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Low-V Trasnformer in the main service panel #52654
06/01/05 11:04 PM
06/01/05 11:04 PM
J
JoeMed  Offline OP
Member
Joined: Mar 2005
Posts: 16
Chino Valley Az. 86323
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
06/02/05 12:05 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,348
Estero,Fl,usa
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
06/02/05 12:23 AM
J
JoeMed  Offline OP
Member
Joined: Mar 2005
Posts: 16
Chino Valley Az. 86323
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
06/02/05 12:43 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,348
Estero,Fl,usa
725.55 ?


Greg Fretwell
Re: Low-V Trasnformer in the main service panel #52658
06/02/05 12:54 AM
06/02/05 12:54 AM
J
JoeMed  Offline OP
Member
Joined: Mar 2005
Posts: 16
Chino Valley Az. 86323
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
06/02/05 04:21 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,348
Estero,Fl,usa
"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
06/02/05 11:04 PM
J
JoeMed  Offline OP
Member
Joined: Mar 2005
Posts: 16
Chino Valley Az. 86323
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
06/03/05 12:29 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,348
Estero,Fl,usa
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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