Power limit?

I have an electronic timer (the kind where you can plug appliances
into such as coffee pots, crock pots, etc.)
125 VAC 15A General Purpose
125 VAC 15A Resistive
125 VAC 1250W Tungsten
125 VAC TV-4 1/3 HP
My question is, can I safely plug a small window air-conditioner unit
to this? The unit is 515 Watts, 4.8 Amps, and 5,000 BTU.
I'm not sure which spec I'm supposed to be comparing to (if any). I
assuming the specs on the label of the timer refer to its maximum
limits (correct me if I'm wrong).
Thanks
Reply to
martin lynch
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A 1/3 HP single phase 115V motor may draw up to 7.2 Amps, according to the NEC. So I'd say a device containing one or more motors that draws less than this would fall within the timer's rating.
Sounds correct.
Reply to
Paul Hovnanian P.E.
In article , mart> I have an electronic timer (the kind where you can plug appliances
This is not my field of expertise, but 515 watts is significantly greater than 1/3 HP. The only motor rating given appears to be in the last line. I am pretty sure that TV-14 does not refer to a television channel. ;=) My guess is that the low rating has something to do with starting requirements.
Bill
Reply to
Salmon Egg
Or interrupting an inductive load. This usually takes a more robust contact design than simple resistive loads so they are rated for less when controlling motors.
daestrom
Reply to
daestrom
So in layman's terms, you're saying i can or cannot use this timer safely?
Reply to
martin lynch
That was what I was pointing out.
Bill
Reply to
Salmon Egg
In article , mart> > This is not my field of expertise, but 515 watts is significantly
If I could give you an authoritative answer to this question. then it would be within my field of expertise.
Bill
Reply to
Salmon Egg
I agree with Paul. The NEC gives a current of 7.2A for a 1/3HP motor. The air-conditioner is within the ratings of the timer.
Reply to
bud--
Thanks. The other thing to consider (not in this case, but for general information) is the 'Tungsten' rating. That is (based on the timer ratings) 10A. This is lower than the 15A general purpose rating since incandescent lamps (Tungsten) have a high inrush current when cold.
In the OPs case, his load falls within the 10A rating anyway, so all is well. Even though a window AC unit would be characterized as a motor load rather than a lighting load.
Reply to
Paul Hovnanian P.E.
But what does "TV-4" mean on the 1/3 HP rating?
another Bill
Reply to
Bill Shymanski
Thanks everyone, for your responses. I'll give it a go. If I end up burning my house down, I'll be sure to let you all know ;)
Reply to
martin lynch
Well, *you* mentioned 'starting requirements'. I was pointing out that is the *interrupting* of inductive current that would be the issue, not the initial closing.
This would be an issue even if it's just an inductive load such as a solenoid. There is no in-rush/starting current with a DC solenoid, yet the contacts would have to be over-rated for interrupting the current.
daestrom
Reply to
daestrom
| Salm|> |> |>> Or interrupting an inductive load. This usually takes a more robust |>> contact design than simple resistive loads so they are rated for |>> less when controlling motors. |> |> That was what I was pointing out. |> | | Well, *you* mentioned 'starting requirements'. I was pointing out that is | the *interrupting* of inductive current that would be the issue, not the | initial closing.
I learned the hard way what current through an inductor wants to do when it is interrupted. Back in the 1960's I had a Heathkit experimentation board. It was powered by 4 C cell batteries (safe, eh?). I was playing with my own circuit wirings and wired up the little relay with the coil and the normally closed contacts in series. It became a little mechanical oscillator. One thing I noticed was that it was a higher frequency than the other way which was to wire the normally open contacts to short out the coil when closed. It also had a nice blue arc as the contact opened (that should have been a warning). Being curious, I touched the relay contact arm. Got a good jolt out of that. That was no 6 volts.
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phil-news-nospam

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