- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
I thought so too.
kilowatt to amp
- Thread starter global
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The OP says: "appliances rated at 5.4 Kilowatt @ 120/240"
Wouldn't 120/240 , particularly in the US, normally refer to the supply rather than the appliance?
Bottom line - there just isn't enough information in the OP to give a definitive answer.
- Location
- Massachusetts
As far as I know in the US 120/240 indicates a single phase supply system, 240/120 would indicate a 3 phase supply.
Bottom line, I agree.
:smile:
It's amazing how the most simple of questions can get so many responses and even disagreements. My original thought was for the question writter to do a simple web search as someone else suggested. But the conversation that ensued makes me think they have cause to ask the question here since there are so many opinions.
My impression from the OP was that he had two pieces of equipment that he was reading the nameplate information off of. He wants to know what size breaker to feed these with. I have no idea what voltage he has available in the building. We do not know if they are continuous loads or motor loads. But these loads do remind me of kitchen equipment.
The notation on the equipment of 120/240V means you have the option to connect the equipment to either 120V or 240V. Single phase is implied. The amperage is different for each voltage.
#1 @ 120V = 45A load with min 50A breaker.
#1 @ 240V = 22.5A load with min 25A breaker.
#2 @ 120V = 40A load with min 40A breaker. (larger is suggested)
#2 @ 240V = 20A load with min 20A breaker. (larger is suggested)
My impression from the OP was that he had two pieces of equipment that he was reading the nameplate information off of. He wants to know what size breaker to feed these with. I have no idea what voltage he has available in the building. We do not know if they are continuous loads or motor loads. But these loads do remind me of kitchen equipment.
The notation on the equipment of 120/240V means you have the option to connect the equipment to either 120V or 240V. Single phase is implied. The amperage is different for each voltage.
#1 @ 120V = 45A load with min 50A breaker.
#1 @ 240V = 22.5A load with min 25A breaker.
#2 @ 120V = 40A load with min 40A breaker. (larger is suggested)
#2 @ 240V = 20A load with min 20A breaker. (larger is suggested)
- Location
- Massachusetts
That would mean it uses both, just like an electric dryer or range is rated 120/240.
Again we can not determine the correct OCPD with the information provided.
- Location
- Massachusetts
Actually I will change that to it could mean either, we need more info.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Plain and simple, there is not enough information to provide a definitive answer.
There has been a lot of good input here to show just how this topic needs to have more detail for the proper answer.
Fun to watch how this thread developed though...:grin:
Good to see that at least three of us now agree on that point.
:wink:
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Finally, some sanity here.
The OP failed to state where he is and what his supply voltage is. Granted, this is primarily a North American based forum since it s based on the US NEC, but we all know that people from other countries frequent here. Without that additional info, there is no way to determine anything useful here with certainty, beyond what Mr. Bill said. If the supply is 120V, it is the higher number, if it is 240V, it is the lower number.
I see a lot of newer appliances now coming with this kind of rating, because they are essentially saying that they are suitable for 120 OR 240V supply, 50/60Hz, making them universally applicable to markets in the US and other parts of the world. What these manufacturers are doing now is running the internal motors, controls, elements etc. on DC and using a universal switching power supply that can take any input voltage from 180 - 265VAC. So in order to not have a 10 inch square nameplate to state every possible combination of voltages and current, they just state the kW rating and leave it to the installer to figure it out.
So to be absolutely sure, the OP must determine the supply voltage AND the power input configuration of the appliance; i.e. 1 hot line and a neutral coming into it or two hot lines, with or without a neutral? If there is only 1 hot line coming in, and he is in North America where that would be 120V, then he has to use the higher numbers. But if it takes 2 hot lines (or can be configured to do so), and he is in NA, then he can use the 240V values. But if he is in an IEC country, then 1 hot line and a neutral would be 230V ad he would use the lower values.
Bottom line, not enough info.
I dug thru the UL web site about nameplate markings and found this.
Since no indication of '3W' or '3ph, 4W' was indicated with the nameplate I'll assume the equipment can be connected to 120V or 240V. And if connected at 240V it does not require a neutral connection.
No, but we can determine the minimum, which may or may not be correct. Or at the very least answer how many amps for the connected load.
- Location
- Massachusetts
We just see it differently Mr Bill. :smile:
- Location
- Massachusetts
Is that an acceptance of defeat or do you simply mean 'agree to disagree'?That's just too diplomatic. :wink:
Well at best it was agree to disagree, I actually typed up a detailed reply, refuting each of your points but trashed it when I remembered this whole thread has been nothing but personal opinions.
Here is what we know.
Based on that alone I do not believe we have enough to guess at the answer.
Holy Calculations Batman, did we just complicate a cheese sandwich to the point that we no longer can tell if it is made of cheese or tuna? While I agree that we can not determine the correct OCPD based on te OP's given information we can surely agree that E=IxR can't we?
5.4 KW/240= 22.5 amp connected load
4.8 KW/240= 20.0 amp connected load
Let's go with the remote possibility that it is in fact a 3-phase load
5.4 KW/(240 x 1.732)= 12.99 amp connected load
4.8 KW/(240 x 1.732)= 11.55 amp connected load
The contention that we must use 120 as the voltage for this calculation is just plain wrong. The appliance is rated at 120/240 volts so 140 is correct voltage to use in calculations relating to the appliances in question. I'll go ahead and say it, most of us have read between the lines and know (or assume, if you prefer) that the OP is talking about a household range, oven, or cooktop and a household clothes dryer, he just hasn't said it.
5.4 KW/240= 22.5 amp connected load
4.8 KW/240= 20.0 amp connected load
Let's go with the remote possibility that it is in fact a 3-phase load
5.4 KW/(240 x 1.732)= 12.99 amp connected load
4.8 KW/(240 x 1.732)= 11.55 amp connected load
The contention that we must use 120 as the voltage for this calculation is just plain wrong. The appliance is rated at 120/240 volts so 140 is correct voltage to use in calculations relating to the appliances in question. I'll go ahead and say it, most of us have read between the lines and know (or assume, if you prefer) that the OP is talking about a household range, oven, or cooktop and a household clothes dryer, he just hasn't said it.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Ah, Ohm's Law and Watt's Law. :wink:
peter d
Senior Member
- Location
- New England
Does any one know the formula to convert from jiggawatts to kilovars by any chance?
steelersman
Senior Member
- Location
- Lake Ridge, VA
It's single phase. Just like that neutral in that powerpoint presentation was a neutral and not a ground. Now I'm beginning to understand why you thought it was a ground.
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