Thread: Transformer & Low Volt Wiring in Main Panel

Hello to all,

I am trying to find section in IRC that addresses whether, or not, a transformer and its low voltage wiring can be housed inside a main electrical panel. (Maybe this is a NEC issue instead?)

In this case the transformer is in bottom of panel (not even mounted - literally hanging by its line voltage wiring, and the low voltage wiring passes along the right side and out the top of the panel (about 2.5 feet worth).

Thanks for your help.

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Not allowed.

IRC. (underling is mine)
- E3303.3 Listing and labeling. Electrical materials, components, devices, fixtures and equipment shall be listed for the application, shall bear the label of an approved agency and shall be installed, and used, or both, in accordance with the manufacturer’s installation instructions.

- SECTION E4204
- - INSTALLATION REQUIREMENTS

- - - E4204.1 Separation from other conductors.

In cables, compartments, enclosures, outlet boxes, device boxes, and raceways, conductors of Class 2 circuits shall not be placed in any cable, compartment, enclosure, outlet box, device box, race way, or similar fitting with conductors of electric light, power, Class 1 and nonpower-limited fire alarm circuits.

- - - - Exceptions:
- - - - - 1. Where the conductors of the electric light, power, Class 1 and nonpower-limited fire alarm circuits are separated by a barrier from the Class 2 circuits. In enclosures, Class 2 circuits shall be permitted to be

installed in a raceway within the enclosure to separate them from Class 1, electric light, power and nonpower-limited fire alarm circuits. (Jerry's note: This exception does not apply.)

- - - - - -2. Class 2 conductors in compartments, enclosures, device boxes, outlet boxes and similar fittings where electric light, power, Class 1 or nonpower-limited fire alarm circuit conductors are introduced solely to connect to the equipment connected to the Class 2 circuits. The electric light, power, Class 1 and nonpower-limited fire alarm circuit conductors shall be routed to maintain a minimum of 1/4 inch (6.4 mm) separation from the conductors and cables of the Class 2 circuits; or the electric light power, Class 1 and nonpower-limited fire alarm circuit conductors operate at 150 volts or less to ground and the Class 2 circuits are installed using Types CL3, CL3R, or CL3P or permitted substitute cables, and provided that these Class 3 cable conductors extending beyond their jacket are separated by a minimum of 1/4 inch (6.4 mm) or by a nonconductive sleeve or nonconductive barrier from all other conductors. (Jerry's note: This exception does not apply.)

- E4204.2 Other applications.

Conductors of Class 2 circuits shall be separated by not less than 2 inches (51 mm) from conductors of any electric light, power, Class 1 or nonpower-limited fire alarm circuits except where one of the following conditions is met: (Jerry's note: This does not apply.)
- - 1. All of the electric light, power, Class 1 and nonpower-limited fire alarm circuit conductors are in raceways or in metal-sheathed, metal-clad, nonmetallic-sheathed or Type UF cables.
- - 2. All of the Class 2 circuit conductors are in raceways or in metal-sheathed, metal-clad, nonmetallic-sheathed or Type UF cables.

The NEC will say the same basic thing - do not run Class 2 circuits with power and lighting circuit conductors and not in the same enclosures ... unless the Class 2 circuit conductors are entering the enclosure to operate the equipment. An example of this is an AHU which has power circuit conductors enter the AHU as do the Class 2 circuit conductors. The Class 2 circuit conductors are allowed to enter-and-terminate within the AHU. The Class 2 circuit conductors would not, however, be allowed to enter-and-pass-through-without-terminating-within the AHU.

Thanks Jerry!

IRC 2003
Section
e4204.1 Separation from other conductors
In cables, compartments, enclosures, outlet boxes, device boxes, and raceways, conductors of Class 2 circuits shall not be placed in any cable, compartment, enclosure, outlet box, cevice box, raceway or similar fitting with conductors of electric light, power, Class 1 and not power-limited fire alarm circuits.

Jim

Does any one know how long this code has been part of the IRC. I had a realtor jump down my throat today because he was "sure" that the low voltage wiring and transformer could be installed in the electrical panel in 1984. I explained I didn't know for sure what the code was in 1984, but I know that it isn't right NOW for a REASON. Anyway, it would be VERY helpful if anyone could tell me when this was put into affect, or at least if it was in effect 1984.

