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#746 - 03/09/01 08:37 PM Formula needed  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
I'm looking for the formula that takes you from the power companies KWH reading to a given sized panel for a service upgrade.

any help appreciated...

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#747 - 03/09/01 08:54 PM Re: Formula needed  
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
There is no formula that I know of to convert KWH to amps.

If you have access to the peak demand you might be able to do something like dividing the peak demand by 240 volts (for single phase residential service) & getting an answer. If you have 3 phase, divide by the line to line voltage & multiply by .58. This would only apply to well balanced 3 phase services.

Tom


Few things are harder to put up with than the annoyance of a good example.

#748 - 03/10/01 04:12 PM Re: Formula needed  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
I'm stumped too! Seems that the only way to figure peak demands via the utility company would be using a Commercial type KWH meter [with the direct readings for peak demand on a separate set of dials], or if the month's consumption was high enough to reflect a large connected load.

If there is a way, let me know!!

Seems more to be what you have now [basic load calcs] and what you are adding to the existing system would be the only things needed to show that a service's ampacity would need to be increased.

I can see the utility companies wanting to have homeowners change out old antiquated services, especially the ones that have no main disconnect. Another change out would be 120 VAC 2 wire services on old-old houses. These would most likely be fuse only services [edison base].

After enough "Archie Bunkers" replacing blown screwshell fuses with coins behind them, I think the utility companies and even the building departments would go as far as paying to have those "fires to be" upgraded to something modern.


Just my thoughts.

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#749 - 03/10/01 06:11 PM Re: Formula needed  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Thanks fellas,
[Linked Image]
i posted the Q having a gut feeling that a formula would not have enough factors to exist.
some power companies have more detail than others, probably due to thier metering methods.
The Q came from a 6 unit building, 200A service, 6 meters w/ mains.

A service upgrade , to any given ampacity ,would then be done by getting some figures to work with from the power co. ( I got a peak billing month of approx 5500KWH )
and appling 220-35-1 which would be the maximum demand data avialable for a one year period) I have, in the past, recieved "peak" and "normal" figures , due to the metering methods as mentioned. I find this to be the most realistic approach.


220-35-exception,
not my first choice, thirty service calls , one for every day of the month? Let's tack on after hour charges, as that's peak usage.

220-32, optional calculation for multifamily dwelling,,,
unapplicable conditions
( electric heat went out with disco around here)

Back to part B of art 220,
gaining entry
run a tape measure
don't let the cat out
my dog don't bite....
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