How to calculate total household load

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Old 12-15-11, 02:24 AM
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How to calculate total household load

I had a new heat pump installed last summer and when it kicks in without aux heat it dims the lights momentarily surely thats not normal. How do I calculate the watts drawn by the heat pump? Thanks so much

David Keith
 
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Old 12-15-11, 05:09 AM
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It should be written on a sticker on the heat pump, look for specs listing voltage and amps.

Amps X voltage = Watt

Hopefully that sticker will list the MAXIMUM amperage drawn by the unit, which should give you a good idea of what it uses when starting.


It's possibly normal that your lights dim if that pump draws a ton of power. Is the main electrical panel rated for appropriate amps for the new heat pump?
 
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Old 12-15-11, 05:29 AM
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It is not unusual to notice some dimming when large loads start up. This may be an issue with the power company equipment sizing or it could just be normal.
 
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Old 12-15-11, 06:40 PM
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No the sticker just says 4.3 amps 200-230 volts and yes the main panel is 200 amps but now the power company says back 25 years ago they used lighter cable and it could be too light and they will replace it for 8 something a foot plus I provide the conduit and ditch.......at a 145 feet
 
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Old 12-15-11, 07:30 PM
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4.3 amps is very very little, meaning it's probably be the full load ampacity (Normal running amps).
If that's the case, then the STARTING amps required could be as much as 25 amps!! (check the rated amps on the breaker feeding it, i bet it's 30A)


You're also saying that your power company will provide 8 AWG. Depending on the heat rating of those cables, it could be 85 amps to 100 amps per hot leg, totalling 170A to 200A, which sort of makes sense for a 200A box.

Now that means you probably currently have 10AWG feed, meaning 130A to 170A total.

So, sort of makes sense, since all your lights dim regardless of which circuit they are on.

Lots of work to get the utility company to provide the proper gauge cables.

Overhead for the win!!!..... but generator required (Lots of trees )

So ya... if they say they're UPGRADING the feed to 8 AWG cables, it means you were at a smaller gauge. 10AWG is the next size in decreasing size, which gives a total of 8
 
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Old 12-15-11, 08:31 PM
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Not 8 gage wire. $8 per foot. O/P wrote:
they will replace it for 8 something a foot
 
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Old 12-15-11, 08:45 PM
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Originally Posted by ray2047 View Post
Not 8 gage wire. $8 per foot. O/P wrote:
Jennifer Henry Christian!

PLUS the underground raceway & PVC?

That will costs a few thousands unless he digs the trench and lays the PVC. Makes us wonder why they claim the price of kW includes "delivery" cost
 
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Old 12-16-11, 06:11 AM
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Different power companies have different rules, but the cost of upgrading the infrastructure for some power companies is on their dollar for one utility I deal with.
 
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Old 12-16-11, 09:42 AM
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A good reason to prefer drops to laterals if available. Drops are usually free.
 
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Old 12-16-11, 07:03 PM
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You're also saying that your power company will provide 8 AWG. Depending on the heat rating of those cables, it could be 85 amps to 100 amps per hot leg, totalling 170A to 200A, which sort of makes sense for a 200A box.

Now that means you probably currently have 10AWG feed, meaning 130A to 170A total.
I want some of what you are drinking!!
 
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