Transformer grounding

[JdoubleU]

Does a 120volt to 24volt transformer for the controls to a HVAC unit need to be grounded on the secondary side? If not then when would it need to grounded?

 

[Pierre C Belarge]

See:
250.20 Alternating-Current Systems to be Grounded.

(A) Alternating-Current Systems of Less Than 50 Volts.

Also take a look at 250.21 & .22

 

[LarryFine]

Does a 120volt to 24volt transformer for the controls to a HVAC unit need to be grounded on the secondary side? If not then when would it need to grounded?

The new HVAC systems I've seen for the last several years have had the 24v system grounded.

 

[boboelectric]

Sure helps when troulbleshooting.