Lighting Circuits Without Neutral

Consider the installation of a zig-zag transformer with which to provide a neutral.

You've missed out the most important detail. What is the line to line voltage?

Just out of interest why is the neutral isolated?

The line to line voltage is 230 V

the neutral is isolated since thats what the client wants :P

You can, but the Phase-phase voltage will be Sqrt(3) x 230 V for 230 V system. You can use 2 pc of lamp in series . one lamp will have only 200V. Incandescent and Energy saving lamp will work well, ES lamp best, Incand lamp slightly dimmer than on 230 V.

FL lamp or compact FL lamps with magnetic ballast may have start up problem.

Do encourage the original poster to use double-pole or triple-pole overload circuit breakers!

very simple: take three 100w single phase bulbs (of say 230V), connect them is star and connect each bulb to each phase (of say 415V) and leave neutral point in isolation... there you have done it.

100W bulbs are no longer available.

What does srikanthuk do about switching, isolation and overcurrent protection?

That works if the supply voltage = √3*bulb voltage. But he hasn't told us either voltage. If bulb voltage = supply voltage he can just connect between any 2 phases.

You do not need a neutral. Just choose the lights that are rated for the phase to phase voltage. It is a common installation in the US.

I'm going to take a different tactic here.

Just pick any two wires and connect them to your lighting fixtures. Don't worry about supply voltages, or fixture ratings. They will just get you confused. The engineers who designed the fixtures had to plan for unlicensed electricians using their product in random ways, so if you get anything wrong their protection circuitry should work. Make sure you try changing a lamp once this is installed.

Ok, enough with the absurdity response.

Yes, it is possible to make a lighting system without a neutral.

The question should be will a lighting system without a neutral meet the electrical wiring code for your location? I do not know. I do not know where this lighting system will be so I cannot tell you.

Professional installations use separate, to single phase transformer and breaker panel for light and general use. That normally is the code.

In your scheme you string up some light for, say 380 or 450V. The lightbulb voltages do not add up right. Then one day an unsuspecting electrician comes along, treats it as a normal 110V circuit, and get fried. What you think, who will be blamed?!? YOU.

If the source is Y or 4 wire delta there is a neutral. If not, then select fixtures that run on the available output. If that is not practical, then install a transformer that will give the desired voltage...Clintb

Yeah, great. One loose connection on the earth lead and the next person to touch something on it gets electrocuted. Brilliant suggestion.

That has to be on of the most stupid statements I've ever read on this board!

Not clear. Please elaborate how the Neutral is isolated.

Is your distribution in Delta " Δ" ?

or

"Y" without the 4th wire= N in your system.

What do you mean by distribution? Star or delta doesn't apply to the mains supply. Mains is 3 wires with a certain line-line voltage, and maybe a neutral. It's the rated voltage of the load compared with the supply voltage that determines how the load is connected.

Regards.

Star and Delta surely apply to mains supply distribution.

In your country like ours it is Star [Y] 3+1 RST+N and domestic distribution is

normally single Φ; Φ & N; R+N; S+N or T+N.

In Europe it is UVW and somewhere it may be ...

In USA it Δ delta; Φ + Center-tap of Φ;

But Isolted Neutral is not understood.

Can you explain please?

Welcome for related answer. !!!!!

I don't think star or delta is inherent in the mains supply. There are 3 phases with (in Europe) 400 volt between any 2. On a 3-phase motor, connection can be in star or delta depending on motor design, but if it's star it does not need a neutral as the star point is not connected to anything.

I agree a neutral is needed for single-phase (phase-neutral) use, but that doesn't mean the system is star. That's my take, somebody might disagree. The power company tries to share the single-phase loads between all 3 phases, so the current in the neutral to the transformer is small.

By isolated neutral I assume OP means there is no neutral wire in his mains lead, so single-phase operation is not possible, hence his question.

I think let the OP say what he means.

I have not seen any country which only supplies Φ to Φ domestic supply.

I have no more explanation.

Regards

This sounds like an industrial system. The most common non-residential service in the US is 480V 3-phase/3-wire supplied by a delta connected transformer bank. A delta-star lighting transformer supplied from the 480V service is used to provide a 3-phase/4-wire power supply with a neutral for lighting and receptacles.

If you insist on using 3-phase/3-wire, lighting can be installed across the line if the voltage rating of the fixture is appropriate to the mains voltage. Many marine installations do not use a neutral, but the equipment is only accessed by crew, not passengers. I would not recommend using an ungrounded system where non-electrical professionals have access.

I taught my children that they need to either know the answer, or know where to get the answer.

If the OP has to ask, he should not do it.

Honestly that is very bad advice, sometimes asking can get you a lot of help and will be beneficial in the futur.

Some advice from me, if you can't help its better not to comment.

Thanks to everyone who posted a reply.

The line to line voltage is 230V. So i guess we can use a bulb rated at 230V and get the lighting circuit working. Just so used to connecting phase and neutral. Thanks

We are not allowed to distribute the neutral through the system thats why we're not using a lighting trasnformer to obtain a neutral

Hey, srika, you do what the customer supposedly want. Never mind the national and local code. When the s*** hits the fan, and you are sued, please report back to us on your misapprehension. Get it?

Have a good life, in the meantime.

Your comment is just sad, hope you have a good life too and your negativity helps you in the future.

The client requirement of the neutral not being distributed and the Lighting circuits also as IT distribution has been discussed and they maintain they want it. Its nice right when people on the internet supposedly knows what other people need. There are National and Local codes for IT Distribution btw. If you go towards the North Africa Side you may notice they follow an IT network. I don't know about Europe.

But hey you seem to be a genius, maybe when i ave the lawsuit i could contact you for law advice, you seem to know what to do.

Cheers

Does anyone know a good technical book to read about IT distribution system in Plants and how to go about it.

Could spare a lot of people here the headache.

Wikipedia.

It saves hiring a locally-qualified electrician!