chimp1
Member
- Location
- Palm Bay, FL US
When calculating the total power of a 120V panel with just lights and receptacles in the panel would you multiply by sqrt 3 even though the loads are purely resistive?
Calculating total power of a panel
- Thread starter chimp1
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jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
No. Whether the loads are resistive or not is not a factor. Number of phases will be a factor.
Do you really have a 120V panel or a 208/120 panel with only single phase 120V loads.
Do you really have a 120V panel or a 208/120 panel with only single phase 120V loads.
Last edited:
kwired
Electron manager
- Location
- NE Nebraska
square root of 3 only applies to three phases with equally balanced current across all three phases, any unbalanced portion of current does not apply this factor.
But this factor is for figuring out how current divides for a specific power level. Power is still power. 1000 watts is still 1000 watts no matter what the voltage or number of phases is.
Maybe OP wants to clarify just exactly what he is asking?
But this factor is for figuring out how current divides for a specific power level. Power is still power. 1000 watts is still 1000 watts no matter what the voltage or number of phases is.
Maybe OP wants to clarify just exactly what he is asking?
chimp1
Member
- Location
- Palm Bay, FL US
3 phase panel with resistive loads
3 phase panel with resistive loads
If a 3 phase panel with 3 120V lines and a neutral suppling the panel and there are only lights and receptacles in the panel wouldn't you calculate the total VA by sqrt 3*V*A
3 phase panel with resistive loads
If a 3 phase panel with 3 120V lines and a neutral suppling the panel and there are only lights and receptacles in the panel wouldn't you calculate the total VA by sqrt 3*V*A
Yes, if "A" is three phase amperes, i.e. the same or maximum magnitude of amperes on all three ungrounded feeder conductors.
kwired
Electron manager
- Location
- NE Nebraska
Not exactly. Chances are you know total VA. What you don't know is total A per phase until you divide the (balanced portion) by the square root of 3.
If you know (balanced) amps per phase then you multiply that by by square root of 3 to get the actual (balanced) VA.
Any unbalanced amounts need added individually to the balanced amount on the phases they are connected to.
BAHTAH
Senior Member
- Location
- United States
Panel Load
Panel Load
Since the loads in your question are Lights and Receptacles you will never see a balanced load. When your calculating panel loads you determine the total VA. This would
include the application of non-continuous and 125% of continuous loads. For a 208/120 3ph4w panel just divide the total VA by 360 (208 * 1.73).
Panel Load
Since the loads in your question are Lights and Receptacles you will never see a balanced load. When your calculating panel loads you determine the total VA. This would
include the application of non-continuous and 125% of continuous loads. For a 208/120 3ph4w panel just divide the total VA by 360 (208 * 1.73).
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