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Old 07-02-2009, 10:53 PM   #46
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400 Amp Upgrade / Transfer Switch


Do I need continuous 400 amp service? No.

Do I need more than 200, potentially yes.

I looked back at my usage for this past winter. I will pull ~125 amps continuous when the HP is running and the resistance heat is engaged. (HP is around 30 amps and heat tape is 86). The steady state of my house is around 5 amps all the time.


Attached is a graph of today's demand. It was 70 out, so the A/C only came on once.

The WH seems to draw around 45 amps when it is running.
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Old 07-02-2009, 11:14 PM   #47
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400 Amp Upgrade / Transfer Switch


Quote:
Originally Posted by AndrewF View Post
Do I need continuous 400 amp service? No.

Do I need more than 200, potentially yes.

I looked back at my usage for this past winter. I will pull ~125 amps continuous when the HP is running and the resistance heat is engaged. (HP is around 30 amps and heat tape is 86). The steady state of my house is around 5 amps all the time.


Attached is a graph of today's demand. It was 70 out, so the A/C only came on once.

The WH seems to draw around 45 amps when it is running.
Those graphs are neat, what type of setup do you have that generates these?
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Old 07-02-2009, 11:22 PM   #48
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400 Amp Upgrade / Transfer Switch


I've enjoyed this thread. Service entrance intimidates me, so I am duly impressed. LOVE the graph.

As to the capacity: When has anyone ever wanted LESS power than they had?

When we bought our house the POCO discovered that a lazy POCO employ shortcutted the line across my neighbor's property - rather than in the utility easement. At least they admitted it was their bad. They had to put in a transformer and re-run service to the house - upgraded to the transformer for free! Can't wait till I have the cash or the cojones to take the house from 200A to 400A. MORE POWER!
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Old 07-02-2009, 11:22 PM   #49
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400 Amp Upgrade / Transfer Switch


See this thread for some history on it.

HVAC Monitoring

I use Cacti for the graphs, and custom code for the rest.

http://enviro.onlinedesk.net
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Old 07-03-2009, 10:13 PM   #50
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400 Amp Upgrade / Transfer Switch


Wow: 45 Amps for a water heater? Do you have simultaneous operation of the heating elements?

Most water heaters rated at 4500 watts draw about 18.75 Amps. Dual 5500 watt elements would draw 45 Amps or so ....

That 25kVA transformer can handle loads such as you have posted just fine. The times when you are over the 100 Amp threshold are short, not enough to flinch such a transformer.
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Old 07-04-2009, 08:33 PM   #51
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400 Amp Upgrade / Transfer Switch


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Wow: 45 Amps for a water heater? Do you have simultaneous operation of the heating elements?

Most water heaters rated at 4500 watts draw about 18.75 Amps. Dual 5500 watt elements would draw 45 Amps or so ....

That 25kVA transformer can handle loads such as you have posted just fine. The times when you are over the 100 Amp threshold are short, not enough to flinch such a transformer.
I am speculating the WH draws 45 amps based on when it is on and the current draw at the time.

I'll try to put the clamp on meter on it sometime and confirm that. The WH was here when I moved in, only about 1 year old.

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