Equipment Grounding Conductors

[Brandon Loyd]

With a transformer, is it required to pull in ground wires with your primary and secondary wire and bond them to the case? Or is the conduit still considered your EGC as long as it makes a good bond with the XFMR case (i.e. not installed in concentric knockouts or in reducing bushings)?

 

[augie47]

For the primary, any equipment ground listed in 250.118 is acceptable including listed conduits.
If your transformer has a ground point (XO, etc) the NEC requires a system bonding jumper that complies with 250.30(A)(1)

 

[roger]

If the raceway is recognized as an EGC per 250.118 and all other criteria is met there is no need for a wire conductor.

Roger

 

[jwelectric]

Remember that a flexible metal raceway must have overcurrent in front therefore a flexible conduit would require a conductor.

(5) Listed flexible metal conduit meeting all the following conditions:
b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.

(6) Listed liquidtight flexible metal conduit meeting all the following conditions:
b. For metric designators 12 through 16 (trade sizes 3⁄8 through 1⁄2), the circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
c. For metric designators 21 through 35 (trade sizes 3⁄4 through 11⁄4), the circuit conductors contained in the conduit are protected by overcurrent devices rated not more than 60 amperes and there is no flexible metal conduit, flexible metallic tubing, or liquidtight flexible metal conduit in trade sizes metric designators 12 through 16 (trade sizes 3⁄8 through 1⁄2) in the grounding path.