I have a hot tub that I'm getting set up and it can be wired with 110 or 220
volts. I want to weigh the options and need to understand the benefits of
each option. At this point I know that wire and breaker for 110 will be
quite a bit cheaper. The amperage rating at 110 is only 20amps and a single
pole GFCI breaker and the thinner guage wire will be significantly cheaper
than the double pole 50amp breaker and the heavier wire that I would need
for the 220 option. This is about all I understand about the differences. I
have this vague notion that the 220 will be cheaper for me in the long run
but I'm not certain why. Could someone help broaden my understanding of the
Thanks ahead of time,
Those numbers don't make sense for an "either" situation.
if it was a choice, the watts would total to be the same in
either case. 20A@110V would be 10A@220V, not 50A. Without
being able to see it (or the manual/installation guide) I'm
going to hazard an educated guess that you need *both*.
The 110V is likely feeding pumps and lights, the 220V will
be for heating elements.
But hey, I could be wrong. ($1 Dennis Miller)
The real Tom Pendergast [ So if you meet me, have some courtesy,
aka I-zheet M'drurz [ have some sympathy, and some taste.
Ah, maybe you have those amp requirements backwards?
120v requires twice the amperage as 240v. (or provides 1/4 the heat,
depending on the wiring)
Of course, if you really need 110 or 220 you will have to invest in a
transformer, and that will really jack up the prices.
Hook it up to 220V (actually, it's more like 240V), because at 120V it's
going to take forever to get hot. You can save a little by using
aluminum SE cable. There's a lot of details to wiring it up safely and
according to the wiring codes. And you need still need a GFCI.
No offense, but if you're asking basic questions, you really shouldn't
tackle a job like this yourself. Hire an electricial, or do a lot of
I don't know if he needs a neutral or not. (probably does) If so, he
can use SE cable type "R", a.k.a. SER. My point was that aluminum wire
is appropriate for high-amperage circuits like this.
Buried somewhere in your users guide it is going to tell you that it takes 4
times as long to heat up the tub at 120v and that you can't run the pump and
the heater at the same time.
If you go the 240v route you can run the tub at it's full capacity. You will
need a 240v 50a GFCI breaker but that will really be the most expensive part.
email@example.com (Greg) wrote in message
Bingo! That's absolutley correct. The heating element remains the
same, so with 120V the power to the heating element is 1/4 what it
would be with 240V. And however hot it gets before you turn the pump
on, it's all down hill from there, cause with 20 amps, there isn't
enough current to run the pump and the heater. Plus, if you want to
keep it at a lower temp most of the time to save energy and only raise
it to full temp prior to getting in, it will take so long at 120V as
to be impractical.
Now why it's so hard to find these simple facts out, I don't know. I
went through this 15 years ago when I bought a spa for inside my home.
The best explanation of the difference I could get from the dealer
what, 120V is fine for inside, 240V is only needed for outside, it
heats a little slower. When I figured out the truth, before I even
turned it on, I had to pay them to come out and switch the power pack
in the unit so that I could go to 240V. Now this has me wondering,
was it really necessary to switch it? Seems like it was, since I
watched them and they did in fact switch it, so I may have had one
where the packs were in fact different.
I would only go with 120V if running 240V was nearly impossible.
Also, make sure you check code requirements for GFCI, accessable
disconnect near the spa, and bonding of any metal near spa.
Most I have wired is a simple conifguration plug that has to me removed and
changed on teh power unit or straping options inside the unit, etc. usually
does not require units to be replaced to operate on either 120 or 240V
I don't think he means the line cord "plug". Pool pump motors usually have an
internal plug to swap from 120 to 240 and I assume he means another
"configuration" plug that you move to select 120/240 in the controller.
I agree with I. You have something wrong. Those numbers are not right.
110 @ 20 amps is 2,200 Watts. 220 @ 50 amps is 11,000 amps. It can't
I also agree that if you did not see this yourself, you need to hire a
professional for this job.
The 120v "option" is indeed a sales tactic. This way, the salesmen can say "Oh
it plugs into any ordinary 20a circuit" and not be lying. When this option is
employed, the tub will not run both pumps (if it has 2 pumps) simultaniously.
It's one or the other. It also will not heat while a pump is on anthing other
than it's lowest "maintainence/filter" setting. And like you said, it will take
a lot longer and use signifigantly more power to heat.
He has it right. The majority of the amps are for the heater, which
is the same unit whether 110 or 220. So the current drawn is twice as
much at 220 and the heater generates 4 times as much power/heat. And
the control unit won't allow the pump to run at the same time as the
heater with 110, while with 220, it will, so this adds to the current
needed at 220 too.
Hold on there a minute. I am not sure what you are saying, but it seems
you are saying that it takes more total power, to heat a given amount of
water the same temperature rise using 240V than using 120V. If so that is
just not right. No way.
BTW where are you getting this 4 times thing? I have been letting it
ride because of issues with heaters designed for 120 vs. 240, but that just
is not so.
10 amps at 240 = 20 amps at 120. With resistance heat there is just no
way you are going to make any serious change in that! I see no way you are
getting this 4X thing. Maybe you should re-think that again or maybe we
are just not communicating well at all.
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