Maximum wattage allowed for 110 vac outlet

[PNA]

We have seen some 1650 watt heaters that run on 110 vac.
That is 15 amps of draw.

I thought legally you could only have 12 amps of current draw on a standard outlet. i.e. 12 amp vacuum cleaner

Unless you installed 12 ga. wiring and 20 amp breaker.

Is this wrong?

Paul

 

[waross]

In the US and Canada;
The maximum continous current allowed is 80% of the breaker rating. The voltage divisor to be used is 120.
1650/120=13.75 Amps.
Your heater may not be approved or it may require a 20 amp circuit. The cord end may have been changed from a 20 amp cap to a 15 amp cap to facilitate use on a 15 Amp circuit.
respectfully

 

[PNA]

Thanks

It is an imported heater and i dont understand how this company can legally sell it with a standard plug

Regards

Paul

 

[peebee]

Assuming you're not overloading your circuit breaker (ie, you have nothing else on the circuit), it's probably OK to plug your heater in. If it's UL listed and it has a 15A plug, it's definitely OK to plug your heater in.

Most likely, your heater is not a continuous load as defined in Article NEC 100 (max current expected to last for 3 hours or more). Breakers and branch circuits must be rated for 125% of continuous plus 100% of noncontinuous load per Article 230.

Noncontinuous load, 15A receptacle:
15A / 100% = 15A
15A x 120V / 100% = 1800VA

Continuous load, 15A receptacle:
15A / 125% = 12A
15A x 120V / 125% = 1440VA

Of course, if your heater was UL listed with a 20A plug on it, and it's fed from a 20A breaker & 20A receptacle, then you could provide 2400VA noncontinuous / 1920 continuous from your receptacle and you could run the heater non-stop.

There are other possibilities -- that UL has determined that your 1650W heater is safe to run with a 15A plug, or that your heater really only draws 1440VA and the rating shown is wishful thinking (ie, marketing).

 

[PNA]

Thanks again!

with line voltage varying plus or minus 5% or 10%, it is cutting it close.

Paul

 

[peebee]

You might want to double check that you have a UL label on there. And check for any goofy Chinese-translation-type errors on that label......

 

[PNA]

ul listed
made in europe

 

[dpc]

I agree with peebee: If UL-listed, I'd feel OK about plugging it in. BUT.... there is probably more than one receptacle on this 15 A or 20 A breaker. The UL-label doesn't mean that you can't overload the circuit and cause the breaker to trip.

 

[PNA]

thankyou everyone

Paul

 

[CJCPE]

If the nominal system voltage is 120V, a 1650 watt heater would draw 13.75 amps. Given that marketing people like large numbers, the 1650 watts is probably calculated based on the highest conceivable voltage, perhaps 126V or higher. That would make the resistance 9.62 ohms or more and the current at the 120V nominal system voltage 12.5 amps or less.

 

[PNA]

actually it has a 1600 watt heating element in it
the other 50 watts is for a small fan

 

[waross]

The Canadian Code specifies the voltage figure to be used for calculations as 120V.
The Canadian Code specifies a maximum of 15 amp x 80% x 120 volts = 1440 watts or Volt Amps. on a 15 amp breaker.
I believe the NEC is similar.
I have seen offshore equipment aproved for a 20 amp circuit with the cord end changed to a 15 amp cord end. It's nopt legal but it is done. You can take it up with a local electrical inspector if you don't mind taking the chance that your heater may be declared unusable on a 15 amp circuit. No problem if you have 20 amp circuits available.
respectfully

 

[itsmoked]

Can it be the peak watts? So that you know what the maximum you need is. The average watts could be less. They could always cycle part of the element or force the heater off 10% of the time in an hour.

Does the heater act unusual in any ways like this PNA?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

Lots of hair dryers and other small heating appliances are now being marketed at 1650 Watts, the theoretical limit of a 15A household circuit based upon that code rule about non-continuous loads. The average consumer would have no idea that they might be overloading the circuit, but that doesn't stop them from buying them, because "That must be better than the 1500W version!" My wife bought a new hair drier recently and when she plugs it in to the bathroom outlet while the lights are on (6 x 60W bulbs), the breaker trips. I told her she needs to learn to dry her hair in the dark, but that should be OK because it dries ever so slightly faster with that extra 150W!

JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376

 

[PNA]

Its too bad it has to be that way.
I would hate to see fires and other unfortunate things happen. With how stringent and crazy some labels are, it is surprising these appliances must be plugged into a higher rated circuit, and isolated at that.

What is the different between hookup up an electric dryer rated to operate on a 40 amp 220 circuit?

Should the hairdryer be made to operate on a 20 amp 120 circuit? Plugs, outlets and 12 ga wire are readily available for this application.

Even worse is trying to explain it to the family, that the girls cant be buying and pluggin in stuff like that at our house. Or it will be dark permanently.

Regards

Paul

 

[peebee]

I agree with some of the other posts above... You state 1600w heat + 50w fan, but don't indicate the voltages associated with that data. It would not surprise me at all if these power ratings are based on a 130V supply (which would be a reasonable thing to do if you wanted to call your heater "heavy-duty" -- but could also be reasonably called "marketing").