new to 3 phase 208v

[floodo1]

so, my new spot has 208v 3 phase. I believe it's referred to as 120v/208y?

In any case I'm used to the typical residential 120/240 single phase setup, and I've got a bunch of magnetic ballasts setup for 240v right now. I've read a couple of things online which I'd like to get some more information about:

1) Can I simply run these (magnetic) 240v ballasts on 208v? If so is there any downside to this? Seems like i'd only be getting partial light if it even worked at all.

2) Can these ballasts be converted to run on 208v? I've read on many sites that sell ballasts that they can be taken apart at use a center tap on the transformer (or so they say) to run at 208v....can anyone advise me on this?

Also, since the ballasts say 9.5amps at 120v and 4.75amps at 240v, will they be using basically 5.5 amps at 208v (if you can convert them)??

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Finally, If these can be run on 208v what should I do for timers? Will I need to run 120v timers via contactors to control the 208v?

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PS- I understand the electrical aspect no problem. 3 phase and the voltage and everything isn't the problem....it's how typical grow equipment works with a 3phase 208v setup that is the issue. If I was trying to hook up some phatty industrial motor I'd have no problem...just grow lights (cuz all the rest of the equipment is 120v which is easy enough to deal with)

thanks in advance

 

[convex]

It has been decades since I worked in three phase, but I am sure the few recollections I have will still be germaine to todays distribution ...

Running a 240v appliance on 208 will indeed work, but at a reduced performance.
However, single phase 110v IS accounted for in these systems and works rather seamlessly

Ideally, a single phase distribution panel off the 3 phase system is installed to allow efficient use of 240v appliances.

Cheers

 

[Underground]

If there is not a multi-tap ballast in there already, you can put one in. Yes they are like an auto-transformer on the primary side of the ballast, but you don't have to take apart to retap it.

Ideally, a 2 phase distribution panel off the 3 phase system is installed to allow efficient use of 240v appliances.

Cheers

Except in the case of old industrial applications, most electricians won't even see 2 phase. I haven't. But what you are referring to is actually a single phase panel (Two hots and a neutral). But either way, this does not allow for more efficient use of power.

 

[convex]

As I say, been decades ...

Forgot about a transformer when brining it down to single phase before the new distro panel, giving true single phase, rather than continuing on just 2 of the three legs and proper balancing ...

Underground:
At this point it SHOULD be more efficient use, should it not?
My memory ain't the greatest, but wouldn't mind having a refresher.

Cheers

 

[hiboy]

Yes its called 120/208 volt. I've seen many appliances run on 208 volt. Normally the specs will tell you that. As for the ballasts i would contact the manufacturer. ANd for the timer issue get an intermatic T103 or T104, forgor which one. Its the kind with the big yellow dial like a clock. Just make sure the motor on the back of it says 208v, 277v. You wont get 240v single phase if you run a panel from it. You could check into a small transformer. Maybe a buck n boost type

P.s. Theres no such thing as 2 phase

 

[convex]

Yes its called 120/208 volt. I've seen many appliances run on 208 volt. Normally the specs will tell you that. As for the ballasts i would contact the manufacturer. ANd for the timer issue get an intermatic T103 or T104, forgor which one. Its the kind with the big yellow dial like a clock. Just make sure the motor on the back of it says 208v, 277v. You wont get 240v single phase if you run a panel from it. You could check into a small transformer. Maybe a buck n boost type

P.s. Theres no such thing as 2 phase

Your are correct sir,!
Fat finger syndrome -'fuggin' typo.-

Thats what happens when I don't proof read before hitting post!

- see if I can edit it

 

[Underground]

There is such thing, it's just no longer commonly used.

 

[deacon1503]

So what's the best way to run 240v sub panels off a 3 phase main service panel?

 

[hiboy]

So what's the best way to run 240v sub panels off a 3 phase main service panel?

They do make a transformer, primary: 120/208v secondary: 120/240v
You could just run your lights 120v and not dick with it. I think it might be a big cost to change your voltage. Probably easier doing that

 

[max_well]

Hey floodo1
If you're used to running a timer controller that runs controls several ballasts at 240v using a relay controlled by a 120v timer, you should be able to do the same in 3 phase.. your controller will wire to a double pole breaker connected across 2 legs, and the outlets will thus provide 208v. I believe that this should be fine for your ballasts assuming you can rewire them to 208v.
Anyone have insight about running different brands of digital ballasts on 208v? I've seen Lumatek states that their e ballasts are "generator ready" and can handle 208v three phase. Anyone know about Galaxy or Quantum?
good luck
Max

 

[Underground]

So what's the best way to run 240v sub panels off a 3 phase main service panel?

