New one for me!

Originally Posted By: jpeck
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The low voltage transformer will (most likely will, anyway) a threaded hub which gets inserted through a knock out and is held in place with a lock nut, putting the 120 volt supplies in the panel (which, if not careful, can create its own problems) and the transformer and low voltage side outside the panel.



Jerry Peck


South Florida

Originally Posted By: dvalley
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Scott,


I never mentioned attaching this to the panel itself, I quoted "installed onto the exterior of the SE panel". You have a good point about the sheet metal screws. Not good.
I do see these transformers attached directly to the side of the panel most of the time. I don't call them out.

About sugarcoating or soft selling this matter... Good point, again. Lets get them all removed.![](upload://aJizSi1EuOt25dL2FR4AHt5AZ3G.gif)


--
David Valley
MAB Member

Massachusetts Certified Home Inspections
http://www.masscertified.com

"Some cause happiness wherever they go; others, whenever they go."

Originally Posted By: Blaine Wiley
This post was automatically imported from our archived forum.



In general, the standard installations I have seen over the years have been either on the side of the panel, as Jerry said, or on the outside of a metal junction box either on a basement or garage light.


Technically, no low voltage wriring should be inside a main service panel, and when I find it I do write it up for further evaluation/correction by a qualified licensed sparky.

I posted this pic just cause I thought y'all would find it funny, still being in the box! ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif) ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif) ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

Blaine


Originally Posted By: roconnor
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Scott and Jerry … let me play devils advocate here. You are both indicating that just the presence of a doorbell transformer in a service panel is a code violation.


I dont see where the NEC or UL panelboard listing/labeling standard clearly states that transformers or low voltage wiring can not be installed in a service panel.

It's not good practice, but assuming the equipment is listed for that, what code/section does this violate?


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Blaine Wiley
This post was automatically imported from our archived forum.



How about telephone wires? I found them running through a panel yesterday! That could be a shocking conversation icon_lol.gif icon_lol.gif


Blaine


Originally Posted By: rking
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I have the solution to this whole thread icon_cool.gif


Why not just inform the clients to get in touch with the times and install wireless door chimes ???



Muskoka Home Inspections


“Wisdom is the Anticipation of the Consequences”


Steering Committee Member At Large

Originally Posted By: Mike Parks
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Robert


"It's not good practice, but assuming the equipment is listed for that, what code/section does this violate?"

Let's start with 370.17(A).

LOL

Mike P.


Originally Posted By: rking
This post was automatically imported from our archived forum.



I knew there had to be something there for it icon_twisted.gif


Ah heck, I do not quote codes anyway! But…



Muskoka Home Inspections


“Wisdom is the Anticipation of the Consequences”


Steering Committee Member At Large

Originally Posted By: Bob Badger
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I can give you some codes for this transformer in a panel.


1)Doorbell transformers are a class 2 circuit.

Quote:
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).

(B) Separated by Barriers. Class 2 and Class 3 circuits shall be permitted to be installed together with Class 1, non?power-limited fire alarm and medium power network-powered broadband communications circuits where they are separated by a barrier.

(C) Raceways Within Enclosures. In enclosures, Class 2 and Class 3 circuits shall be permitted to be installed in a raceway to separate them from Class 1, non?power-limited fire alarm and medium power network-powered broadband communications circuits.

(D) Associated Systems Within Enclosures. Class 2 and Class 3 circuit conductors in compartments, enclosures, device boxes, outlet boxes, or similar fittings shall be permitted to be installed with electric light, power, Class 1, non?power-limited fire alarm, and medium power network-powered broadband communications circuits where they are introduced solely to connect the equipment connected to Class 2 and Class 3 circuits, and where (1) or (2) applies:

(1) The electric light, power, Class 1, non?power-limited fire alarm, and medium power network-powered broadband communications circuit conductors are routed to maintain a minimum of 6 mm (0.25 in.) separation from the conductors and cables of Class 2 and Class 3 circuits.

