Do these transformers need to be bonded and grounded?

[powerpower]

Hello World!

Hoping someone can provide clarifications on whether I need to bond and ground a "desktop" style step-down isolation transformer. Here's the transformer I'm interested in using to provide 120V to equipment when traveling overseas at 240V locations: http://www.hammondmfg.com/289T.htm

NEC seems to require bonding and grounding of secondary for transformers rated >1kVA. If I have the 1.5kVA model from the aforementioned transformer series, am I then required to bond my output neutral to ground, and also run a separately derived ground to the same bonding point?

Thanks.

 

[rlundsrud]

No, just plug it in. It is a UL listed device and is pretty much plug and play.

 

[powerpower]

when does the NEC's requirements for bonding and grounding apply? does the NEC provide an exception for devices like these?

 

[jumper]

when does the NEC's requirements for bonding and grounding apply? does the NEC provide an exception for devices like these?

Look at the schematic in your link. The bonding and grounding is already done in the internal wiring.

 

[SceneryDriver]

Look at the schematic in your link. The bonding and grounding is already done in the internal wiring.

Interestingly enough, the secondary neutral is not bonded to the incoming ground wire. The transformer's output is floating with reference to ground, even though ground is provided at the 120VAC receptacles.


SceneryDriver

 

[powerpower]

Look at the schematic in your link. The bonding and grounding is already done in the internal wiring.

The core is bonded to ground, but the output neutral is not. The secondary neutral is floating. I looked at a few other manufacturers, and it seems like none of these are made with the output neutral bonded to chassis/ground.

 

[powerpower]

Hello World!

Hoping someone can provide clarifications on whether I need to bond and ground a "desktop" style step-down isolation transformer. Here's the transformer I'm interested in using to provide 120V to equipment when traveling overseas at 240V locations: http://www.hammondmfg.com/289T.htm

NEC seems to require bonding and grounding of secondary for transformers rated >1kVA. If I have the 1.5kVA model from the aforementioned transformer series, am I then required to bond my output neutral to ground, and also run a separately derived ground to the same bonding point?

Thanks.

If I'm applying the NEC correctly, Article 250.20(B) would require that these transformers be grounded (to have a SBJ and SDG). Is this true? Is there an exception to this rule for these types of travel transformers?

 

[just the cowboy]

isulation = non grounded

isulation = non grounded

When we used these in machine control it was FOR isulation. If they bond them they are not isulation xformer any more.

 

[powerpower]

When we used these in machine control it was FOR isulation. If they bond them they are not isulation xformer any more.

These won't be used for control circuits. These will be used to supply power to 120V equipment when traveling to 240V locations. Isolation type step-down transformers are preferred over autotransformers for the best protection. For example, with an autotransformer, if the winding section where the output is tapped gets damaged (failed open), the output voltage can rise to input level voltage and damage the equipment.