208V Single phase wiring from 3 phase 4 wire disconnect

[HoosierSteve]

I work in a location that was once a Machine shop showroom. We have 208/230/480 etc in the building. I need to install a temperature chamber that requires single phase only 208V or 230V supply. I have a 100 amp rated disconnect literally in the exact location this needs to go. I've read for hours and while I understand the basics of phased electricity supplies, I don't find anything definitive that gives me enough confidence to connect our new $24K instrument to this disconnect. The 3 phase system here uses red/blue/black color coding and does have a 4th wire neutral or ground. Can I safely run a single phase device from 2 phases of the disconnect? Are A and C the ones to use or does it matter? What do I do with the 3rd wire from the chamber? Is it tied to that neutral/ground also?

I know this topic gets beat to death, but looking for some reassurance on how to proceed? We're an electronic repair company and while we have lots of specialized knowledge in DC and RF, it doesn't translate all that well to phased electricity theory.

Thanks in advance!
Steve

 

[pc1966]

What does the chamber need? Spec, etc?

Some only need a 208-230V supply, others might expect/need a mid-point connection as your 110V-0-110V style of high power domestic supply has.
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Also to add if you do go to check voltages make very sure that your test meter is rated to at least 600V CAT-III if you are looking at a 3-phase board.

Measurement category - Wikipedia

en.wikipedia.org

Some of the better electronics style multimeters are (e.g Fluke 179) and you can get suitable meters for under £100 in the UK. It is important as a mistake with an underated meter can end very badly. And I mean very badly.
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Actually I should have been more specific, you must make sure that both the meter and the probes are suitably rated.

 

[Megawatt]

I work in a location that was once a Machine shop showroom. We have 208/230/480 etc in the building. I need to install a temperature chamber that requires single phase only 208V or 230V supply. I have a 100 amp rated disconnect literally in the exact location this needs to go. I've read for hours and while I understand the basics of phased electricity supplies, I don't find anything definitive that gives me enough confidence to connect our new $24K instrument to this disconnect. The 3 phase system here uses red/blue/black color coding and does have a 4th wire neutral or ground. Can I safely run a single phase device from 2 phases of the disconnect? Are A and C the ones to use or does it matter? What do I do with the 3rd wire from the chamber? Is it tied to that neutral/ground also?

I know this topic gets beat to death, but looking for some reassurance on how to proceed? We're an electronic repair company and while we have lots of specialized knowledge in DC and RF, it doesn't translate all that well to phased electricity theory.

Thanks in advance!
Steve

Steve welcome to the forum and yes you can put a double pole breaker in that panel. What amperage and voltage do you actually need
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Steve welcome to the forum and yes you can put a double pole breaker in that panel. What amperage and voltage do you actually need

We know the voltage but what is the amperage and is the disconnect fusible or non fusible

 

[HoosierSteve]

Hi all and thanks for the replies. The disconnect is 100 Amp fused with large fuses and tabs on the end, RK5 maybe. All the info I have right now is single phase optional 208V or 230V, 30A.

 

[Megawatt]

Hi all and thanks for the replies. The disconnect is 100 Amp fused with large fuses and tabs on the end, RK5 maybe. All the info I have right now is single phase optional 208V or 230V, 30A.

You will have to lower the fuses depending on what amperage you need and just use A and C phase and does that disconnect have a neutral or does the machine need a neutral

 

[HoosierSteve]

You will have to lower the fuses depending on what amperage you need and just use A and C phase and does that disconnect have a neutral or does the machine need a neutral

Thank you or the reply. I was planning to change fuses to 30A per specs and the disconnect does have a neutral so it will be there if needed. Phase A and C are effectively single phase though, correct? Not "truly single" as I understand it, but still usable as single phase.

 

[Megawatt]

Thank you or the reply. I was planning to change fuses to 30A per specs and the disconnect does have a neutral so it will be there if needed. Phase A and C are effectively single phase though, correct? Not "truly single" as I understand it, but still usable as single phase.

Steve yes it would be a 30 single phase application, just remove the B phase fuse

 

[HoosierSteve]

Steve yes it would be a 30 single phase application, just remove the B phase fuse

Thanks much! I feel good about this now.

 

[Megawatt]

Thanks much! I feel good about this now.

Good luck my friend with the $ 24,000.00 machine