ECN Forum Forums General Topics of the Trade General Discussion Area Low-V Trasnformer in the main service panel

Typical doorbell transformer in the panel. I rarely see this but can any one direct me to why or why not, in the NEC 2002, for this type of installation.
Thanks Joe

Do you mean mounted in a 1/2" KO in the panel? (only the line voltage leads inside) Otherwise how are you separating the class 2 wiring from the line voltage?

thanks for responding, No mounted inside the panel. no separation, all romex install, the low-v wires go out in an opening in the panel, panel is an exterior installation

[This message has been edited by JoeMed (edited 06-02-2005).]

725.55 ?

I'm ckecking it out and re-re reviewind article 450

"JoeMed I'm ckecking it out and re-re reviewind article 450"

Look at 450.1 ex2

450.1 Scope.
This article covers the installation of all transformers.

Exception No. 3: Transformers used with Class 2 and Class 3 circuits that comply with Article 725.

I need clarification on Class 1,2 and 3. Under 725 class 1 not more than 30v.
Can you advise? 725.21 (A)

The short answer is
Class 1, not current limited, treated virtually the same as "power"
Class 2, low voltage, current limited, like your doorbell.
Class 3, higher voltage, still current limited, like a phone line.