Buzzer and bell transformer

[hhsting]

I have buzzer and bell transformer 120VAC to 24VAC. Below is what engineer sent.

I have following questions:

1. Would that require system bonding jumper? I am not sure if NEC 2017 Article 250.30 applies or not.

2. Would that require grounding electrode conductor secondary?

3. Would that require secondary overcurrent protection?

 

[augie47]

It would depend on the specific details of "T-1" but normally "No" to all your questions.

 

[busman]

I have buzzer and bell transformer 120VAC to 24VAC. Below is what engineer sent.

I have following questions:

1. Would that require system bonding jumper? I am not sure if NEC 2017 Article 250.30 applies or not.

2. Would that require grounding electrode conductor secondary?

3. Would that require secondary overcurrent protection?

The rules for Power Limited Circuits are very different. Please check Article 725.

 

[hhsting]

The rules for Power Limited Circuits are very different. Please check Article 725.

I don’t follow how is Article 725 related to grounding and bonding of the transformer?

 

[rc/retired]

This is no different than a standard doorbell transformer.120 volts go in, 24 volts come out.
Chances are that the transformer will be installed on a metal box and will be "grounded" by proxy.

Ron

 

[hhsting]

This is no different than a standard doorbell transformer.120 volts go in, 24 volts come out.
Chances are that the transformer will be installed on a metal box and will be "grounded" by proxy.

Ron

Yes it used for bell or buzz type application.

Anything in NEC 2017 that says grounding electrode conductor and system bonding jumper not required for these types of transformer?

 

[hillbilly1]

It won’t hurt anything bonding it, usually just a bond jumper wire. You don’t have to use a grounding electrode if that’s your question.

 

[hhsting]

It won’t hurt anything bonding it, usually just a bond jumper wire. You don’t have to use a grounding electrode if that’s your question.

I don’t see where in NEC 2017 it says bonding jumper is required or not required for this type
of transformer? I got it wouldn’t hurt

 

[rc/retired]

Yes it used for bell or buzz type application.

Anything in NEC 2017 that says grounding electrode conductor and system bonding jumper not required for these types of transformer?

In this application, no special bonding is required.
I, like every other electrician on this site have installed hundreds of these.
As an inspector, I've inspected hundreds.
You are good to go!

Ron

 

[hillbilly1]

Usually it’s most common on energy management systems that use ground as a reference point. The engineer probably just pasted it from that .

 

[tom baker]

Look in Art 250 rules on SDS. There is exception on small transformers

 

[hhsting]

Look in Art 250 rules on SDS. There is exception on small transformers

This one?

Sent from my iPhone using Tapatalk

 

[augie47]

Yes and 250.20(A)

 

[hhsting]

Yes and 250.20(A)

Transformer is 100va primary 120V and secondary 24V used for door bell or buzzer application in cash registers or front of door.

So according 250.30(A)(1) exception 3 system bonding jumper is required but then 250.20(A) system bonding jumper is not required?

 

[tortuga]

250.20(A) says its not required to be grounded, so its permitted to be an ungrounded system.
250.30(A) applies to grounded systems.

 

[don_resqcapt19]

Yes it used for bell or buzz type application.

Anything in NEC 2017 that says grounding electrode conductor and system bonding jumper not required for these types of transformer?

Start with 250.20(A) that tells you the 24 volt system is not required to be a grounded system. If it is not a grounded system, there cannot be a system bonding jumper as that only exists on grounded systems.

 

[tortuga]

I guess if you really want to over think things technically 250.30(B) would apply to a ungrounded class 2 xformer, but then 251.121 Exception permits a wire type branch circuit equipment ground.

 

[wwhitney]

Start with 250.20(A) that tells you the 24 volt system is not required to be a grounded system. If it is not a grounded system, there cannot be a system bonding jumper as that only exists on grounded systems.

But 250.20(A) allows it to be a grounded system, and the schematic posted shows a grounded secondary.

250.30(A)(1) Exception 3 then provides relief on the System Bonding Jumper size in this application. Does anything provide relief for a GEC connection for such an installation?

Cheers, Wayne

 

[Electromatic]

Does anything provide relief for a GEC connection for such an installation?

250.30(A)(4) Exception 3

 

[rc/retired]

In this application, no special bonding is required.
I, like every other electrician on this site have installed hundreds of these.
As an inspector, I've inspected hundreds.
You are good to go!

Ron

Apparently I was wrong!

Ron