door bells
- Thread starter ies
- Start date
- Status
peter d
Senior Member
- Location
- New England
Re: door bells
The NEC.
The NEC.
jeff43222
Senior Member
- Location
- Minneapolis, Minnesota
Re: door bells
Thanks for clearing that up, Peter.
Thanks for clearing that up, Peter.
peter d
Senior Member
- Location
- New England
Re: door bells
Anytime. I'm glad I could assist you.
Anytime. I'm glad I could assist you.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: door bells
If you have conductors that serve loads of different voltage classes, then they can share a raceway if, and only if, every conductor has an insulation system that is rated for the highest voltage class that is represented in the raceway.
That said, any city, county, state, or other legal jurisdiction can set their own rules, and can enforce those rules within the geographical limits of their jurisdiction. The "C" word in "NEC" is a bit of presumption on the part of the NFPA. Nothing becomes "Code," until one or more legal jurisdictions enact it into their laws.
If you have conductors that serve loads of different voltage classes, then they can share a raceway if, and only if, every conductor has an insulation system that is rated for the highest voltage class that is represented in the raceway.
That said, any city, county, state, or other legal jurisdiction can set their own rules, and can enforce those rules within the geographical limits of their jurisdiction. The "C" word in "NEC" is a bit of presumption on the part of the NFPA. Nothing becomes "Code," until one or more legal jurisdictions enact it into their laws.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: door bells
But would this apply to class 2 wiring which door bells tend to use?
peter d
Senior Member
- Location
- New England
Re: door bells
In the case of the OP's doorbell question, that means we would have to use a button rated for 120 volts, wire the circuit with a chapter 3 method, find a chime rated for 120 volts, etc etc. It isn't worth it in most cases.
Yes, but it doesn't end there. We still must follow 725.55. But, if we choose to "reclassify" as allowed by 725.52 Exception 2, we must then wire the entire circuit as a Class 1 method.
In the case of the OP's doorbell question, that means we would have to use a button rated for 120 volts, wire the circuit with a chapter 3 method, find a chime rated for 120 volts, etc etc. It isn't worth it in most cases.
jeff43222
Senior Member
- Location
- Minneapolis, Minnesota
Re: door bells
I don't do much doorbell work, but when I do, I keep the wires separate from the power wires. That way I don't have to remember all the code that refers to doorbells.
I don't do much doorbell work, but when I do, I keep the wires separate from the power wires. That way I don't have to remember all the code that refers to doorbells.
pierre
Senior Member
- Location
- Westchester County, New York
Re: door bells
"725.55 Separation from Electric Light, Power, Class 1, Non?Power-Limited Fire Alarm Circuit Conductors, and Medium Power Network-Powered Broadband Communications Cables.
(A) General. 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, non?power-limited fire alarm circuits, and medium power network-powered broadband communications circuits unless permitted by 725.55(B) through (J).
This tells us that in general, regardless of the insulation type, that Class 2 wiring cannot be installed in the same raceway as power and lighting conductors.
(D) permits under strict requirements for Class 2 to be installed in the same enclosures, boxes, and similar fittings .
Lets not forget...
"(J) Other Applications. For other applications, conductors of Class 2 and Class 3 circuits shall be separated by at least 50 mm (2 in.) from conductors of any electric light, power,
Class 1 non?power-limited fire alarm or medium power network-powered broadband communications circuits unless one of the following conditions is met:
(1) Either (a) all of the electric light, power, Class 1, non?power-limited fire alarm and medium power networkpowered broadband communications circuit conductors or (b) all of the Class 2 and Class 3 circuit conductors are in a raceway or in metal-sheathed, metal-clad, non?metallic-sheathed, or Type UF cables.
(2) All of the electric light, power, Class 1 non?powerlimited fire alarm, and medium power networkpowered broadband communications circuit conductors are permanently separated from all of the Class 2 and Class 3 circuit conductors by a continuous and firmly fixed nonconductor, such as porcelain tubes or flexible tubing, in addition to the insulation on the conductors.
"725.55 Separation from Electric Light, Power, Class 1, Non?Power-Limited Fire Alarm Circuit Conductors, and Medium Power Network-Powered Broadband Communications Cables.
(A) General. 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, non?power-limited fire alarm circuits, and medium power network-powered broadband communications circuits unless permitted by 725.55(B) through (J).
This tells us that in general, regardless of the insulation type, that Class 2 wiring cannot be installed in the same raceway as power and lighting conductors.
(D) permits under strict requirements for Class 2 to be installed in the same enclosures, boxes, and similar fittings .
Lets not forget...
"(J) Other Applications. For other applications, conductors of Class 2 and Class 3 circuits shall be separated by at least 50 mm (2 in.) from conductors of any electric light, power,
Class 1 non?power-limited fire alarm or medium power network-powered broadband communications circuits unless one of the following conditions is met:
(1) Either (a) all of the electric light, power, Class 1, non?power-limited fire alarm and medium power networkpowered broadband communications circuit conductors or (b) all of the Class 2 and Class 3 circuit conductors are in a raceway or in metal-sheathed, metal-clad, non?metallic-sheathed, or Type UF cables.
(2) All of the electric light, power, Class 1 non?powerlimited fire alarm, and medium power networkpowered broadband communications circuit conductors are permanently separated from all of the Class 2 and Class 3 circuit conductors by a continuous and firmly fixed nonconductor, such as porcelain tubes or flexible tubing, in addition to the insulation on the conductors.
peter d
Senior Member
- Location
- New England
Re: door bells
Case in point: Many electricians will run both the control and power conductors through the same whip for an AC unit using THWN/THHN. So far, so good. Then they will run the low voltage conductors into the building via the disconnect, sans raceway, and simply wire nut the two THWN's onto a piece of class 2 thermostat cable. They use the above code (300.3(C)(1)as justification while ignoring the FPN right under it.
This is a persistent trade "semi-myth" in that the above is true, but the other pertinent code articles are ignored or misunderstood.
Case in point: Many electricians will run both the control and power conductors through the same whip for an AC unit using THWN/THHN. So far, so good. Then they will run the low voltage conductors into the building via the disconnect, sans raceway, and simply wire nut the two THWN's onto a piece of class 2 thermostat cable. They use the above code (300.3(C)(1)as justification while ignoring the FPN right under it.
- Status