12VDC in conduit with 120/VAC

[wirebender]

I have a conduit run to a junction box with 6 circuits (208 3ph) in it.
I am planning on using it for emergency circuits for a generator install.
I only need 4 of the circuits.
I also need 12vdc from the gennie to this location for an annunciator panel.
Can I use the extra 2 wires for this 12vdc?

Thanks,
Tony Hill

 

[ibew441dc]

I have a conduit run to a junction box with 6 circuits (208 3ph) in it.
I am planning on using it for emergency circuits for a generator install.
I only need 4 of the circuits.
I also need 12vdc from the gennie to this location for an annunciator panel.
Can I use the extra 2 wires for this 12vdc?

Thanks,
Tony Hill

I say no, based on 700.9(B)

700.9 Wiring, Emergency System.

(A) Identification. All boxes and enclosures (including transfer switches, generators, and power panels) for emergency circuits shall be permanently marked so they will be readily identified as a component of an emergency circuit or system.

(B) Wiring. Wiring of two or more emergency circuits supplied from the same source shall be permitted in the same raceway, cable, box, or cabinet. Wiring from an emergency source or emergency source distribution overcurrent protection to emergency loads shall be kept entirely independent of all other wiring and equipment, unless otherwise permitted in (1) through (5):

(1) Wiring from the normal power source located in transfer equipment enclosures

(2) Wiring supplied from two sources in exit or emergency luminaires

(3) Wiring from two sources in a common junction box, attached to exit or emergency luminaires

(4) Wiring within a common junction box attached to unit equipment, containing only the branch circuit supplying the unit equipment and the emergency circuit supplied by the unit equipment

(5) Wiring from an emergency source to supply any combination of emergency, legally required, or optional loads in accordance with (a), (b), and (c):

a. From separate vertical switchboard sections, with or without a common bus, or from individual disconnects mounted in separate enclosures.

b. The common bus or separate sections of the switchboard or the individual enclosures shall be permitted to be supplied by single or multiple feeders without overcurrent protection at the source.

Exception to (5)(b): Overcurrent protection shall be permitted at the source or for the equipment, provided the overcurrent protection is selectively coordinated with the downstream overcurrent protection.

c. Legally required and optional standby circuits shall not originate from the same vertical switchboard section, panelboard enclosure, or individual disconnect enclosure as emergency circuits.

 

[brother]

I have a conduit run to a junction box with 6 circuits (208 3ph) in it.
I am planning on using it for emergency circuits for a generator install.
I only need 4 of the circuits.
I also need 12vdc from the gennie to this location for an annunciator panel.
Can I use the extra 2 wires for this 12vdc?

Thanks,
Tony Hill

check out 2008 NEC 300.3(C)(1) and remember to read the FPN it sends you to 725.136(A) for class 2 and class 3 circuit conductors.

 

[wirebender]

Thank you, gentlemen.

 

[iwire]

I have a conduit run to a junction box with 6 circuits (208 3ph) in it.
I am planning on using it for emergency circuits for a generator install.
I only need 4 of the circuits.
I also need 12vdc from the gennie to this location for an annunciator panel.
Can I use the extra 2 wires for this 12vdc?

Thanks,
Tony Hill

First off we have to be clear ...... are these really 'emergency circuits' covered by Article 700 in which case I fully agree with ibew441dc that 700.9 prohibits it.

But if these circuits are really 'optional standby circuits' covered by Article 702 things change.

If 700.9 does not apply possible issue would be 110.3(B) and the generator installation instructions and Article 725. There are ways around the Prohibitions in 725 by re-classifying Class 2 and 3 circuits.

All that said, I would keep them separate.

 

[Twoskinsoneman]

First off we have to be clear ...... are these really 'emergency circuits' covered by Article 700 in which case I fully agree with ibew441dc that 700.9 prohibits it.

But if these circuits are really 'optional standby circuits' covered by Article 702 things change.

If 700.9 does not apply possible issue would be 110.3(B) and the generator installation instructions and Article 725. There are ways around the Prohibitions in 725 by re-classifying Class 2 and 3 circuits.

All that said, I would keep them separate.

Let me ask this... Even following the different rules that allow power conductors to be run in the same conduit with remote control, signaling, power limited... isn't it always a stipulation that the circuits go to equipment that is functionally associated?

 

[iwire]

isn't it always a stipulation that the circuits go to equipment that is functionally associated?

No, you can field 're-classify' a class 2 or 3 circuit, however once you do this you know must treat the entire circuit as a class 1 circuit
See 2005 (the '8s in the truck) 725.52(A) Exception 2. In the 08 code I think it has been relocated about 50 sections ahead.