It's not the IRC you should refer to but the NEC.

It's been in the NEC for decades, I'm sure before the 1984 even.

Thanks Jerry. I'm a little confused though, isn't what you quoted above from the IRC? It loose like you quoted the IRC and stated the NEC would say the same.

If I needed to, what would be my best avenue to to verify that this was in affect in 1984 (without having all the IRC / NEC revisions available to me).

Thanks again...

Andrew,

I quoted the IRC because that is what I had access to at the time - and as I said the NEC says the same thing.

I don't have my codes with me, but I am pretty sure that such separation was required long before 1984.

Your best response is to simply say that, to your knowledge, such separation has been required basically 'forever' and that it is up to the electrician to provide documentation to the contrary, and if an electrician can prove that it came later, your report will still list it because it is not safe-as current codes acknowledge.

Put it back on the electrician to deem it as 'safe' because you know it is not.

This sounds like the transformer for the door chime. This is also a pretty common installation.
As a side note: this would only be a Class 2 circuit if the transformer is labeled "class 2" on the body of the transformer regardless of what it is used for. So most of the above stated code for class 2 circuits may not apply.

Originally Posted by Roland Miller

This sounds like the transformer for the door chime. This is also a pretty common installation.

Yes, that is an all too common installation.

As a side note: this would only be a Class 2 circuit if the transformer is labeled "class 2" on the body of the transformer regardless of what it is used for.

Not necessarily correct. I do not have the NEC with me, but, while a Class 2 circuit is required to be identified as such, not being identified does not make it a non-Class 2 circuit, it's use makes it a Class 2 circuit, and then it should be labeled as such.

If it is not a transformer that is listed and labeled as Class 2 then it is not a class 2 circuit--end of story. If it is, then the class 2 circuit installation rules apply.

Other wise you cannot simply say it is a class 2 circuit by its use...there would be no way it say it is by some field design or stretch of the imagination a class 2 circuit.

Originally Posted by Roland Miller

If it is not a transformer that is listed and labeled as Class 2 then it is not a class 2 circuit--end of story. If it is, then the class 2 circuit installation rules apply.

Other wise you cannot simply say it is a class 2 circuit by its use...there would be no way it say it is by some field design or stretch of the imagination a class 2 circuit.

As I am always open to learning something new ... please state how you would classify that low voltage (probably 10 volts to 16 volts) door bell circuit and what requirements, if any, are there prohibiting/allowing that circuit in with the 120 volt / 240 volt wiring.

Class 2 circuits (not over 30 volts at 100 VA inherently limited power source) include wiring for thermostats, programmable controllers, burglar and security systems, as well as limited-energy voice, intercom, background music, sound systems, and public address systems. This generally includes a common door bell circuit. And the load side installation requirements are as Jerry has underlined in his post.

What I am saying is you don't know to classify this circuit as a Class 2 unless the Power Class 2 ac inherently limited power sources is durably marked where plainly visible to indicate the class of supply and electrical rating. If you can't find this information on the transformer then it may end up classified as Class 1, power limited circuit and different load side code applies.

Placing the transformer inside the panel has been common practice but is currently an NEC code violation.

Originally Posted by Roland Miller

If it is not a transformer that is listed and labeled as Class 2 then it is not a class 2 circuit--end of story. If it is, then the class 2 circuit installation rules apply.

Other wise you cannot simply say it is a class 2 circuit by its use...there would be no way it say it is by some field design or stretch of the imagination a class 2 circuit.

Sorry Roland, but we don't follow you there.

If it has no label, we may have to make an assumpition, and we check the leads from the secondary winding. If they are a light gauge #18 or #22 or such, we know that transformer is not putting out a high voltage. We can take a voltage measurement if we felt any doubt about it. Most of us have seen enough doorbell/thermostat/alarm system transformers in residential electrical systems that we don't need to see a label to know it is extremely likely to be Class 2.

Then we call for an electrician to repair, and if he finds it to be otherwise, he can say something about it then.

In my area it is rare to see the transformer inside the panel. It has never been permitted, so only a homeowner add-on would be done that way.

I understand....TMI for the average HI. Making an assumption is probably the best way.

