Ask Experts Questions for FREE Help !
Ask
    exak's Avatar
    exak Posts: 5, Reputation: 1
    New Member
    		  
    #1

    Oct 13, 2008, 03:32 AM
    Code for a 240 volt heating circuit ?
    Hello I am installing one 240 volt circuit to my bedroom and bathroom and the heater in the bed room is 1600 watts. The heater in the bathroom comes pre wired for 900 watts but can be converted to 1800 watts. So my question is do I wire the circuit for 2500 watts or 3400 watts, one being a 15 amp circuit or the other being a 20 amp circuit
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
    		  
    #2

    Oct 13, 2008, 04:13 AM
    What do you mean "wire the circuit for 2500 watts or 3400 watts"??

    Run a 20a circuit using 12/2 cable. That is enough for both heaters.
    You can have 3840 watts of electric heat on a 20A/240v circuit.
    exak's Avatar
    exak Posts: 5, Reputation: 1
    New Member
    		  
    #3

    Oct 13, 2008, 11:34 AM

    Heater in the bathroom comes pre wired for 900 watts but can be converted to 1800 watts. So at 900 watts plus the 1600 watts (bedroom heater) that makes 2500 watts or 15 amps. And I could put in a 15 amp breaker. BUT does code require the circuit to be a 20 amp because 1600 watts plus the 1800 watts ( that could be converted in the future even thought now it is 900 watts ) I am using 12/2 wire now next question is if I do use a 20 amp with 2500 watts and 12/2 wire is this wrong because it should be a 15 amp circuit
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
    		  
    #4

    Oct 13, 2008, 02:23 PM
    WHO is saying it must be a 15A circuit??
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
    		  
    #5

    Oct 13, 2008, 04:44 PM
    To answer your question from the other thread.

    Again, you CAN out up to 3840 watts of electric heat on a 20A/240v circuit.
    You can also put 10 watts of electric heat on a 20A/240v circuit if you want.
    IT IS UP TO YOU.
    hedlok's Avatar
    hedlok Posts: 32, Reputation: 2
    Junior Member
    		  
    #6

    Oct 13, 2008, 06:30 PM

    Go easy on him, stan... sounds like you're having a week like I had last week.
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
    		  
    #7

    Oct 13, 2008, 08:25 PM
    Yeah really. You can say that again!
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
    Printers & Electronics Expert
    		  
    #8

    Oct 15, 2008, 05:57 AM
    Exak,

    Stop thinking in Watts! Stanfortyman is trying to get you to understand that amperage is the key to setting up your wiring. For example, if the heater requires more that 20 amp then you must change the cable and the breaker to match the amperage.

    Look on the heater's metal panel. You should see the required amperage for the heater.

    Amperage gates the size of the wire needed. Voltage X Amperage = Watts.

    For example, VAC 240 X 20 Amps = 4800 Watts (Maximum). Always avoid using the max wattage on a household line. Normally you allow up to 80% of allowed amperage on a line. 4800 X .8 = 3840 Watts. Or shown another way, 20 amps * .8 = 16 amps. 240 X 16 = 3840 Watts.

    That's the wattage you should not exceed. Please note that that is the what Stan has been trying to explain to you from the git-go.
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
    		  
    #9

    Oct 15, 2008, 06:42 PM
    Quote Originally Posted by donf View Post
    For example, VAC 240 X 20 Amps = 4800 Watts (Maximum). Always avoid using the max wattage on a household line. Normally you allow up to 80% of allowed amperage on a line. 4800 X .8 = 3840 Watts. Or shown another way, 20 amps * .8 = 16 amps. 240 X 16 = 3840 Watts.
    Don, just so you know. Electric heat MUST be figured at the 80% maximum for a circuit.
    sckneu's Avatar
    sckneu Posts: 3, Reputation: 1
    New Member
    		  
    #10

    Feb 18, 2010, 08:04 AM
    Hi everyone -

    So am I understanding this correctly?

    I have several heaters I am installing:

    (1) 6' (1500w / 6.3 Amp)
    (2) 30' (500w / 2.1 Amp each / 1000w 4.2 Amp total)
    (1) 4' (1000w / 4.1 Amp)

    Can I put this all on the same 20 Amp, two pole breaker at 240 V using 12-2 wire?

    Thanks!
    sckneu's Avatar
    sckneu Posts: 3, Reputation: 1
    New Member
    		  
    #11

    Feb 18, 2010, 08:08 AM
    Quote Originally Posted by sckneu View Post
    (2) 30' (500w / 2.1 Amp each / 1000w 4.2 Amp total)
    Whoops - should be 30" not 30'!
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
    		  
    #12

    Feb 18, 2010, 08:14 AM

    A 20 Amp 240 Volt heat circuit can have 3840 watts, your's totals 3500 watts, so your covered.
    sckneu's Avatar
    sckneu Posts: 3, Reputation: 1
    New Member
    		  
    #13

    Feb 18, 2010, 08:17 AM
    Quote Originally Posted by tkrussell View Post
    A 20 Amp 240 Volt heat circuit can have 3840 watts, your's totals 3500 watts, so your covered.
    Hi and thanks for the quick reply!

    Does it matter how long the runs are for the 12/2 wire? From the thermostat, the longest run would be about 30' to the farthest heater, taking in to account having to snake the wire up/down/around.

    Thanks again!
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
    		  
    #14

    Feb 18, 2010, 08:33 AM

    No, the footages you are dealing with are not an issue.
Not your question? Ask your question View similar questions
 

Question Tools Search this Question
Search this Question:

Advanced Search

Add your answer here.


Check out some similar questions!

New 250 volt circuit, no grounding bar in main panel [ 4 Answers ]

Hi, I have searched for this answer but I can't find a clear answer for a rookie. I am adding a 250v/20amp circuit to my main panel for a window air conditioner. I have a newer Murray main panel that was installed by an electrician, but its an old house and all the outlets are 2 prong type. So I...

30 amp, 120 volt circuit ? [ 3 Answers ]

Does the electrical code allow for a 30 amp, 12 volt circuit with 15 amp outlets? Here is the reason I ask. I have a technical resource (computer geek) asking for a 30 amp circuit running 120 volts in order to power up a individual computer devices. Each device would be plugged into its own...

What is the hot wire in a typical 120 volt circuit [ 5 Answers ]

What is the hot wire in a typical 120 volt circuit

12 volt circuit in Travel Trailer [ 2 Answers ]

In my small Trailer I have three 12 volt circuits coming from the power center. One circuit blows the fuse as soon as the battery is connected. I thought I had a short somewhere in this circuit so a placed a test light in place of the fuse and thought that with everything on that circuit shut...

View more questions Search