How overkill are NEC calculations?

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I just realized something that may have biased my opinion. On my street, and my whole neighborhood for that matter, most of the homes are small and have gas or oil heat and gas hot water. And most use window air conditioners, if any cooling is used at all. So there is not a great deal of demand on the utility system for heating and cooling.

But move into the suburbs, with "McMansions" and central A/C, and I'll bet the utilities adjust accordingly.
 
peter d said:
But move into the suburbs, with "McMansions" and central A/C, and I'll bet the utilities adjust accordingly.
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Pete generally you will find pad mounts supplying the larger homes either dedicated or split between two dwellings.

The theory is the same, size the pad mount as small as possible, say for expected load and at peak demand times it may be run above it's rating.

This is far different than if we supply the transformer where it will be sized larger than the highest expected load.
 
peter d said:
But move into the suburbs, with "McMansions" and central A/C, and I'll bet the utilities adjust accordingly.
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Probably.

It's not unusual in my area to see one 15kva pot serving 10 or 12 older homes with gas or oil heat and major appliances. When I'm doing a service upgrade in this type of neighborhood, everyone from the engineer, scheduling dispatcher, and the lineman double and triple check with me that we're not adding load.
 
hillbilly said:
...To me, the transformer seems undersized and the voltage drop on the service conductors will (IMO) be excessive, but hey....what do I know? ...
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I'd say you have it exactly. As far as I know, the laws of physics for VD calculations don't change depending on which side of the disconnect you are on.

carl
 
I think Bob (iwire) is right on the logic between the lineman and wireman , and load logic applied. When getting insured at one time, my agent showed me the difference between inside electricians, and distribution workers, double the rate for them!

In regard to safety factor, I think we are somewhere between 200% and 300% over built for the situation at hand normally. Better too safe, than too sorry! Kind of like court, perception and reality, can be drastically different.
 
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