Originally Posted by John Kogel

Sorry Roland, but we don't follow you there.

I was trying to give a simple, no-brainer way of identifying a Class 2 circuit that works anywhere-- anytime. Look for the label. If it is not there it is not a Class 2 circuit....

Originally Posted by Roland Miller

I was trying to give a simple, no-brainer way of identifying a Class 2 circuit that works anywhere-- anytime. Look for the label. If it is not there it is not a Class 2 circuit....

The best no brainer way is to simply look at the wiring - most will use thermostat cable, which is going to be labeled as Class 2 wiring. If the circuit contains ANY Class 2 wiring then the entire circuit is a Class 2 circuit.

Originally Posted by Jerry Peck

The best no brainer way is to simply look at the wiring - most will use thermostat cable, which is going to be labeled as Class 2 wiring. If the circuit contains ANY Class 2 wiring then the entire circuit is a Class 2 circuit.

!!!!!

An unlisted, unlabeled plane jane "transformer" or componant is not a listed "Class 2" Power Supply.

I just picked a couple of random inspections and checked for low voltage transformers. No labels. What are we supposed to do if there's no labels?

Here's another one. I know they are low voltage transformers. I know the low voltage wiring must not be in close quarters with high voltage wiring. Do I need to call it a Class 2 circuit in my report? No, 'low voltage circuit' is all we need.

Class 2 only if it becomes a code translation issue, which wouldn't happen here.
Because every reputable electrician in Canada knows the doorbell tranny does not go inside the panel, ever.

Originally Posted by H.G. Watson, Sr.

!!!!!

An unlisted, unlabeled plane jane "transformer" or componant is not a listed "Class 2" Power Supply.

Watson,

I see you are into your BIG, BOLD and COLOR is some how more real and accurate sham again ...

Any conductors identified as Class 2 are deemed part of a Class 2 as those conductors are required to be re-identified as other than Class 2 if they are not being used for Class 2 circuits - thus, if thermostat cable, which is identified as being Class 2 on the outer jacket, is used, then the circuit is deemed to be Class 2 until proven otherwise, and, when proven otherwise, the Class 2 cable is required to be re-identified as not being Class 2.

Think of it as using Class 2 labeled transformer on circuit which is not a Class 2 circuit and you and Roland stating that it is therefore a Class 2 circuit ... the Class 2 identified cable is considered as Class 2 unless it has been re-identified as being other than Class 2.

The code does not allow Class 2 identified wiring to be used in other than Class 2 circuits. There IS more to it than just having a Class 2 identified transformer.

Originally Posted by Jerry Peck

Watson,

I see you are into your BIG, BOLD and COLOR is some how more real and accurate sham again ...

Any conductors identified as Class 2 are deemed part of a Class 2 as those conductors are required to be re-identified as other than Class 2 if they are not being used for Class 2 circuits - thus, if thermostat cable, which is identified as being Class 2 on the outer jacket, is used, then the circuit is deemed to be Class 2 until proven otherwise, and, when proven otherwise, the Class 2 cable is required to be re-identified as not being Class 2.

Think of it as using Class 2 labeled transformer on circuit which is not a Class 2 circuit and you and Roland stating that it is therefore a Class 2 circuit ... the Class 2 identified cable is considered as Class 2 unless it has been re-identified as being other than Class 2.

The code does not allow Class 2 identified wiring to be used in other than Class 2 circuits. There IS more to it than just having a Class 2 identified transformer.

Jerry, would you state your NEC references for all of your declarations above? I don't believe any of it has NEC support. Thanks

Originally Posted by Roland Miller

Jerry, would you state your NEC references for all of your declarations above? I don't believe any of it has NEC support. Thanks

725.25 Abandoned Cables.
- Unless the cables have been terminated and/or tagged as for future use, abandoned Class 2, Class 3 and PLTC cables shall be removed where accessible.

725.30 Class 1, Class 2 and Class 3 Circuit Identification.
- These shall be identified at terminals and junctions.

725.124 Circuit Marking

725.130(A) Exception 2. Class 2 and Class 3 circuits shall be permitted to be reclassified and installed as Class 1 circuits if class 2 ad Class 3 markings required in 725.124 are eliminated and the entire circuit is installed using the wiring methods and materials in accordance with Part II, Class 1 circuits.
- Informational note: Class 2 and Class 3 circuits reclassified as Class 1 circuits are no longer Class 2 or Class 3 circuits, regardless of the continued connection to a Class 2 or Class 3 power source.

