mixing neutrals of different systems

[stew]

Just a hypothetical possibly dumb question. What if you had a 480/227 volt system in a building supplying 277 volt lightnig. Then attached to that system you haver a step down transformer to feed a 120/208 volt system for 120 volt loads. Down line say the 277 volt system and the 120 volt system end up in the same j box . The neutrals of both systems get tied together in this j box. What would be the result?

 

[480sparky]

What is known in the astronomical world as a singularity would be produced. This would spawn the largest black hole in the history of the universe. All matter would be sucked in and summarily disappear.

NBC would come to their senses about the late-night talk show situation, and Obama's approval rating would shoot up to 98%.

WalMart would file for bankruptcy, and all homeowners would cease to perform their own electrical work.


But beyond that, I'd say nothing earth-shattering (electrically) would happen.

 

[mivey]

But beyond that, I'd say nothing earth-shattering (electrically) would happen.

Maybe not earth shattering but maybe some parallel paths, some unintentional currents, maybe some tripped ground relays...

 

[nakulak]

of course, if something unusual happened (let's say that the 277 neutral became loose or open near the panel) then you would have a 120 ckt that was energized with 277

 

[480sparky]

of course, if something unusual happened (let's say that the 277 neutral became loose or open near the panel) then you would have a 120 ckt that was energized with 277

Then you'd have the smoke escape from the equiment and stuff connected to the circuit.

Once you fix the problem, you go out and buy new stuff with fresh smoke in it.

 

[nakulak]

or worse, cause after the smoke came out, the electrician might cut off all the 120 breakers and foolishly thinking the power was off in the box, find himself hooked to a hot 277 ckt

 

[augie47]

Most likely, with both neutrals bonded to grounding electrodes, they are already connected.

 

[480sparky]

Most likely, with both neutrals bonded to grounding electrodes, they are already connected.

Oh, sure! Spoil everything with the obvious!

 

[Jim W in Tampa]

High chance you might overload a neutral and no guess what harmonics would do. And you likely will be unemployed

 

[augie47]

your predictions were beginning to scare me

 

[RETRAINDAILY]

Fired!
That is Y 277v is Grey and 120v is white.

 

[iwire]

Fired!
That is Y 277v is Grey and 120v is white.

That is not a code requirement, that is a choice.

 

[RETRAINDAILY]

That is not a code requirement, that is a choice.

200.6 doesn't say that? it doesn't say any thing about what color in what system but your choices are limited.
the building I am currently working someone had installed a 277v. lighting system in a addition to the building it is all black, red,blue with a white.
IMO bad choice all the way around.

 

[brian john]

You would end up with ground current as current form each load returns to the source through the neutral ground bond.