277 Volt single phase water heater on 240 volts

Merry Christmas
Joethemechanic said:
So your residential areas there all have 400/230 y 3P transformers?

How about more rural areas, is there a system with only single phase medium voltage primaries coming off a larger 3p circuit?
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I posted this already:
"But we do have the standard for for the EU. It is 230V for domestic use and 400V for industrial. "

And yes, we do have single phase from primaries.
 
Besoeker3 said:
For what its worth, that single (230/400 EU) standard is larger than the whole of USA
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That may be true, but not surprising, given the adversity to regulation in the US.

Since Robin Hood booted the Sheriff of Nottingham from Sherwood forest, and the stash of ill gotten taxes were smuggled to America with the Sheriff’s entourage, US peasants have become suspicious of government, and vote for the Hood whenever possible.
 
ramsy said:
That may be true, but not surprising, given the adversity to regulation in the US.

Since Robin Hood booted the Sheriff of Nottingham from Sherwood forest, and the stash of ill gotten taxes were smuggled to America with the Sheriff’s entourage, US peasants have become suspicious of government, and vote for the Hood whenever possible.
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Yes, but the EU has around 400 million. Peanuts compared to Robin Hood.
 
Little Bill said:
If you calculate the power for 75% for the lower voltage you get:
12.2 x 75% = 9.15
9.15/240V = 38.12
38.12 x 125% = 47.65

You would need a 50A breaker & conductors
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Bill,
How did you get the 75%? Is that an approximation going from 277 to 240 volts?
 
I have questions. What was the previous WH specs? What is the current circuit? I mean, with an 80G heater, I would think it would already have a pretty big branch.

Another to mention, resistive elements have a tolerance! They will vary with temp. And the voltage is rarely a perfect 240V. All that would dictate a large enough circuit for a buffer, which is prob 50A.

If you want the full monte from that rig, just install a buck/boost and send it!
 
infinity said:
Bill,
How did you get the 75%? Is that an approximation going from 277 to 240 volts?
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The power dissipated by a resistor goes as the square of the voltage.

(240^2)/(277^2) = 75% (apporimately).

277 comes from 480/sqrt(3), and 240 = 480/2 So you get (480/sqrt(3))^2 / (480/2)^2 and the 3/4 just falls out of that.

-Jonathan
 
Yeah but for power circuit purposes it's current that matters, not BTU capacity. Current over a given resistance is 0.87 with that reduction in voltage
 
The current being at 87% would be "I" and once that is squared 0.87 x 0.87 = 75%.
"R" is unknown, but R stays the same
 
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