Residential Standard Calc and Additional Lighting Loads

[infinity]

When using the standard calculation how do additional lighting loads such as ceiling down lights get factored into the general lighting load? Say a house has 40 down lights with maximum 75 watt lamps. Do we only need to consider the sq foot area in the calculation?

 

[petersonra]

When using the standard calculation how do additional lighting loads such as ceiling down lights get factored into the general lighting load? Say a house has 40 down lights with maximum 75 watt lamps. Do we only need to consider the sq foot area in the calculation?

Is there any place in the calculation where the calculation says it has to be considered separately?

In some respects, this kind of thing is like tying to determine what might happen if someone decides to try and heat their house with space heaters and adds a 1500W heater in every room that could potentially be on simultaneously. It is just not something covered.

 

[infinity]

Is there any place in the calculation where the calculation says it has to be considered separately?

In some respects, this kind of thing is like tying to determine what might happen if someone decides to try and heat their house with space heaters and adds a 1500W heater in every room that could potentially be on simultaneously. It is just not something covered.

I was looking at a load calculation for an existing dwelling where there are 40 or 50 fixtures each with 75 watt lamps. If using the standard calculation I'm tying to see if there is a requirement to include this load since it well exceeds the 3 VA/sq ft portion of the calc.

 

[Smart $]

I was looking at a load calculation for an existing dwelling where there are 40 or 50 fixtures each with 75 watt lamps. If using the standard calculation I'm tying to see if there is a requirement to include this load since it well exceeds the 3 VA/sq ft portion of the calc.

220.12 says the calculation using 3VA per sq. ft. is the minimum. If the general lighting load exceeds that, then that's the amount you have to use in the standard calculation.

 

[curt swartz]

I was looking at a load calculation for an existing dwelling where there are 40 or 50 fixtures each with 75 watt lamps. If using the standard calculation I'm tying to see if there is a requirement to include this load since it well exceeds the 3 VA/sq ft portion of the calc.

That is a lot of lights per square foot. (40) 75 watt lamps in a 1000sqft house would be 3W/sqft.

I agree with Smart. The 3VA is the minimum required. If the lighting load exceeds that you should allow for the additional load. If this for the servcie load calc I really don't think there would ever be an issue since the NEC load calcs are overkill anyway. If this calc was for a feeder just feeding the lighting then the excess load could be an issue.