12v and 120v neutral Question

[acor]

Can a 12v neutral and a 120v neutral or ground be together on a bus bar?
My 48v battery won't turn on when I have both on but works when one or the other is one.
I do have a converter for the battery to 12v appliances.

 

[timselectric]

I assume that you are talking about the battery negatives?
And the 120vac neutral.
We're going to need more information about your systems.
Mobile or stationary? And what equipment do you have? How is everything connected?

 

[Rednecktek]

12v is typically DC and 120v is AC, so two different things. In DC there is Positive and Negative, no neutral. Likewise in AC there is Hot and there is Neutral, but no Positive or Negative.

I can't think of any situation where you'd want your AC wiring connected to the DC bus, that's bad.

 

[mikefitz]

Can a 12v neutral and a 120v neutral or ground be together on a bus bar?

Yes it's a reference point for the DC negative and the AC neutral and AC ground

think of any situation where you'd want your AC wiring connected to the DC bus , that's bad.

In a RV, metal box or steel boat, AC neutral and ground are bonded to metal for safety. DC negative is also bonded to metal.
Why is this bad?

 

[Rednecktek]

In a RV, metal box or steel boat, AC neutral and ground are bonded to metal for safety. DC negative is also bonded to metal.
Why is this bad?

Every ship I've worked on in the last 15 years has been built to NOT have the AC connecting to the hull, that's a ground and my job to make it stop happening as the ships electrician. The few RV systems I've worked on didn't have the AC grounded to the frame either, it was always floating. Pumping 120v current into a battery bank just seems like a horrible idea to me.

 

[Checkthisout]

Can a 12v neutral and a 120v neutral or ground be together on a bus bar?
My 48v battery won't turn on when I have both on but works when one or the other is one.
I do have a converter for the battery to 12v appliances.

No. Do not bond a/c neutral to DC battery negative.

 

[mikefitz]

Every ship

Sorry about the DC on a steel vessel, yes, a seperate negative isolated from hull.

For AC shore power either an isolation transformer or galvanic isolator is normal in pleasure craft in Europe

For RV instalation compliance to regulations In UK and Europe, shore power protective earth connects to frame / vehicle metal, the neutral bond is provided by the shore power outlet.
Any permanent battery powered inverter, acting as stand alone, needs neutral bond and protective earth bond to frame/ metal with RCD protection. House battery negative is connected to frame/ metal.
This is enforced in some countries when the vehicle has annual or bi annual inspection. Always required where its a commercial operation, example rental and mobile food outlet. In UK all professional built RV conform to regulations. Some insurance providers insist on an inspection report.

Mike