Demand Metering Vs. Removed Load

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Wireit

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I am in the process of doing a demand "calculation/Demand reading" for an existing panelboard. I have taken a 30 day demand reading thus have the existing load data at hand.

The project will be removing a few general purpose receptacles with no new replacement. Why can I not remove the 180va for each receptacle from the demand reading? Do I just show the 30 day demand as the future demand even though these receptacles are elliminated.
 
If I understood this;) , I'd ask these questions:

Were the general use receptacles that are planned to be removed in use during the 30-day period? If so, is the utilization equipment attached to them going to disappear entirely or simply be moved to other receptacles within the same space?

I'm baffled though... Since the panelboard is existing, what are you going to do with the data since you are removing receptacles without replacement??
 
tallguy said:
If I understood this;) , I'd ask these questions:

Were the general use receptacles that are planned to be removed in use during the 30-day period? If so, is the utilization equipment attached to them going to disappear entirely or simply be moved to other receptacles within the same space?

I'm baffled though... Since the panelboard is existing, what are you going to do with the data since you are removing receptacles without replacement??
Click to expand...



The utilization equipment was in use during the 30 day demand reading. I am only relocating existing equipment on alternate circuits within the same space. No new load is placed on the panelboard.

In response to your second paragragh, I am attempting to explain to the plan review authority the existing vs future load.
 
You are not removing ANY load. Only relocating them. Therefore, if I am understanding you correctly, your demand load will be unchanged. Will the loads be on different phases after the move? Depending on the load distribution, it may change the phase loads, but seems like it would be negligable from 30,000 ft.
 
If you are preparing for a future project, then your 30 day metering will serve as a basis for adding future loads. But your present project did not require any metering. If you are not adding load, then there is no need to determine the existing load.

However, if your AHJ insists on a calculation that proves the facility has capacity for your project, you can do the following:
1. Find the highest demand level within your 30 days of measurement (demand in units of KW, not energy usage in units of KWH).
2. Add 25 %.
3. Add the amount of new load that you project will install (i.e., add ?zero? new load).
4. Compare the result with the capacity of the distribution system.

You can hang onto the results of this calculation, and use it in the next project. Simply insert the new load added in the next project in Step 3.
 
You can't just remove 180VA for each receptacle because you don't know if any of those receptacles were in use during your demand reading. If they wern't in use, they didn't show up in your demand readings. So you could be subtracting them from a number that they wern't in to start with.


Wireit said:
The utilization equipment was in use during the 30 day demand reading. I am only relocating existing equipment on alternate circuits within the same space. No new load is placed on the panelboard.

In response to your second paragragh, I am attempting to explain to the plan review authority the existing vs future load.
Click to expand...

Was the demand readings taken before you relocated things to different phases? If so, I don't feel your demand data is much good. It is hard to say how rearranging loads will affect the demand. (Unless you are specifically trying to balance the loads better. Then I suppose one could assume the demand would only be less than your measurments on the worst phase.)

It seems like you might either have a very picky inspector, or maybe you are really trying to cut the loads close to the panels capacity. This just seems like too much effort for anything less than a really huge panel.

Steve
 
You may use actual demand to calculate load OR you may use a calculation to determine load. It appears that you are trying to mix the two methods. You are trying to use actual demand to justify something (I am not sure of your purpose or goal) and then reduce that number by a calculated 180 VA for some receptacles you are going to remove that may or may not have any load on them. Stick with one method or another. If the load is so close that a couple of receptacles will make a difference, it sounds like you have bigger problems.
 
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