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#66263 - 05/28/06 09:45 AM Tonnage conversion
Sixer Offline
Member
Registered: 08/08/05
Posts: 264
Loc: Canada
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.
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Sixer

"Will it be cheaper if I drill the holes for you?"
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#66264 - 05/28/06 10:01 AM Re: Tonnage conversion
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
You don't other than perhaps the roughest estimate.

You have to look at the nameplate ratings in order to determine the actual load.
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#66265 - 05/28/06 12:01 PM Re: Tonnage conversion
Sixer Offline
Member
Registered: 08/08/05
Posts: 264
Loc: Canada
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.
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Sixer

"Will it be cheaper if I drill the holes for you?"
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#66266 - 05/28/06 12:07 PM Re: Tonnage conversion
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
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
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#66267 - 05/28/06 12:53 PM Re: Tonnage conversion
LK Offline
Member
Registered: 01/21/03
Posts: 1721
Loc: New Jersey
"If they want the wiring done they will have to provide specifications or they can agree to pay to much for an oversize circuit."

____________________________________________

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.
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#66268 - 05/28/06 01:14 PM Re: Tonnage conversion
ShockMe77 Offline
Member
Registered: 06/11/05
Posts: 823
Loc: Rahway, New Jersey
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.
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#66269 - 05/28/06 05:05 PM Re: Tonnage conversion
LK Offline
Member
Registered: 01/21/03
Posts: 1721
Loc: New Jersey
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.
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#66270 - 05/28/06 05:09 PM Re: Tonnage conversion
WFO Offline
Member
Registered: 09/03/05
Posts: 206
Loc: Cat Spring, TX
Might be different depending on if it is a conventional compressor or a scroll compressor.
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#66271 - 05/28/06 08:02 PM Re: Tonnage conversion
e57 Offline
Member
Registered: 05/27/03
Posts: 2837
Loc: S.F.,CA USA
[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)
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Mark Heller
"Well - I oughta....." -Jackie Gleason
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#66272 - 06/04/06 01:54 PM Re: Tonnage conversion
OreElect Offline
Member
Registered: 03/05/04
Posts: 96
Loc: Salem,Oregon.USA
7 amps per ton and sized per min nameplate
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