Calculating spare capacity on street lighting cicuit

[benjho]

Hi,

Can anyone help me calculate the spare capacity in a street lighting circuit?

Im looking to add additional lighting to an existing circuit but unsure how and what calculations and info I need.

Also, what power does the average street lamp draw?

Thanks,
Ben

 

[waross]

Panel rating X 80% minus the connected load gives the spare capacity, (Adjusted for center tapped single phase, OR line to neutral or line to line three phase.).
Average, would that be a weighted average? Street lights have ranged from 6.6 Amps to 20 Amps and from about 125 Watts to 1000 watts with exceptions. You can't use average to calculate the number of spares. The average may only be important for specific homework questions.
A Google search finds this information on WW Grainger.
"HID Ballast Kit, Core and Coil Ballast Type, High Pressure Sodium Lamp Type, 400 Lamp Watts, 120/..... Input Voltage, Number of Lamps 1, ..... 464 Input Watts,"

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jghrist]

Power factor depends on the type of lamp and ballast. The circuit might be limited by voltage drop as well as thermal capacity. You will need cable impedance to check voltage drop.