Sodium-Vapor Lamp

This may help you out -

Found it here: http://www.google.com/search?q=sodium+vapor+fixture+wiring+diagram&hl=en&newwindow=1&rls=com.microsoft:en-us:IE-SearchBox&prmd=ivns&tbm=isch&tbo=u&source=univ&sa=X&ei=RqTKTZLUMMbL0QGbxfiSCQ&ved=0CCgQsAQ&biw=1221&bih=694

It's hard to tell, but it looks like a bunch of ground wires that may, or may not be in use, and may go to other things besides the lamp. Just a guess. Are they insulated from the metal case?

the case was made of plastic, not metal.

Perhaps there is a temperature sensor there to keep the lamp from overheating, to make sure it runs at the proper temperature and thus to ensure long life. Likewise, there may be a timer circuit and/or daylight/nighttime sensor circuit to control on/off. Or perhaps wiring to a remote control sensor. Maybe all of the above.

Maybe simply some convenience connections for a daisy chain affair. Label those wires, pull them off and grab your trusty multimeter.

Only two wires comes in, the other might be grounding wires since they are conneted directly to the bolts.

I thought that could have been the case. but why is there more than one grounding wire required? the labels F and G seem to go to the top of the lamp post.

Those wires going to the top may go to a photocell to turn it off in the daytime. That is what they use for streetlights here.

I don't know this particular lamp - and the clarity of the picture at my end isn't the greatest. But I would hazard a guess that all those connection points are insulated from the casing and each other. My other guess are they relate to the lighting control cct of the sodium /vapour lamp. And the simplistic answer is the lamp only requires a simple cct to drive it. ie active (via the switch) and nuetral (not forgetting earth).

Well, whatever it is. It needs two wires to live (L,N) and one for our safety (G). All the others shall be interal wired.

This may help you

i have to need sv/mh 400 watts copper ballast

There seems to be 4 nut-bolts there and each connected to two wires. I can't understand the purpose of that.

Aaah Jay, not to put too much of an empasis on it but I don't think you have been reading any of the comments. I for one gave you the answer and the post by Hithuanand (#9) also is very clear. A number of the post are basically saying the same thing - you supply power via your active (A or L) and Nuetral (N), the rest is related to the light units control cct. (Also there is an earth in there some where as well)

It could be the bolts are terminals for the transformer. The bolts provide a secure tie point without the use of wire nuts or crimps. Looking at the diagrams its plausible this is the input side for installation and the additional wires are some of the start/igniter components.

I suspect your fixture has a multi-tap ballast. If you can read the label on the ballast, it will confirm or refute my guess. If it is a multi-tap, the stud & nut terminals are for connecting different voltages. The wires going to the top of the post are probably for a photo-cell to automatically turn the light on at dusk and off at dawn.

A photo of the ballast label (or at least a manufacturer & part number) and/or a diagram showing what component each wire connects to would be invaluable in providing further assistance.

Thanks. I don't know if I can get the photo of the ballast label.

You have a transformer a capacitor and sometimes a lamp starter, and then the bulb...

The actual wiring will vary from light to light according to design...

These lights are designed to last a long time, if the light is failing, it's probably time for a whole new light, as the design of the components changes over time and matching components becomes a hit or miss experiment that is too costly and time consuming to bother with...a new light becomes the cheaper option...