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Low-V Trasnformer in the main service panel #52654 06/01/05 11:04 PM
Joined: Mar 2005
Posts: 16
J
JoeMed Offline OP
Member
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

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Re: Low-V Trasnformer in the main service panel #52655 06/02/05 12:05 AM
Joined: Jul 2004
Posts: 9,513
G
gfretwell Offline
Member
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?


Greg Fretwell
Re: Low-V Trasnformer in the main service panel #52656 06/02/05 12:23 AM
Joined: Mar 2005
Posts: 16
J
JoeMed Offline OP
Member
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).]

Re: Low-V Trasnformer in the main service panel #52657 06/02/05 12:43 AM
Joined: Jul 2004
Posts: 9,513
G
gfretwell Offline
Member
725.55 ?


Greg Fretwell
Re: Low-V Trasnformer in the main service panel #52658 06/02/05 12:54 AM
Joined: Mar 2005
Posts: 16
J
JoeMed Offline OP
Member
I'm ckecking it out and re-re reviewind article 450

Re: Low-V Trasnformer in the main service panel #52659 06/02/05 04:21 PM
Joined: Jul 2004
Posts: 9,513
G
gfretwell Offline
Member
"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.


Greg Fretwell
Re: Low-V Trasnformer in the main service panel #52660 06/02/05 11:04 PM
Joined: Mar 2005
Posts: 16
J
JoeMed Offline OP
Member
I need clarification on Class 1,2 and 3. Under 725 class 1 not more than 30v.
Can you advise? 725.21 (A)

Re: Low-V Trasnformer in the main service panel #52661 06/03/05 12:29 AM
Joined: Jul 2004
Posts: 9,513
G
gfretwell Offline
Member
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.


Greg Fretwell

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