Ask Experts Questions for FREE Help !
Ask
    ffurlong's Avatar
    ffurlong Posts: 2, Reputation: 1
    New Member
    		  
    #1

    Feb 26, 2007, 01:50 PM
    Sizing a fuse
    I have a 30 watt heater 240 Vac

    What size fuse should I use?
    Is there a formula?
    nmwirez's Avatar
    nmwirez Posts: 453, Reputation: 20
    Full Member
    		  
    #2

    Feb 26, 2007, 02:19 PM
    What is the branch circuit conductor line size feeding the outlet the heater is going to be connected to?
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
    		  
    #3

    Feb 26, 2007, 02:41 PM
    A 30 watt heater? Or is that a typo?

    In any case, to conform to NEC code for building wiring, the setting for a fuse/breaker and branch circuit wire size shall be no less than 125% of the current draw of a fixed electric heater.
    ffurlong's Avatar
    ffurlong Posts: 2, Reputation: 1
    New Member
    		  
    #4

    Feb 26, 2007, 05:26 PM
    Quote Originally Posted by nmwirez
    What is the branch circuit conductor line size feeding the outlet the heater is going to be connected to?

    The wire is 18ga small panel heater to keep out moisture. Set for 32 deg f
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member
    		  
    #5

    Feb 26, 2007, 08:58 PM
    30 watts/240 volts X 1.25 = 0.15625 amps

    My old Radio Shack catalog shows nothing less than a 1/4 amp. Should at least protect the wires.
    nmwirez's Avatar
    nmwirez Posts: 453, Reputation: 20
    Full Member
    		  
    #6

    Feb 26, 2007, 11:06 PM
    Quote Originally Posted by ffurlong
    The wire is 18ga small panel heater to keep out moisture. set for 32 deg f
    Do not jury rig this heater. It must be connected with UL or CSA qualified fixture cable and connection outlet device to an NEC compliant branch circuit connector interface. A two (2) amp fuse is adequate to hold the load on 6 amp max rated 18 awg 105 deg C wiring. Fuse may blow if using fan motor of unmentioned type and size. Need specs.

    I am only giving my amateur guess from a distance without seeing the components that you are using and I suggest you consult a professional to oversee your project and environment settup for safety.

    Are you sure this is an 240 Vac heater? Radient? Forced air fan? A 750 watt 120Vac variable speed/heat hair dryer would do better.
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
    		  
    #7

    Feb 27, 2007, 03:38 AM
    Since this is for a panel heater, you may be interested in checking NFPA 79 Electrical Standard for Industrial Machinery, 2007 Edition.
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!

Bow Sizing [ 2 Answers ]

How does one determine what size bow to buy? I have noticed many lengths and draw distances. I don't want to spend a lot of money on a bow to find out it is not comfortable to use.

Pump sizing [ 2 Answers ]

I need to size a centrifugel pump for a system I'm installing. Can you please tell me a simple way to size the pump?

Electrical sizing help [ 5 Answers ]

I am currently building a new building. We as the owners have decided to install a diesel back-up generator unit with auto transfer. The building uses well water and therefore requires a water storage tank for the fire suppression sprinkler system. It also will be using a 100 hp 480 volt 3 phase...

Image sizing [ 7 Answers ]

I downloaded a thumbnail image, is it possible to enlarge it without blurring the image? It is in GIF format.

Sizing Furnace [ 2 Answers ]

I'm finishing my basement and I'm trying to identify if my existing furnace is large enough to heat the basement. Here are the details. I have a Trane XE 80 LP furnace with a 100,000 BTU input rating and it's an 80% furnace. My house is 2250 square feet EXCLUDING the basement. I'm finishing 700...

View more questions Search