(2) The circuit conductors operate at 150 volts or less to ground and also comply with one of the following:

a. The Class 2 and Class 3 circuits are installed using Type CL3, CL3R, or CL3P or permitted substitute cables, provided these Class 3 cable conductors extending beyond the jacket are separated by a minimum of 6 mm (0.25 in.) or by a nonconductive sleeve or nonconductive barrier from all other conductors.
b. The Class 2 and Class 3 circuit conductors are installed as a Class 1 circuit in accordance with 725.21.

(E) Enclosures with Single Opening. Class 2 and Class 3 circuit conductors entering compartments, enclosures, device boxes, outlet boxes, or similar fittings shall be permitted to be installed with Class 1, non?power-limited fire alarm and medium power network-powered broadband communications circuits where they are introduced solely to connect the equipment connected to Class 2 and Class 3 circuits. Where Class 2 and Class 3 circuit conductors must enter an enclosure that is provided with a single opening, they shall be permitted to enter through a single fitting (such as a tee), provided the conductors are separated from the conductors of the other circuits by a continuous and firmly fixed nonconductor, such as flexible tubing.


This goes on to sections F, G, H, I, and J but have to do with hoist-ways, manholes etc.

Are you bored yet? ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

2)You also have to consider panel fill, on a newer panel space is usually plentiful, on an older panel this could be a problem.


Quote:
312.8 Enclosures for Switches or Overcurrent Devices.
Enclosures for switches or overcurrent devices shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to other switches or overcurrent devices, unless adequate space for this purpose is provided. The conductors shall not fill the wiring space at any cross section to more than 40 percent of the cross-sectional area of the space, and the conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space.


I know you guys are quite familiar with 110.3(B).

There are not many instructions that come with a doorbell transformer but what is shown is the unit mounts to the outside of any enclosure by the use of a threaded hub or a bent tab with a set screw.

All the new doorbell transformers have thermal protectors in them, it is possible mounting them (or even worse laying them, when mounted the enclosure works like a heat sink) in an enclosure would cause the thermal to cut out.

I have been told by electricians that wire houses (I do commercial work) that installing door bell transformers in hot spaces like attics while code compliant, can lead to call backs when the thermals cut out.

For what it's worth this is also a regular topic on the electricians bulletin boards, usually comes up when the electrical inspector fails a job for the transformer in the panel.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



… Although you should not quote code sections, building codes are extremely useful tools for an HI, who should be familiar with at least the basics.


On this issue I would look to the codes to help clarify if the transformer in the panel would fall under "defect/maintenance" since it is at least poor practice, or perhaps it really crosses that line, and should be red flagged as a "safety hazard".

See where I am going with this.


Jerry ... Okay, thats a start ... looks like a 1999 NEC reference. But thats out on loan ... can you trans to 2002 ... ![icon_redface.gif](upload://f7DX2EWhmUfsDapWaYT3oJHMCj1.gif)

I seem to recall it's a pretty vague section though ... anything more concrete.


Bob (aka iwire) ... Welcome to the board ... glad to have your knowledge here too. I enjoy your posts over on MH's board when I have the time to visit ... very practical and helpful. Thanks for you input here.

Now, about this sticky transformer issue. No, I'm not bored yet ... lol. While I agree it's at least poor practice (have heard the same complaints), is it really a blatant code violation that would indicate it's a significant safety hazard that could cause a fire or shock?

2002 NEC 725.55(D) seems to permit the Class 2 circuits in enclosures/compartments (with adequate clearances), but the "introduced solely to connect the equipment" part is not crystal clear ...


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



roconnor wrote:
Bob (aka iwire) ... Welcome to the board ... glad to have your knowledge here too. I enjoy your posts over on MH's board when I have the time to visit ... very practical and helpful. Thanks for you input here.


Thank you for the kind words, someone steered me over to this forum and I found it interesting.

When HIs ask questions on some of the electrical forums they can sometimes get a little beat up. ![icon_sad.gif](upload://nMBtKsE7kuDHGvTX96IWpBt1rTb.gif)

This IMO is usually not right, (some electricians get a little beat up when they deserve it) we all have a job to do and an HI trying to find the true NEC answer should be commended for not shooting from the hip.

The NEC is a tough subject add to that you are trying to deal with many other codes.

So ask away I will try to give you code facts mixed with some opinions.

