mstrlucky74
Senior Member
- Location
- NJ
Can someone help me with the calculation to figure how many lights I can put on (1) 120v 20A circuit. Thank you.
Lights on 20A Circuit
- Thread starter mstrlucky74
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peter d
Senior Member
- Location
- New England
You can load the circuit right to 20 amps unless it's a continuous load.
- Location
- Massachusetts
kwired
Electron manager
- Location
- NE Nebraska
lighting is usually a continuous load - so 80% of 20 is 16 amps, divide by amps per fixture to come up with how many (of the same) fixtures you can put on that circuit.
mstrlucky74
Senior Member
- Location
- NJ
Lack a bit of information there
ie: using 5 watt lamps, non-continuous you can connect 480 of them, or (1) 1500w continuous lamp..
The F1D.
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- Location
- Massachusetts
Very much depends, more so today than every before.
For instance a large warehouse would have had a continuous lighting load, now most warehouses I go in have motion switching so no continuous loads.
Office buildings, again a lot of motion / occupancy / vacancy / ambient light sensors so while part of branch circuit could be continuous other parts of it not continuous.
I am not suggesting to ignore the rules for continuous loads I just think they are often over applied. No problem with that other than wasted copper.
- Location
- Massachusetts
It shows the F1D as 120 volts and 96 watts. If it was me I would want to see a cut sheet on the fixture or the ballast cutt sheet but we will assume 96 watts is accurate.
A 20 amp 120 volt circuit can provide 2,400 watts non-continuous or 1,920 watts continuous.
That being the case 20 or 25 F1D fixtures max on a 20 amp circuit.
As a rule I don't max out my lighting circuits from the start, it is nice to have some headroom in the circuits to add fixtures if the customer feels the need to.
peter d
Senior Member
- Location
- New England
- Location
- Massachusetts
With LED's and 277 volt circuits, that is hardly a concern anymore.
You are right there for sure.
The only thing limiting circuit size now is a how much of an area can you afford to have dark if one circuit goes out.
kwired
Electron manager
- Location
- NE Nebraska
I'll just say such controls is something to consider. Every application will have different demands, many may never run for three continuous hours, yet that one activity/event every so often may have them on for much more then three hours.Very much depends, more so today than every before.
For instance a large warehouse would have had a continuous lighting load, now most warehouses I go in have motion switching so no continuous loads.
Office buildings, again a lot of motion / occupancy / vacancy / ambient light sensors so while part of branch circuit could be continuous other parts of it not continuous.
I am not suggesting to ignore the rules for continuous loads I just think they are often over applied. No problem with that other than wasted copper.
- Location
- Massachusetts
Read the definition of continuos load, notice they use the word 'expected'.
mstrlucky74
Senior Member
- Location
- NJ
Very much depends, more so today than every before.
For instance a large warehouse would have had a continuous lighting load, now most warehouses I go in have motion switching so no continuous loads.
Office buildings, again a lot of motion / occupancy / vacancy / ambient light sensors so while part of branch circuit could be continuous other parts of it not continuous.
I am not suggesting to ignore the rules for continuous loads I just think they are often over applied. No problem with that other than wasted copper.
Great point
mstrlucky74
Senior Member
- Location
- NJ
Thanks
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