I'm having trouble finding a chart or a way to convert Tons (air conditioners) to amperage.
I know this much:
1 ton = 12000 BTU
1 BTU/minute = 17.5 watts

What I have is a two ton air conditioner unit rated at 240 volts (single phase). Based on this information, how do I come up with an amperage? Any help would be appreciated.

You don't other than perhaps the roughest estimate.

You have to look at the nameplate ratings in order to determine the actual load.

That's the problem IWire, they want the wiring installed before the unit is put in place, so there is no nameplate info available. I run into this quite often, and end up calling the HVAC guy for more information. Was hoping there was a simpler way to do it.

The way we would handle this would be simple.

If they want the wiring done they will have to provide specifications or they can agree to pay to much for an oversize circuit.

Just my opinion, Bob

"If they want the wiring done they will have to provide specifications or they can agree to pay to much for an oversize circuit."

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You bet Bob, they are always in a panic, to get it wired first.

One thing to remember, we always do a load calc, to insure the existing service will take the additional load, this is also required by our utiliy.

Failure to do a load calc., may have you paying out of pocket, for a service upgrade.

For a 2-ton split-system A/C condensor, a 20 amp line should be sufficient. I say maybe because the 20 amps might only meet the minimum over current protection that is required. Whenever I run lines for an A/C circuit I prefer to meet the maximum OCP.

But to be on the safe side, I'd either find out for sure the requirements, or just run some 10-2 NM and be done with it.

Good luck.

For a 2 ton system, it could be anything, best to always check the name plate, we had 2 tons with 25A, 30A,and 40A, a lot depends on the type of compressor.

Might be different depending on if it is a conventional compressor or a scroll compressor.

[german accent]DEmand, SpeCifiCaTionS!!!, JusT TeElLL Dem, "GEEvE Me a MOOdldel NuMBa, VolTAge and AmpeAge, wit FLA, Or Get BEnT!"[/german accent]

Really, tell them to throw you a bone, you're not calcing the air, just the power to it.....

Or price each at 100A 3 phase, or T&MX1.859, after unit is in place. (Hassle factor of 5)

7 amps per ton and sized per min nameplate

7 amps per ton?

That can't work without knowing the voltage and phase.

Bob

We'll settle for Kva/ton.

For what it's worth:

Tons of airconditioning/ refrigeration was first used as a sales metric.

It is short for tons of ice delivered per day.

The latent heat of melting of one ton of ice is 288,000 British Thermal Units... BTUs.

Across 24 hours that is 12,000 BTU's PER HOUR.

Hence the term 12,000 BTU's = one TON of airconditioning.

The sales metric started when machines replaced delivered ice. The pitch ran: this machine delivers the same cold as having one ton of ice delivered each day to your establishment.

High efficiency units are now mandated by US Federal Statue. (Law)

Higher effeciency units use ever less juice to crank out a 'ton of air conditioning'.

It is not uncommon to find units with a co-efficiency of performance (COOP) above 10.
That is ten watts of juice produce 100 watts of heat transfer.

Until you know what the nameplate figures are, you'd better figure on the customer buying an energy pig. They ALWAYS sell at a discount --- cheap, cheap.

Low performance refrigeration is financial folly. The extra money spent on the best unit typically returns over 50% on the expense.

Installing the most economic HVAC would keep them and us busy for years even as it saves the users a fortune.

It's that the payback for high performance is hidden from the ultimate buyer. Globally, the world has a long, long way to go. If the ultimate payer was informed... he'd never accept the low efficiency units that are normally installed.

Every manufacturer has a minimum circuit ampacity and most have a max size as well. The installer should have this info for you, it is dependent on SEER rating. Here is the goodman site, check specifications, a good amount of info will pop up in a .pdf, with min and max circuit sizes:
http://www.goodmanmfg.com/consumer/changeTab.act?newTab=Product&requestedSite=Goodman