This transformer in a panel is a good example of no absolute answer.

roconnor wrote:
Now, about this sticky transformer issue. No, I'm not bored yet ... lol. While I agree it's at least poor practice (have heard the same complaints), is it really a blatant code violation that would indicate it's a significant safety hazard that could cause a fire or shock?


IMO no it is not a significant safety issue.

I agree with you it is a poor practice, one thing we did not touch on is the voltage rating of the conductors used on the load side of the transformer.

Quote:
300.3(C) Conductors of Different Systems.
(1) 600 Volts, Nominal, or Less.
Conductors of circuits rated 600 volts, nominal, or less, ac circuits, and dc circuits shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.


roconnor wrote:
2002 NEC 725.55(D) seems to permit the Class 2 circuits in enclosures/compartments (with adequate clearances), but the "introduced solely to connect the equipment" part is not crystal clear ...


Yes, clear as mud, I would not think twice of a transformer installed in a motor controller, it would be wired on both sides with 600 volt rated conductors.

In that case it is accepted practice.

So Robert I think we are on the page, while I would not write this up as a major issue, IMO it would be worth putting down as poor practice.

Bob


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



By the way here is 1999 NEC 370.17(A)


Quote:
370-17. Conductors Entering Boxes, Conduit Bodies, or Fittings
Conductors entering boxes, conduit bodies, or fittings shall be protected from abrasion and shall comply with (a) through (d).

(a) Openings to Be Closed. Openings through which conductors enter shall be adequately closed.


![icon_smile.gif](upload://b6iczyK1ETUUqRUc4PAkX83GF2O.gif)


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



Bob,


Thanks for the info and your input. Very much appreciated ... ![eusa_clap.gif](upload://vwXJP6EroRUgatgS660IOyuD5XK.gif)

Others here, and myself, have posted issues/comments on MH's board and have not had any real bashings (yet) ... ... But we are mindful that we are not electricians or electrical experts, and don't come off like we know better or cross the lines of practice ... just like engineers get sensitive about a HI crossing the "observe and report" line into "evaluation".

That 370-17(a) reference is what I though ... would be 314.17(A) under 2002 NEC. Pretty vague, so I thought Jerry might be talking about another section.

300.3(C) seems to also permit the transformer wiring as long as the wire insulation has adequate rating. Not so sure about that one ... is that the section electrical code officials quote to write up transformers in panels on new installs? Does that apply if the Class-2 wire has the 1/4" clearance required by 725.55(D)? Even so, could an existing install be "grandfathered" under older codes which is why you come across them.

So far, I am still with doorbell transformers/wiring in an existing panel only being "poor practice" (assuming adequate clearances) and maybe being written up as a "concern/maintenance" item, and not a "safety hazard".


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Blaine Wiley
This post was automatically imported from our archived forum.



And may I add to Robert’s question,


How about the low voltage line leading out across the high voltage lines, and laying on the the buss bars. Is that incorrect or a safety hazard also?

Thank you,
Blaine


Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



bwiley wrote:
How about the low voltage line leading out across the high voltage lines, and laying on the the buss bars. Is that incorrect or a safety hazard also?


Hi Blaine sorry not to get back to this sooner.

It all depends on the voltage rating of the wire used.

Most times the wire used for door bell is not rated at all if this is the case the wires can not be in the same enclosure or conduit without some special precautions and laying against bus bars is not one of the precautions.

If the wire used is rated for 300 or 600 volts it could be in the panel anywhere, having it touch a buss bar is not a violation that I am aware of.

But IMO is a poor practice for any wires.

The basic rule for conductors of different voltages occupying the same space is this one.

Quote:
300.3(C) Conductors of Different Systems.
(1) 600 Volts, Nominal, or Less.
Conductors of circuits rated 600 volts, nominal, or less, ac circuits, and dc circuits shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.


An important thing to note is they say "maximum circuit voltage applied to any conductor"

In a dwelling unit this would be 240 or maybe 208 volts.

Other code articles talk about voltage to ground which of course in a dwelling unit will be 120 volts.

Most of the buildings I work on will have 480/277 panels and 208/120 panels, we often mix the voltages in one conduit but all the conductors will need to rated 600 volts.

