've hosted a better quality image of Figure 2 offsite:

http://imageshack.com/a/img812/5112/ngax.png

 

[hbiss]

Who manufacturers it? I get the impression that its you?

-Hal

 

[Smart $]

1) I inclined to say no. See 800.133(A)(1)(d).

2) I believe rendered moot given reply above.

3) Plenum rated is a plus in this regard, but I have no idea what FT-6 means...

4) Someone will correct me if I'm wrong, but as I understand it, without looking up the particulars, using a Class 1 wiring method provides extra installation allowances for a Class 2 circuit but does not actually reclassify the circuit.

 

[GoldDigger]

3) Plenum rated is a plus in this regard, but I have no idea what FT-6 means...

It is a horizontal flame test rating under CSA standards which can, I believe, be an alternative to or addition to the UL plenum rating(s).
http://www.pacificcabling.com/Information/Information_other/flame_test_ratings.htm

 

[Smart $]

@KJDCI

I realize the figure is only a depiction, and includes the possibility of being used on L-L lighting loads. However, regarding the controller wiring, if used on a 120V lighting circuit, the grounded conductor would not have inline OCPD or be switched via the controller.

 

[KJDCI]

@KJDCI

I realize the figure is only a depiction, and includes the possibility of being used on L-L lighting loads. However, regarding the controller wiring, if used on a 120V lighting circuit, the grounded conductor would not have inline OCPD or be switched via the controller.

I'm sorry, I don't understand your point. Could you please break it down for me?

The controller has 4 outputs for lighting loads. Each output switches both the line and neutral with an internal relay.

What did you mean about L-L lighting loads?

Why would the controller's grounded conductor have an OCPD or be switched? This controller is double insulated. The ground to the controller is due to the European version that has 3-pin Wieland-type connectors for the lighting loads that include a ground conductor. In this scenario, there is no junction box.

Thanks for your reply and you help!

 

[Smart $]

I'm sorry, I don't understand your point. Could you please break it down for me?

The controller has 4 outputs for lighting loads. Each output switches both the line and neutral with an internal relay.

What did you mean about L-L lighting loads?

Why would the controller's grounded conductor have an OCPD or be switched? This controller is double insulated. The ground to the controller is due to the European version that has 3-pin Wieland-type connectors for the lighting loads that include a ground conductor. In this scenario, there is no junction box.

Thanks for your reply and you help!

Well, let's first establish your target region/country...? You are asking about NEC codes which are based on USA standards. Some non-US countries use the NEC for their electrical code, or sometimes it is job specific. However, issues arise due to non-US equipment being used.

As for the issue at hand, US electrical utilities supply several configurations which fall within the operating voltage of your controller. They are:

• 120V 1? 2W (W=wires; uncommon nowadays but still exist, residential only AFAIK)
• 120/208V 1? 3W (mostly residential; perhaps commercial but rare IMO)
• 120/240V 1? 3W (residential and commercial)
• 240/120V 3? 4W (mostly industrial/manufacturing, some commercial)
• 208/120V 3? 4W (some residential, industrial; mostly commercial/institutional)
• 480/240V 3? 4W (industrial)
• 480/277V 3? 4W (commercial, some industrial)

All the above highlighted red use a grounded neutral, which is not switched or have OCPD. All the above highlighted green are Line to Line (L-L) and both typically have OCPD; both are typically switched, but not required to be switched.

The wiring diagram will have to be different when using a grounded neutral supply conductor.

 

[hbiss]

The OP is a tech writer creating product documentation. I suggest that you get with your engineers who should be able to give you an explanation. I also suggest that they go through the UL or other NRTL listing process. Not only will it allow the product to be widely sold, it will address the design issues that have been brought up.

-Hal

 

[KJDCI]

Well, let's first establish your target region/country...? You are asking about NEC codes which are based on USA standards. Some non-US countries use the NEC for their electrical code, or sometimes it is job specific. However, issues arise due to non-US equipment being used.

