Lighting Calc

[Alwayslearningelec]

Hello. I have a 120/208v distribution center. I have these ttwo fixture type that are site lights. What calcution would I use to determine circuit size? Also VD would be an issue as they are 500 to 800' away from source. I'm think I can use 20A breaker(s) but would need ot upsize wire then tap it down at panel and when I branch off to fixtures. Does that make sense?

 

[infinity]

Looks like each light is 25 watts. What voltage are you using, 277?

 

[Alwayslearningelec]

Looks like each light is 25 watts. What voltage are you using, 277?

It's deisgn build so that info is not given but I would assume that would be more effecient so I willassume/qualify 277v.

 

[infinity]

How many lights on a circuit? You could put 72 on a single 20 amp circuit. 1800 Watt/25=72

 

[Alwayslearningelec]

How many lights on a circuit? You could put 72 on a single 20 amp circuit. 1800 Watt/25=72

Is that 80% loading?

1800 watts is the watts for a 20@ circuit @ 277v?

 

[infinity]

Is that 80% loading?

1800 watts is the watts for a 20@ circuit @ 277v?

Yes 80% for continuous load.

 

[Ragin Cajun]

Careful with voltage drop. Bollards can stretch way out there.
Also, too many LED fixtures can cause false trips. Don't ask how I know. I just don't know the cut off number.
And when using dimmers, you are severely restricted in the load with LED's
RC

 

[kingpb]

The OP voltage is 208Y/120V, not 277V.

 

[infinity]

The OP voltage is 208Y/120V, not 277V.

Yes and post #3 says 277.

 

[Alwayslearningelec]

Looks like each light is 25 watts. What voltage are you using, 277?

Just curious why does it say 48W in the cut sheet?

 

[Alwayslearningelec]

Yes 80% for continuous load.

And the 1800W # is the watts for a 20A circuit correct?

 

[infinity]

Just curious why does it say 48W in the cut sheet?

Not sure, what you've posted says 25.0 W. How many were you looking to put on a circuit?

 

[Strathead]

It's deisgn build so that info is not given but I would assume that would be more effecient so I willassume/qualify 277v.

You started off by saying you have a 120/208 distribution system.

 

[Alwayslearningelec]

Not sure, what you've posted says 25.0 W. How many were you looking to put on a circuit?

However many allowed ...but need to make sure wattage I'm calculating is correct . It says 25 and also 48. Either way it's 1800/fixture wattage.

 

[Alwayslearningelec]

You started off by saying you have a 120/208 distribution system.

Yes but it's not designed so I just figured. But it would be better to distribute the power to the poles at 277v( since it's very long distances) I'd think even if I need to put transformer by service.

 

[d0nut]

Use 208V if you are worried about voltage drop. No sense in buying a transformer in this application.

 

[Alwayslearningelec]

GM. Just so I'm clear the 1,800W values comes from where?

 

[infinity]

GM. Just so I'm clear the 1,800W values comes from where?

Continuous load no more than 80% of the branch circuit rating. You started out by saying in the OP 120/208 volts so I can see the confusion because you later stated 277 volts. In my original example I used 120 volts. {20 amps*120 volts*80%=1800 watts} The value will change based on the circuit voltage.

 

[Alwayslearningelec]

Continuous load no more than 80% of the branch circuit rating. You started out by saying in the OP 120/208 volts so I can see the confusion because you later stated 277 volts. In my original example I used 120 volts. {20 amps*120 volts*80%=1800 watts} The value will change based on the circuit voltage.

1800W is for 277/480. What's the wattage for 120/208v?

 

[Knightryder12]

Is that 80% loading?

1800 watts is the watts for a 20@ circuit @ 277v?

Nope - 80% loading for a 20A circuit at 277 is 4432 watts. At 25 watts each you could put 177 fixtures per circuit, at 48 watts you could put 92 fixtures per circuit.