Power Limitations Per Tables 11(A) and 11(B) located in Chapter 9.
Maximum Power Supply size for Class 2 Circuits is 100 VA.

There are extensive requirements to keep Class 2 and Class 3 open circuit conductors separated from Power and Lighting and Class 1 Circuit conductors.

Power Source must be from a LISTED Class 2, Class 3 power supply, or from LISTED Information Technology Equipment, or from a small battery.

Cables located outdoors in cable trays must be type PLTC.
In Hazardous Locations type PLTC, or any of the Types listed in Section 501.4 that includes 300 volt Type ITC cable.

Cables in indoor cable trays shall be types PLTC, MPP, MPR, MPG, MP, CMP, CMR, CMG, CM, CL3P, CL3R, CL3, CL2P, CL2R, and CL2.

Wiring in Hazardous Locations must comply with Articles 501 through 517.

Where run outdoors and above ground Class 2 and Class 3 circuits that are subject to accidental contact with power and lighting conductors over 300 volts to ground or that are subject to lightning must be grounded with a grounding electrode the same way communication circuits are grounded.

Work must be performed in a neat and workmanlike manner.

Major Changes to Article 725 in the 2002 NEC

2002 NEC Changes

NEW Definition: Section 725-2 has new definition for Abandoned Class 2, Class 3, and PLTC Cable. " Installed Class 2, Class 3, and PLTC cable that is not terminated at equipment and not identified for future use with a tag."

NEW Section 725.3(B) added: "The accessible portion of abandoned Class 2, Class 3, and PLTC cables shall not be permitted to remain. "

Revision. Section 725.6 has been revised to require that Class 1, Class 2, and Class 3 circuit conductors be installed in a neat and workmanlike manner and that they be properly supported using structural components of the building. "Such cables shall be attached to the structural components using straps, staples, hangers, or similar fittings designed and installed so as to not damage the cable."

Class 2 and Class 3 Circuits in MC cable permitted in Cable tray with power, etc.

The general rule is that cables and conductors of Class 2 and Class 3 circuits shall not be placed in any cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar fitting with conductors of electric light, power, Class 1, nonpower-limited fire alarm circuits, and medium and high power network-powered broadband communication cables. A new exception has been added to an already long list of exceptions.
Section 725.55(H) permits Class 2 and Class 3 circuits in type MC Metal Clad cable to be installed in the same cable tray with conductors of electric light, power, Class 1, nonpower-limited fire alarm circuits, and medium and high power network-powered broadband communication cables.

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	Power Limitations Per Tables 11(A) and 11(B) located in Chapter 9. Maximum Power Supply size for Class 2 Circuits is 100 VA.

	There are extensive requirements to keep Class 2 and Class 3 open circuit conductors separated from Power and Lighting and Class 1 Circuit conductors.

	Power Source must be from a LISTED Class 2, Class 3 power supply, or from LISTED Information Technology Equipment, or from a small battery.

	Cables located outdoors in cable trays must be type PLTC. In Hazardous Locations type PLTC, or any of the Types listed in Section 501.4 that includes 300 volt Type ITC cable.

	Cables in indoor cable trays shall be types PLTC, MPP, MPR, MPG, MP, CMP, CMR, CMG, CM, CL3P, CL3R, CL3, CL2P, CL2R, and CL2.

	Wiring in Hazardous Locations must comply with Articles 501 through 517.

	Where run outdoors and above ground Class 2 and Class 3 circuits that are subject to accidental contact with power and lighting conductors over 300 volts to ground or that are subject to lightning must be grounded with a grounding electrode the same way communication circuits are grounded.

	Work must be performed in a neat and workmanlike manner.