Portable electric heater questions

[sliderule]

When it comes to various portable heaters rated 1500 watts that plug into a 15 amp 120 volt receptacle, what NEMA, UL, etc. standards do they have to comply with?

When they are rated and labelled 1500 watts, how close to 1500 watts do they have to be when operated at 120 volts? Are they permitted to be much lower than 1500 watts?

If they are rated at a nominal 120 volts, is this at the terminals on the element(s) inside the heater or is the voltage as measured at the cord's plug? Many of these heaters have 16 ga. cords and will have a voltage drop of .6-.8 volts at the element's terminals.

I took the only 1500 watt portable heater ("cube" style) we have at home and I measured the current draw and voltage at the heater elements and re-calculated it at 120 volts and got 1546 watts. Do portable heaters perhaps have a max. rating of 1500 watts if voltage is measured at the receptacle they're plugged into? The reason I ask is that someone claimed that any portable heater they've measured draws substantially less than it's rating.

On a related note, my wife has a hair dryer that is rated 1875 watts which is a FLA of 15.6. Have not measured the current to see how it compares. Are manufacturers able to artificially inflate wattage ratings on portable appliances? A hair dryer is different than a heater tho. and normally would only run for minutes.

 

[petersonra]

I think UL actually rates them at 125 V.

There is almost certainly a UL listing mark on the heater. You should be able to tell from that what standard it was made to.

 

[sliderule]

I think UL actually rates them at 125 V.

There is almost certainly a UL listing mark on the heater. You should be able to tell from that what standard it was made to.

Well duh, it says on the label it complies with UL 1278... I can't seem to find UL 1278 on the internet without purchasing it tho.

I thought UL covers primarily safety aspects or is that incorrect? I thought NEMA requires portable equipment, appliances and devices to operate at a nominal rating of 120 volts? The label on the heater says 120 volts.

 

[petersonra]

Well duh, it says on the label it complies with UL 1278... I can't seem to find UL 1278 on the internet without purchasing it tho.

I thought UL covers primarily safety aspects or is that incorrect? I thought NEMA requires portable equipment, appliances and devices to operate at a nominal rating of 120 volts? The label on the heater says 120 volts.

I think that UL still rates them at 125 V.

 

[petersonra]

I think that UL still rates them at 125 V.

It appears I am incorrect.

63.1 A heater shall be rated in amperes, volt-amperes, or watts and also in volts; and may be rated for
alternating current only. The rating shall include the number of phases if the heater is designed for use on
a polyphase circuit, and shall include the frequency if necessary because of motors, relay coils, or other
control devices. The voltage rating shall be any appropriate single voltage or voltage range such as: 100
– 120, 208, 220 – 240, 254 – 277, 440 – 480 and 600

 

[sliderule]

I found UL 1278 online (dated 2008). What an incredibly long list of various safety requirements for a manufacturer to have to meet.

The only thing covering wattage that I could see is "power input to a heater shall not be more than 105 percent of its marked rating." I could not see anything relating to a manufacturer being allowed to install a heating element(s) that provides a lower output than what is on their label on a heater. Perhaps some manufacturers lower element wattage somewhat to be able to comply with max. internal temp. requirements?

It appears by UL 1278 that voltage is required to be for the wattage that is listed on the heater's label. Could not see anything that specifies a voltage of 120 volts only and appears to allow a range of 100 to 120 volts as long as it is on the label. The label on the heater I have says 120 volts.

This UL standard also seems to refer to heater output as it's voltage is measured at it's cord's plug and not at the element terminals inside a heater, which would make sense.

I still thought there is a voltage requirement under a NEMA standard that requires various equip., appliances, etc. to operate at a nominal system system voltage as per C84.1 (120 volts)?