 

[cpal]

No, you can field 're-classify' a class 2 or 3 circuit, however once you do this you know must treat the entire circuit as a class 1 circuit
See 2005 (the '8s in the truck) 725.52(A) Exception 2. In the 08 code I think it has been relocated about 50 sections ahead.

this from the explanatory notes in the 08 HB
Section 725.130 permits the following two distinct wiring methods for circuits connected to Class 2 or Class 3 power sources:
? Class 1 wiring methods
? Class 2 and Class 3 wiring methods
Where it is necessary to locate Class 2 or Class 3 circuits inside the same cable or raceway as a Class 1 circuit, 725.130(A), Exception No. 2, permits a Class 2 or Class 3 circuit to be reclassified and installed as Class 1, providing that the Class 2 or Class 3 marking is removed, that overcurrent protection is provided in accordance with 725.43, and that the reclassified circuit maintains separation from other Class 2 and Class 3 circuits in accordance with 725.136.

 

[iwire]

Thanks for posting this handbook commentary.

I wish the editors would choose their words more carefully.

this from the explanatory notes in the 08 HB
Section 725.130 permits the following two distinct wiring methods for circuits connected to Class 2 or Class 3 power sources:
? Class 1 wiring methods
? Class 2 and Class 3 wiring methods
Where it is necessary to locate Class 2 or Class 3 circuits inside the same cable or raceway as a Class 1 circuit, 725.130(A), Exception No. 2, permits a Class 2 or Class 3 circuit to be reclassified and installed as Class 1, providing that the Class 2 or Class 3 marking is removed, that overcurrent protection is provided in accordance with 725.43, and that the reclassified circuit maintains separation from other Class 2 and Class 3 circuits in accordance with 725.136.

IMO they should not have said 'necessary', they should have used a word more like 'desired' etc. I know a small point but when the objective of the text is to clarify the NEC proper wording is essential.

JMHO.

 

[Twoskinsoneman]

No, you can field 're-classify' a class 2 or 3 circuit, however once you do this you know must treat the entire circuit as a class 1 circuit
See 2005 (the '8s in the truck) 725.52(A) Exception 2. In the 08 code I think it has been relocated about 50 sections ahead.

Right, I know you can reclassify class 2 or 3 to be class 1... But class 1 can only be installed in the same raceway as power conductors if they associated... At least I thought.

725.48
(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.

 

[iwire]

Right, I know you can reclassify class 2 or 3 to be class 1... But class 1 can only be installed in the same raceway as power conductors if they associated... At least I thought.

(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.

I will be honest, I just learned something. I was unaware that I could not always run Class 1 with power conductors.

Now after reading the section I don't think it is a stretch at all that a generator annunciator is functionally associated the generator.

 

[Twoskinsoneman]

I will be honest, I just learned something. I was unaware that I could not always run Class 1 with power conductors.

Now after reading the section I don't think it is a stretch at all that a generator annunciator is functionally associated the generator.

This is obviously an AHJ judgment call but remember the equipment

being powered needs to be associated not the power source.

I have a hard time believing the equipment powered by the 4 power circuits in the raceway can be called functionally associated... That is a REAL stretch IMO

added by editing

 

[iwire]

Well then I guess we just see it differently. :smile:

 

[Twoskinsoneman]

Well then I guess we just see it differently. :smile:

I think you have dug your heels in and can not see the forest for the trees....:roll:

Lets say one of the 4 circuits is powering a light. Please explain how that light if "functional associated" with the annunciator...

I'm guessing the explanation will sound more like "six degrees of separation" than functional association...:grin:

 

[wirebender]

Please explain how that light if "functional associated" with the annunciator...

You need the light to see the annunciator panel.:grin:

Keep talking Bob, you nearly got me talked into it.

 

[iwire]

Lets say one of the 4 circuits is powering a light. Please explain how that light if "functional associated" with the annunciator...

All the conductors are functionally associated with the generator.

The Annunciator is supplied by the generator

The 4 circuits are supplied by the generator

All five items are functionally associated with the generator the conduit runs from.

Can you give me an example of your view of functionally associated conductors are? In other words when would that section be applicable to any installation?

 

[don_resqcapt19]

All the conductors are functionally associated with the generator.

The Annunciator is supplied by the generator

The 4 circuits are supplied by the generator

All five items are functionally associated with the generator the conduit runs from.

Can you give me an example of your view of functionally associated conductors are? In other words when would that section be applicable to any installation?

I don't see those circuits as functionally associated. An example of functionally associated would be the motor control circuit conductors in the same raceway as the power circuit conductors for that same motor.

 

[iwire]

I don't see those circuits as functionally associated. An example of functionally associated would be the motor control circuit conductors in the same raceway as the power circuit conductors for that same motor.

Your motor example for sure. As for the other, OK I concede.

 

[Twoskinsoneman]

I don't see those circuits as functionally associated. An example of functionally associated would be the motor control circuit conductors in the same raceway as the power circuit conductors for that same motor.

Exactly. The example I see most (MH books) is air conditioner power conductors and thermostat control. Of course the entire thermo circuit would have to be chapter 3 so it probably wouldn't be very practical.

 

[LarryFine]

I'm more interested in whether we're allowed to run the four control wires in the same conduit as the feeder for a generator.

After all, two wires carry 240v and the other two carry 12v, at least with Generac residential units, and they're run together.

Then, there's the battery charger some have, along with the block heater for water-cooled units. They're all associated, right?