Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!uunet!psivax!torkil
From: torkil@psivax.UUCP (Torkil Hammer)
Newsgroups: sci.electronics
Subject: Re: 220 vs. 110 motor efficiency
Keywords: power
Message-ID: <2596@psivax.UUCP>
Date: 4 Apr 89 17:16:49 GMT
References: <3272@ihlpm.ATT.COM>
Reply-To: torkil@psivax.UUCP (Torkil Hammer)
Distribution: usa
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 30

In article <3272@ihlpm.ATT.COM> wrv@ihlpm.ATT.COM (Vogel) writes:
[Dual Voltage motor]
#
#Well, I went home wondering how this could be true.  I examined the
#pump motor, its rated:
#
#	9  amps @ 220v
#	18 amps @ 110v
#
#So, in my mild knowledge of electronics and Ohm's law, Power = E x I
#1980 watts in both cases.
#
#So somebody please tell me, is the pool guy whacko, or am I missing
#something?

He is correct.  What you are missing is the loss in the wire from the
outlet to the pool, which can be quite large if the pool is away from
the house.
Connecting to 220V will cut the current in half, and Ohms law applies
to the wiring (P=R x I x I) [but not to the motor] so the wire loss
is cut to 25%.
You can expect about the same wattage, but at 220V the pump is more
efficient due to the samller wire loss, so you can pump for shorter time,
hence the saving on the bill.  Also, you heat the wires less, which
might mean longer wire life, depending on its quality, as well as less risk
of fire.  If you have 220V available, you should convert.

Have fun and don't forget the sunscreen.

torkil of California.