By the way, typical NM (romex) is 600 volt rated and we will use it for 480 circuits.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



… from the original pic, it looks like the low voltage doorbell wiring goes from the trans up under the hot and then under the neutral/ground wires, and out the top.


It doesnt seem to cross the neutral buss (maybe another panel?), and it might even have the 1/4" clear required by NEC 725.55(D).

Also, there appears to be plenty of space in the panel, so I am curious if there were any reported problems with the doorbell that would indicate overheating of the transformer.

Bob ... If the low voltage wire insulation is not rated for at least 240V there seems to be a conflict between 300.3(C) and 725.55(D). But Article 725 contains more specific requirements, and therefore would apply (also see 725.1 and the FPN which states Article 725 are alternate requirements to Chapters 1-4).

Therefore with 1/4" clear on the Class-2 wires (easy to get, if not there now), and the fact that the Class-2 wires are there "solely to connect the equipment" for the wires, I still don't see any code sections that install would violate.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



roconnor wrote:
[
Bob ... If the low voltage wire insulation is not rated for at least 240V there seems to be a conflict between 300.3(C) and 725.55(D). But Article 725 contains more specific requirements, and therefore would apply (also see 725.1 and the FPN which states Article 725 are alternate requirements to Chapters 1-4).


Conflict ...no way. ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

The spacing requirements where the "special precautions" I was talking about and of course you can only do this spacing in an enclosure (which is what Blaine was talking about) not in conduit.

This time the NEC actually explains away the conflict, with another code article.

Quote:
90.3 Code Arrangement.
This Code is divided into the introduction and nine chapters, as shown in Figure 90.3. Chapters 1, 2, 3, and 4 apply generally; Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions. These latter chapters supplement or modify the general rules. Chapters 1 through 4 apply except as amended by Chapters 5, 6, and 7 for the particular conditions.
Chapter 8 covers communications systems and is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8.
Chapter 9 consists of tables.
Annexes are not part of the requirements of this Code but are included for informational purposes only.


So if you meet the conditions of 725 you can forget about 300.3(C) as far as enclosures.

Somewhere there is something about combustibles in electric equipment that would make the cardboard box a violation too, I just can not find it right now.


Back to 725.55 "where they are introduced solely to connect the equipment connected to Class 2 and Class 3 circuits"

This is a tough one to pin down. ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

I will stick with 110.3(B) as the instructions most times show this type of transformer is mounted externally to any enclosure. ![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

By the way, for anyone using the code book FPNs (Fine Print Notes) are not code and are not to be enforced.



--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



Bob Badger wrote:
Back to 725.55 "where they are introduced solely to connect the equipment connected to Class 2 and Class 3 circuits"


The way I read that, it means the Class-2 wires can only be there to connect to the transformer (aka the "equipment"). Blaine mentioned a different panel where telephone wires ran through a panel, and therefore would not meet that exception and would be an issue.

Bob Badger wrote:
Somewhere there is something about combustibles in electric equipment that would make the cardboard box a violation too, I just can not find it right now.


Good point ... I will have to take a look today between snowball fights with my kids ... lol. Maybe that is in the UL panelboard listing/labeling standard as required by 110.3(B).

But I think we are on the same page that the transformer inside the panel is still only a "concern" that a homeowner may want to have an electrician check out and possibly move outside the panel.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.



roconnor wrote:

But I think we are on the same page that the transformer inside the panel is still only a "concern" that a homeowner may want to have an electrician check out and possibly move outside the panel.


Yes ![icon_biggrin.gif](upload://iKNGSw3qcRIEmXySa8gItY6Gczg.gif)

I know I see and I have no doubt the HIs see things much worse then this.

Wrong overcurrent protection, no grounds, copper to aluminum connections done wrong, etc.

Take Care and good talking to you.



--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: JIM WALKER
This post was automatically imported from our archived forum.



The transformer in the panel is a very serious problem,should the wires ever rub thru to a 120 volt line someone standing in the rain ringing your bell might never get inside your door.


Most transformers state NOT FOR US IN ATTICS.


Get them out of the panel,you are hired to find things like this.The cost to fix doesn’t come out of your pocket.It is flat out a violation.



JIM WALKER


Tampa FL.


ELECTRICJIMW@AOL.COM