Heaters limited??

[brother]

where is this found in the NEC 2008 where 120volt heaters are limited by the electrical code to 1500 watts??

In the above example of heater sizing, a 240 square foot room had a heat need of 2400 watts. If that were the room you were purchasing a heater for, you would have no choice other than to use a 240 volt heater, since 120 volt heaters are limited by the electrical code to 1500 watts.

 

[rwreuter]

can't give you a code ref., someone else here maybe able to.....but heaters are to be calculated as a continous load. which in essence limits them (120v) to 1500watts.

sound about right?

 

[480sparky]

where is this found in the NEC 2008 where 120volt heaters are limited by the electrical code to 1500 watts??

210.21(B)(2) maybe?

 

[augie47]

There may be such a rule, but my guess is that it is more a "rule" of supply and demand. The space heaters are sold primarily as portable units to be "plugged into any household outlet" and 1500 watts is about the limit where that is possible.
Higher wattage units would normally require added circuitry which, for the wattage, is generally less expensive on higher voltages.

 

[brother]

can't give you a code ref., someone else here maybe able to.....but heaters are to be calculated as a continous load. which in essence limits them (120v) to 1500watts.

sound about right?

Is there a reason why a 120 single pole 30 amp breaker cannot be used for a single outlet for fixed electric space heater?? for example, a 2000watt heater at a 120 volts, comes to 16.66 amps X 1.25 =20.825 amps.

so Im still at a loss at what they mean a 120v heater is limited to 1500 watts. heres the article.

http://www.epinions.com/content_2567086212

 

[iwire]

Is there a reason why a 120 single pole 30 amp breaker cannot be used for a single outlet for fixed electric space heater?? for example, a 2000watt heater at a 120 volts, comes to 16.66 amps X 1.25 =20.825 amps.

so Im still at a loss at what they mean a 120v heater is limited to 1500 watts. heres the article.

http://www.epinions.com/content_2567086212

Consider the source.

 

[Smart $]

There may be such a rule...

Perhaps...

210.6 Branch-Circuit Voltage Limitations. The nominal
voltage of branch circuits shall not exceed the values permitted
by 210.6(A) through (E).

(A) Occupancy Limitation. In dwelling units and guest
rooms or guest suites of hotels, motels, and similar occupancies,
the voltage shall not exceed 120 volts, nominal,
between conductors that supply the terminals of the following:
(1) Luminaires
(2) Cord-and-plug-connected loads 1440 volt-amperes,
nominal, or less or less than 1⁄4 hp
?

 

[augie47]

well I'll be...............
I absolutely must buy me a copy of that book one day :grin:




and actually read it



how embarassing.........

 

[Smart $]

well I'll be...............
I absolutely must buy me a copy of that book one day :grin:




and actually read it



how embarassing.........

Ahh! You shouldn't be. This one relies solely on memory, and is a good test question on familiarity with the code book.

Present the question or problem as VA or W limitation based on voltage and it stumps most, because the requirement is voltage limitation based on VA.

 

[iwire]

Ahh! You shouldn't be. This one relies solely on memory, and is a good test question on familiarity with the code book.

Present the question or problem as VA or W limitation based on voltage and it stumps most, because the requirement is voltage limitation based on VA.

The code section you posted does not prohibit 2000 watt heaters in dwelling units or limit them to 120 volts.

 

[LarryFine]

The code section you posted does not prohibit 2000 watt heaters in dwelling units or limit them to 120 volts.

Agreed. It merely states that you are permitted to use a higher voltage with loads greater than 1440va if you wish.

 

[rwreuter]

when i made my post i went back to try and edit it to ask if it was cord and plug connected or hardwired units.

system said i had to ask the administrator even when the edit button was present.

funny how you know that sometimes you know the rules but can't remember the ref. or whys.

 

[Smart $]

The code section you posted does not prohibit 2000 watt heaters in dwelling units or limit them to 120 volts.

I did not say it did (or didn't). I simply quoted code ("rule") that was likely at the core of the issue.

Agreed. It merely states that you are permitted to use a higher voltage with loads greater than 1440va if you wish.

More correctly, regarding cord-and-plug-connected loads, you must use a higher voltage with loads greater than 1440va. It makes no such limitation for hard-wired loads.

 

[Volta]

I did not say it did (or didn't). I simply quoted code ("rule") that was likely at the core of the issue.



More correctly, regarding cord-and-plug-connected loads, you must use a higher voltage with loads greater than 1440va. It makes no such limitation for hard-wired loads.

You mean the 1500w 120v heater isn't allowed?:roll:

 

[LarryFine]

More correctly, regarding cord-and-plug-connected loads, you must use a higher voltage with loads greater than 1440va.

If you're talking about the blue text in Smart's quote of 210.6(A)(2), it only says that loads of 1440va or less cannot be supplied by more than 120v, not that greater loads must be.

 

[LarryFine]

You mean the 1500w 120v heater isn't allowed?:roll:

I've seen 1850w hair blowers.

 

[Volta]

I've seen 1850w hair blowers.

And 2200w in a salon commercially too! ( Service call for an overheating circuit, go figure [Doesn't a duplex mean two hair dryers at once???] ).

And UPS units with L5-30's, of course.:roll:

 

[brother]

Thanks for the info, I wonder what hp the motor is in the heaters. there is a limitation on them as well.

 

[Smart $]

You mean the 1500w 120v heater isn't allowed?:roll:

If you're talking about the blue text in Smart's quote of 210.6(A)(2), it only says that loads of 1440va or less cannot be supplied by more than 120v, not that greater loads must be.

I've seen 1850w hair blowers.

And 2200w in a salon commercially too! ...

Yeah, that was my oops. Larry said what I thought I meant.

 

[Copperclad]

do what?

do what?

There may be such a rule, but my guess is that it is more a "rule" of supply and demand. The space heaters are sold primarily as portable units to be "plugged into any household outlet" and 1500 watts is about the limit where that is possible.
Higher wattage units would normally require added circuitry which, for the wattage, is generally less expensive on higher voltages.

Please explain this further......
your saying that a 1500w heating element would be less expensive to operate on a higher voltage?