Bootleg Ground, Built that Way

[Mike Furlan]

I am looking at a 50 year old Westinghouse power cart, 480V, 3P, 60A that supplies 120V, 208V and 480V power.

Several of the 120V receptacles were installed with bootleg grounds.

Is this allowed?

I would not think so, except that these receptacles were installed this way by the manufacturer, not some hack "electrician."

 

[iwire]

480 volt cart, 120 receptacle?

So there is a transformer creating a new neutral?

If so I would say it is no different then installing 120 volt receptacles on the outside of a service panel. Neutral and EGC are the same at that point.

 

[Mike Furlan]

480 volt cart, 120 receptacle?

So there is a transformer creating a new neutral?

If so I would say it is no different then installing 120 volt receptacles on the outside of a service panel. Neutral and EGC are the same at that point.

Yes there is a transformer.

Yes it is _exactly_ like installing a 120V receptacle on the outside of a service panel.

And yes the neutral and the EGC are the same at that point, they all run from the same bus in this device.

But all of the above is the same reasoning for bootleging a ground on a branch circuit too, isn't it?

What difference does it make, if you move that outlet from the immediate outside of a service panel to the other side of the room, wired the same way?

 

[wireguru]

do you have a picture of this power cart?

 

[jim dungar]

Yes there is a transformer.

Yes it is _exactly_ like installing a 120V receptacle on the outside of a service panel.

Is this a single 120V 2-wire transformer directly feeding a single 120V receptacle?

 

[Mike Furlan]

Yes, here are some pictures.

 

[Mike Furlan]

Is this a single 120V 2-wire transformer directly feeding a single 120V receptacle?

No the transformer supplies 208V 3P and 120V power.

 

[iwire]

What difference does it make, if you move that outlet from the immediate outside of a service panel to the other side of the room, wired the same way?

Code wise it makes all the difference.

In the case of this cart what would you have done with the recptacle EGC?

 

[Mike Furlan]

Code wise it makes all the difference.

In the case of this cart what would you have done with the recptacle EGC?

I would have run an extra wire to eliminate the bootleg wiring. (Hot, neutral and ground)

That also fixes the equipment grounding conductor identification violation of using a black wire as the EGC.

But that still leaves my question, is this device allowed as is?

And was it allowed per code 50 years ago when it was built?

 

[480sparky]

....And was it allowed per code 50 years ago when it was built?

Was/is the thing even required to be wired according to the code?

 

[Mike Furlan]

Was/is the thing even required to be wired according to the code?

Maybe not.

The main reason that I'm posting here in the NEC section is that all the components in this device are certainly covered in the NEC.

Is there ever a case in which a bootleg ground is allowed per the code?

 

[iwire]

I would have run an extra wire to eliminate the bootleg wiring. (Hot, neutral and ground)

To where? :smile:

Where would you run the EGC from the 120 volt recptacle to?

And was it allowed per code 50 years ago when it was built?

I see no reason that anything inside that unit would be coved by the NEC. No more then the inside of a range or dishwasher.

 

[iwire]

Is there ever a case in which a bootleg ground is allowed per the code?

The following have 'Bootleg' EGCs as much as the one in your example.

• A service.
  
• A separately derived system.
  
• A range.
  
• A dryer.
  
• Until 2008 a separate building or structure.

 

[Mike Furlan]

To where? :smile:

Where would you run the EGC from the 120 volt recptacle to?



I see no reason that anything inside that unit would be coved by the NEC. No more then the inside of a range or dishwasher.

I'd run a green wire back to the same bus that the neutral is connect to.

And this device is not like a range or dishwasher, more like a transformer or generator, items that are covered in the NEC.

 

[Mike Furlan]

The following have 'Bootleg' EGCs as much as the one in your example.

• A service.
  
• A separately derived system.
  
• A range.
  
• A dryer.
  
• Until 2008 a separate building or structure.

Well yes, "bootleg" to the extent that the ground and neutral are connected.

However I'm focusing just on the receptacle. Even though it is electrically equivalent to bootleg the ground, does the code allow one black wire to be used as both the neutral and ground?

 

[LarryFine]

Looking at the pic of the back of the receptacle, the enclosure itself would provide the EGC continuity.

However, it's possible that this connection IS the main bonding jumper.

As an assembly, the NEC probably has no jurisdiction. My portable genny is probably wired the same way.

 

[dbuckley]

There is a real safety question with these sorts of assemblies.

Is the neutral (and thus the bootleg ground) of the secondary of the transformer connected to the incoming neutral of the primary of the transformer? If so, then there is a potential situation. If the neutral of the supply becomes disconnected leaving the hot connected (not unknown given the sorts of abuse these things get) then the bootleg ground rises to the supply potential forming a real source of danger. Any tools with a 3 wire cord will have their body metallic parts live with reference to the real ground...

 

[iwire]

Is the neutral (and thus the bootleg ground) of the secondary of the transformer connected to the incoming neutral of the primary of the transformer? If so, then there is a potential situation. If the neutral of the supply becomes disconnected leaving the hot connected (not unknown given the sorts of abuse these things get) then the bootleg ground rises to the supply potential forming a real source of danger. Any tools with a 3 wire cord will have their body metallic parts live with reference to the real ground...

This is really do different then every service in the US.

If we lose the neutral connection back to the source there is a very good chance all bonded objects will be at a raised potential in relation to earth.

 

[Mike Furlan]

There is a real safety question with these sorts of assemblies.

Is the neutral (and thus the bootleg ground) of the secondary of the transformer connected to the incoming neutral of the primary of the transformer? If so, then there is a potential situation. If the neutral of the supply becomes disconnected leaving the hot connected (not unknown given the sorts of abuse these things get) then the bootleg ground rises to the supply potential forming a real source of danger. Any tools with a 3 wire cord will have their body metallic parts live with reference to the real ground...

There is no incoming neutral.

There is just 480 three phase with a grounding conductor.

Is your concern still valid?

 

[dbuckley]

This is really no different then every service in the US.

If we lose the neutral connection back to the source there is a very good chance all bonded objects will be at a raised potential in relation to earth.

Absolutely. But the key word there is "bonded" - when a home loses its neutral everything around you in the home is bonded, and it all rises to some potential, so there is no difference in potential between objects, so no shock risk inside the home assuming everything really is bonded. Hence the term "equipotential".

Its all a bit different on a construction site or on the factory floor where these things typically are used. You have your drill in one hand, with its body (because of neutral failure) at phase potential, and lean on a steel beam that is properly grounded, and you get the ouch treatment. Construction sites are much wetter places than homes or offices so tool bodies going live is a much bigger hazard. Wet shoes in muddy ground, wet socks, wet gloves, live tool body...

Its the failure to appreciate that the same wiring system in two different scenarios presents a whole different degree of risk is what the ultimate danger is here.