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#66263 - 05/28/06 12:45 PM Tonnage conversion  
Sixer  Offline
Member
Joined: Aug 2005
Posts: 265
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.


Sixer

"Will it be cheaper if I drill the holes for you?"

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#66264 - 05/28/06 01:01 PM Re: Tonnage conversion  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
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.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#66265 - 05/28/06 03:01 PM Re: Tonnage conversion  
Sixer  Offline
Member
Joined: Aug 2005
Posts: 265
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.


Sixer

"Will it be cheaper if I drill the holes for you?"

#66266 - 05/28/06 03:07 PM Re: Tonnage conversion  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
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


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#66267 - 05/28/06 03:53 PM Re: Tonnage conversion  
LK  Offline
Member
Joined: Jan 2003
Posts: 1,429
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.


#66268 - 05/28/06 04:14 PM Re: Tonnage conversion  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
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.


#66269 - 05/28/06 08:05 PM Re: Tonnage conversion  
LK  Offline
Member
Joined: Jan 2003
Posts: 1,429
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.


#66270 - 05/28/06 08:09 PM Re: Tonnage conversion  
WFO  Offline
Member
Joined: Sep 2005
Posts: 202
Cat Spring, TX
Might be different depending on if it is a conventional compressor or a scroll compressor.


#66271 - 05/28/06 11:02 PM Re: Tonnage conversion  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
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)


Mark Heller
"Well - I oughta....." -Jackie Gleason

#66272 - 06/04/06 04:54 PM Re: Tonnage conversion  
OreElect  Offline
Member
Joined: Mar 2004
Posts: 98
Salem,Oregon.USA
7 amps per ton and sized per min nameplate


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