Douglas Kaup
Member
- Location
- Decatur, AL USA
I work for an electronics company that specializes in PLC based control systems of remotely controlled field devices such as Door Locks, Utilities, etc.
The door locks are usually powered by 120Vac or 24Vdc, Lights are either 277Vac or 120Vac and of course receptacles are 120Vac.
We factory assemble our own industrial control panels which consist of PLC’s, Class-1 24Vdc power supplies, 24Vdc relays, single terminals and 24 gauge multiconductor cables (we don’t use Class 2 power for anything).
Our multiconductor control cable is a Belden 9543, 24 gauge 25 conductor jacketed CMG cable rated at 600V.
Our control cable connects PLC Outputs to 24Vdc relays for door control and Input modules connected to Door Position Switches located at the doors.
We have been assembling these control panels on hundreds of facilities over a time span of more than three decades. Recently we have encountered a very strict security consultant that won’t allow us to combine the 24 gauge control cable in the same Panduit wireway as conductors of other voltages and conductor sizes. The consultants reason is; the 24 gauge multi-conductor cable is considered Class 2 even though it’s source of power is from a Class 1 power supply.
Through my research of the NEC, I have found in code article 725.49 (A) permits 18awg and 16awg to be used as Class 1 circuits, but haven’t found any minimum conductor size for Class 2 or Class 3 circuits, nor have I found any exception that permits 24awg conductors powered from a Class 1 power supply to be permitted in factory assemblies or industrial control panels.
Are you aware of any NEC code article that would permit 24awg control wiring to be installed in the same (Panduit) raceway within a factory assembled industrial control panel?
The door locks are usually powered by 120Vac or 24Vdc, Lights are either 277Vac or 120Vac and of course receptacles are 120Vac.
We factory assemble our own industrial control panels which consist of PLC’s, Class-1 24Vdc power supplies, 24Vdc relays, single terminals and 24 gauge multiconductor cables (we don’t use Class 2 power for anything).
Our multiconductor control cable is a Belden 9543, 24 gauge 25 conductor jacketed CMG cable rated at 600V.
Our control cable connects PLC Outputs to 24Vdc relays for door control and Input modules connected to Door Position Switches located at the doors.
We have been assembling these control panels on hundreds of facilities over a time span of more than three decades. Recently we have encountered a very strict security consultant that won’t allow us to combine the 24 gauge control cable in the same Panduit wireway as conductors of other voltages and conductor sizes. The consultants reason is; the 24 gauge multi-conductor cable is considered Class 2 even though it’s source of power is from a Class 1 power supply.
Through my research of the NEC, I have found in code article 725.49 (A) permits 18awg and 16awg to be used as Class 1 circuits, but haven’t found any minimum conductor size for Class 2 or Class 3 circuits, nor have I found any exception that permits 24awg conductors powered from a Class 1 power supply to be permitted in factory assemblies or industrial control panels.
Are you aware of any NEC code article that would permit 24awg control wiring to be installed in the same (Panduit) raceway within a factory assembled industrial control panel?