As for the issue at hand, US electrical utilities supply several configurations which fall within the operating voltage of your controller. They are:

• 120V 1? 2W (W=wires; uncommon nowadays but still exist, residential only AFAIK)
• 120/208V 1? 3W (mostly residential; perhaps commercial but rare IMO)
• 120/240V 1? 3W (residential and commercial)
• 240/120V 3? 4W (mostly industrial/manufacturing, some commercial)
• 208/120V 3? 4W (some residential, industrial; mostly commercial/institutional)
• 480/240V 3? 4W (industrial)
• 480/277V 3? 4W (commercial, some industrial)

All the above highlighted red use a grounded neutral, which is not switched or have OCPD. All the above highlighted green are Line to Line (L-L) and both typically have OCPD; both are typically switched, but not required to be switched.

The wiring diagram will have to be different when using a grounded neutral supply conductor.

Thanks for clarifying L-L lighting loads and the OCPD requirements. It makes sense that a grounded neutral is not switched, nor should there be an OPCD.

The product is to be installed in the US. So the NEC 2011 applies...

What about 800.133(A)(2): Other applications? Is this anything opposed to 800.133(A)(1): Separation from other conductors, in raceways, cable trays, boxes, cables, and enclosures? No chance that simply keeping 2 inches of distance between the communications cable the the class 1 circuits will do?

In a larger sense, when you wire up a variable frequency drive (VFD) or a PLC, these devices today are normally networked with Ethernet cable (or some type of control network) while they are directly connected to class 1 motor circuits (240 - 480 volts). Is a permanent barrier always used? Does the VFD or PLC manufacturer normally sell this part? Or is it sold pre-mounted in an enclosure as a certified assembly?

Again thanks for your quick and thoughtful replies.

 

[Smart $]

...

What about 800.133(A)(2): Other applications? Is this anything opposed to 800.133(A)(1): Separation from other conductors, in raceways, cable trays, boxes, cables, and enclosures? No chance that simply keeping 2 inches of distance between the communications cable the the class 1 circuits will do?

In a larger sense, when you wire up a variable frequency drive (VFD) or a PLC, these devices today are normally networked with Ethernet cable (or some type of control network) while they are directly connected to class 1 motor circuits (240 - 480 volts). Is a permanent barrier always used? Does the VFD or PLC manufacturer normally sell this part? Or is it sold pre-mounted in an enclosure as a certified assembly? ...

800.133(A)(2) other applications are those not named specifically in 800.133(A)(1) title. Your application is in a [junction] box, which is named.

I see where you are going when bringing up VFD's and PLC's. It's a fine line. The NEC has an Article for Industrial Control Panels, but I believe it's mostly for field-fabricated ones. Manufacturers use other standards and/or testing (e.g. UL, NFPA 79) so the NEC only applies to the field wiring. FWIW, a lot of 'em simply use "Panduit" as the permanent barrier. Uncertain to what degree breakouts are scrutinized.

 

[KJDCI]

I see where you are going when bringing up VFD's and PLC's. It's a fine line. The NEC has an Article for Industrial Control Panels, but I believe it's mostly for field-fabricated ones. Manufacturers use other standards and/or testing (e.g. UL, NFPA 79) so the NEC only applies to the field wiring. FWIW, a lot of 'em simply use "Panduit" as the permanent barrier. Uncertain to what degree breakouts are scrutinized.

...

Well Panduit organizes things...

Yes NFPA 79 Electrical Standard for Industrial Machinery, Chapter 14, Wiring Practices appears to be more accommodating:

14.1.3 Conductors of Different Circuits. Conductors of different
circuits shall be permitted to be laid side by side and
occupy the same raceway (duct) (e.g., wireway or cable
trunking), or be in the same multiconductor cable assembly,
provided that the arrangement does not impair the
functioning of the respective circuit. Functionally associated
circuit conductors including power, control, remote
input/output, signaling, and communication cables shall
be permitted in the same raceway or cable assembly regardless
of voltage, provided all are insulated for the maximum
voltage of any circuit within the raceway or cable assembly.
Where those circuits operate at different voltages, the conductors
shall be separated by barriers or shall be insulated
for the highest voltage to which any conductor within the
same raceway (duct) or cable assembly is subjected.
Exception: Different voltage insulation levels or conductor properties
shall be permitted in the same cable assembly, provided the cable assembly
has been designed and tested to the identified application.


Thanks for your help!