Originally Posted by Jerry Peck

The best no brainer way is to simply look at the wiring - most will use thermostat cable, which is going to be labeled as Class 2 wiring. If the circuit contains ANY Class 2 wiring then the entire circuit is a Class 2 circuit.

Originally Posted by Jerry Peck

Watson,

I see you are into your BIG, BOLD and COLOR is some how more real and accurate sham again ...

Any conductors identified as Class 2 are deemed part of a Class 2 as those conductors are required to be re-identified as other than Class 2 if they are not being used for Class 2 circuits - thus, if thermostat cable, which is identified as being Class 2 on the outer jacket, is used, then the circuit is deemed to be Class 2 until proven otherwise, and, when proven otherwise, the Class 2 cable is required to be re-identified as not being Class 2.

Think of it as using Class 2 labeled transformer on circuit which is not a Class 2 circuit and you and Roland stating that it is therefore a Class 2 circuit ... the Class 2 identified cable is considered as Class 2 unless it has been re-identified as being other than Class 2.

The code does not allow Class 2 identified wiring to be used in other than Class 2 circuits. There IS more to it than just having a Class 2 identified transformer.

Although 'interesting', falsely warped logic, the above does not support Peck's position, nor his rudeness. His further 'invention' as to what others have said in this discussion is completely baseless and similarly flawed, warped, and disingenuous. What WAS said is that WITHOUT the requisite Class 2 power SUPPLY it CANNOT "be" a Class 2 circuit.

If not supplied with a classified, listed, or Field Evaluated Class 2 power supply (which is NOT just a transformer, btw) it is NOT a Class 2 circuit, PERIOD.

It takes MORE than just the wiring method/type to classify a circuit! There is only ONE 'shamming' the discussion and his initials are J.P.

Another misnomer earlier in the discussion - regular standard household line voltage is not "high voltage", 'its all "low voltage"' less than 600V, 120/240, 50V, 30V, 24V, 12V; AC, DC, etc.

Originally Posted by H.G. Watson, Sr.

If not supplied with a classified, listed, or Field Evaluated Class 2 power supply (which is NOT just a transformer, btw) it is NOT a Class 2 circuit, PERIOD.

And ... JUST BECAUSE IT IS "supplied with a classified, listed, or Field Evaluated Class 2 power supply (which is NOT just a transformer, btw)" DOES NOT therefore make it a Class 2 or Class 3 circuit - or can you not read ... or maybe it is just that you don't bother to read ...

It takes MORE than just the wiring method/type to classify a circuit! There is only ONE 'shamming' the discussion and his initials are J.P.

And it takes MORE than just the supply to classify a circuit! There is only ONE 'shamming' the discussion and his initials are WATSON ... (gosh, I said "initials" and wrote out the last name ...

Another misnomer earlier in the discussion - regular standard household line voltage is not "high voltage", 'its all "low voltage"' less than 600V, 120/240, 50V, 30V, 24V, 12V; AC, DC, etc.

Actually, and yet another example of you saying that someone else is incorrect and you do it with an incorrect statement, the NEC does not define "low voltage" OR "HIGH VOLTAGE", thus you are incorrect in referring to " 'its all "low voltage"' less than 600V, 120/240, 50V, 30V, 24V, 12V; AC, DC, etc "

"High Voltage" is typically thought of as over a few thousand volts and up, such as found in transmission lines.

The NEC used 600 volts as a dividing line but does not define that as a dividing line between "low" and "high" voltage.

Typically, "low voltage" is considered to be 50 volts or less, sometimes even 30 volts or less; and "high voltage" is considered to be 13.7 kv (as but one example of a transmission voltage), but those who work with that may not even consider that to be "high voltage", they may well consider the high-voltage transmission lines to be "high voltage".

There is no set definition for "low voltage" or for "high voltage", so before you go around correcting others (in this case John) - get your facts straight ... wait ... you have never been able to do that ... what to heck am I thinking you may be capable of ... whatever it is I may be thinking, you are incapable of --- getting your facts straight!