That really depends on your criteria for best. This is how many large apartment buildings operate. The first unit would be A-B phases, second would be B-C phases, third unit would be C-A phases.

The best way depends on the situation. Ideally you would do some load calculations and take real world measurements at your panel and try to balance the load. And if the available power source is 120/240v single phase, equipment should be spec'd that way. Or at 120/208v 3 phase if that's what's available. If you've moved into a space that differs from your existing equipment you can use buck boost transformers, or as hiboy suggested use a transformer that provides the correct voltage.

Much of today's digital equipment is designed sense and run at varying voltages, so there may not even be a problem.

 

[floodo1]

thanks for the information guys. I already knew that there is no way to get 240v from a 120/208 setup without using a transformer.......but since 208 timers are available and apparently magnetic ballasts can be changed to 208v, I'm going to put an equal number of lights on each phase (wired phase to phase) to balance the load and run them directly on 208v. Then I can add in a couple 120v circuits (wired phase to ground), to run everything else.

the crucial help so far has been that Intermatic makes most of their timers available in 208-277v or 208-240v. I'm used to using these with 6 lights on them at 240v, so I can just continue with that but at 208v !!

So now the only remaining question is to ask how do I go about reconfiguring my ballasts for 208v? If the ballast transformer isn't clearly marked 208v on one of the taps, what do I do? also if it IS marked 208v on one of the taps do I just disconnect the 240 tap and put the 208 tap in it's place?

Reason I ask so generically is that I have quite a few different brands of ballast already, and I haven't got a chance to take them all apart.

---

Finally, thanks for the info on digital ballasts, but a) I already know that the majority of them can run on 90-240+ b) I'm not going to be buying any since I already have magnetic ballasts

 

[hiboy]

Ive wired many lighting ballasts, just not the kind were talking about. You were asking about the wires if there is a 208v tap, yes one hot goes on there which will come from the existing hook up on 240v, and the other SHOULD just stay where it's at. BUt i would double check with the manufacturer.

 

[grinkeeper]

so what about any performance changes using 208.. I have a step down transformer that takes my volatage from 600volts down to 208v and 120volts.. this transfomer is about 120 pounds and roughly the size of a 3/4 hp chiller..

its a 15kva transfomer..

but I have lights that are digital ballasts that can operate on 120-240 and rated to operate off deisel or gas genetors with flucuating voltages...

So I want to reduce amps and run max volatge, I know this wont really save on power usage, thats a big myth.. but it will allow me to use smaller wire gauge with out getting hot.. plus reduce the amperage of the whole system.. I want to run 8 ballast eventually once the permits are in place but for now I am just sticking to the current limitations...as far as plant numbers..

So with my digi ballast.. I should get the electician to wire up the boards at the max voltage that the transfmomer can put out then which is listed on the transfomer tag as 208VOLTS..

does this sound correct.. and it will allow me to operate more lights than if I ran 120volts..????????
and I wont see a reduction in light output??????

 

[1971]

thanks for the information guys. I already knew that there is no way to get 240v from a 120/208 setup without using a transformer.......but since 208 timers are available and apparently magnetic ballasts can be changed to 208v, I'm going to put an equal number of lights on each phase (wired phase to phase) to balance the load and run them directly on 208v. Then I can add in a couple 120v circuits (wired phase to ground), to run everything else.

the crucial help so far has been that Intermatic makes most of their timers available in 208-277v or 208-240v. I'm used to using these with 6 lights on them at 240v, so I can just continue with that but at 208v !!

So now the only remaining question is to ask how do I go about reconfiguring my ballasts for 208v? If the ballast transformer isn't clearly marked 208v on one of the taps, what do I do? also if it IS marked 208v on one of the taps do I just disconnect the 240 tap and put the 208 tap in it's place?

Reason I ask so generically is that I have quite a few different brands of ballast already, and I haven't got a chance to take them all apart.

---

Finally, thanks for the info on digital ballasts, but a) I already know that the majority of them can run on 90-240+ b) I'm not going to be buying any since I already have magnetic ballasts

If your ballast doesn't have a 208v tap, you can't run it properly at 240v or 277v. That is why they make a tap for that specific voltage. rather than trying to do a big work around, why not buy a quad tap ballast so that you get the 208v tap.

 

[1971]

So what's the best way to run 240v sub panels off a 3 phase main service panel?

You would get a 2 pole breaker and route the power to the sub-panel... making sure you size everything properly. the ground and neutral bar on the sub panel would not be connected and of course you'd run a ground and neutral.

In terms of 3 phase, it is only more efficient with motors. With lighting the higher voltages simply allow you to run more lights on a circuit.