Originally Posted by Jerry Peck

The best no brainer way is to simply look at the wiring - most will use thermostat cable, which is going to be labeled as Class 2 wiring. If the circuit contains ANY Class 2 wiring then the entire circuit is a Class 2 circuit.

I agree this meets the definition of class 2 "circuit". But it, by itself is not class 2 unless connected to a labeled class 2 transformer, then you can apply the requirements of NEC 725. See 725.121.

Jerry, you can actually install the class 2 circuit using any of the wiring methods defined in Chapter 1-4 of the NEC ( 725.130 (B) exception no. 2). It would make no economic sense to do this rather then use a cable. Also the cable isn't required to be "factory" label as Class 2. Only the field labeling is required as you have stated further on..

Originally Posted by Jerry Peck

And ... JUST BECAUSE IT IS "supplied with a classified, listed, or Field Evaluated Class 2 power supply (which is NOT just a transformer, btw)" DOES NOT therefore make it a Class 2 or Class 3 circuit - or can you not read ... or maybe it is just that you don't bother to read ...



And it takes MORE than just the supply to classify a circuit! There is only ONE 'shamming' the discussion and his initials are WATSON ... (gosh, I said "initials" and wrote out the last name ...



Actually, and yet another example of you saying that someone else is incorrect and you do it with an incorrect statement, the NEC does not define "low voltage" OR "HIGH VOLTAGE", thus you are incorrect in referring to " 'its all "low voltage"' less than 600V, 120/240, 50V, 30V, 24V, 12V; AC, DC, etc "

"High Voltage" is typically thought of as over a few thousand volts and up, such as found in transmission lines.

The NEC used 600 volts as a dividing line but does not define that as a dividing line between "low" and "high" voltage.

Typically, "low voltage" is considered to be 50 volts or less, sometimes even 30 volts or less; and "high voltage" is considered to be 13.7 kv (as but one example of a transmission voltage), but those who work with that may not even consider that to be "high voltage", they may well consider the high-voltage transmission lines to be "high voltage".

There is no set definition for "low voltage" or for "high voltage", so before you go around correcting others (in this case John) - get your facts straight ... wait ... you have never been able to do that ... what to heck am I thinking you may be capable of ... whatever it is I may be thinking, you are incapable of --- getting your facts straight!

?????!!!

Reference leg volts to ground at or less than 300V to ground, the NEC does so categorize. It also envokes OTHER NFPA 'code' documents by reference and incorporation. The NEC does NOT cover transmission "lines" nor infrastructure.

"Low", "medium" and "high".

Regardless, your commentary and derisiveness are both uncalled for and citations incorrectly applied and are false argument.

The Classification basis of a Class 1, Class 2, etc. circuit are BASED upon the power supply and the characteristics of the limited power(ed) circuit, the wiring method employed is NOT definitive of the classification, the wiring method is ancillary to the classification of a power-limited classified circuit.

The OP's "Main Panel" was not defined, It was not defined as a service panel or service equipment.

As a part of the listing and labeling, limitations, ratings, temperature limitations (terminals, wiring - conductors, insulation, AIC ratings, breakers etc.) are required to be maintained for the application. Generally, power-limited circuit wiring does not employ the insulation, wiring, nor amperage ratings at minimum required values to be legally present in a 'load center' (i.e. door bell transformers) under old rules spacially, etc. and newer standards for safety (listing requirements) for 'load centers' as well as the 'rest' of a particular NEC edition an application of same to or in the 'main panel' was manufactured under.

Originally Posted by H.G. Watson, Sr.

Regardless, your commentary and derisiveness are both uncalled for and citations incorrectly applied and are false argument.

Precisely what we think of your comments, belittling of others, and incorrect information which you somehow seem to think can be made less incorrect by using big, bold, color text ... needless to say (well, I am saying it, so I guess is it not "needless to say" - saying it IS needed) ... making incorrect information bigger, bolder, even red or blue, does not make it less incorrect.

Your comments on this site are usually boorish and indicate you think you are some god-like creature whom everyone is beneath and should obey you and do as you say.

Sorry to be the one to have to point out the obvious (at least obvious to all or most others) ... you are not who you think you are with regard to this site and its members.