Replies

1. 
   woodworker57 | Oct 26, 2008 05:04am | #1

   Handle what?

1. 
   Sphere | Oct 26, 2008 05:22am | #3

   I've a room circut that is carrying 6 outlets, and one cieling light , I have a computer, a plasma TV, and 2 @ 1500 watt space heaters, when the one heater ( oil filled radiator) cycles, the light dims briefly ( 2 @75 watt incandescents).

   I think I'm pushing it..just wondering.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

    

   They kill Prophets, for Profits.

   http://www.youtube.com/watch?v=Dj_oEx4-Mc4

    

1. 
   Biff_Loman | Oct 26, 2008 05:25am | #4

   Power, expressed in watts, is the product of voltage x current (amps). So specifically, somewhere in the territory of 1700 watts. . . Your space heaters aren't drawing their maximum current.

   Edited 10/25/2008 10:26 pm ET by Biff_Loman

2. 
   mmoogie | Oct 26, 2008 05:31am | #5

   Well, volts times amps equal watts, so one 1500 watt heater is drawing 12.5 amps. I'm surprised you can run two of them on a 15 amp circuit at all. I think I heard somewhere that you aren't supposed to run a circuit at more than 80 percent of it's capacity under steady load. Don't know if that's really correct or not, but it so, that's 12 amps.Steve

1. 
   Sphere | Oct 26, 2008 05:42am | #6

   I thought so, thanks. I see I need to rearrange some stuff and add a new circut.

   This house is wired in a cheap fast way, and I re-do a room at a time, this one had me scratching my head.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

    

   They kill Prophets, for Profits.

   http://www.youtube.com/watch?v=Dj_oEx4-Mc4

    

1. 
   BillHartmann | Oct 26, 2008 11:54pm | #16

   Some of those oil filled heaters use variable resistance elements so that they draw less current when they are warmer.So I suspect that is what is keeping the breaker from tripping and/or cycling of the thermostats.Breakers have heating element and bimetallic trip for overloads. Faults (shorts use a different magnetic trip). That have time inverse curve so that for small over loads they take a long time to trip. Faster for larger.Typical curves show that they might hold forever for 130% and for an couple of hours for 150% overload and upto an hour for 200% overload. It has been a while since I looked at one, so I can be sure of the numbers, but the general concept is correct. They will carry a significant overload for a long time.So with the 2 heaters on the one circuit I suspect that you have a continuous overload and that is causing small, but continuous overheating of the wires and breakers. And that in turn while it might not show up immediately you will find damaged insulation in a few years. Speically if this in on holder wiring (such as NM vs the newer NM-B which uses high tempature insulation).Best to split this up.In fact the heaters are large enough for each to be on it's own circuit.But if you don't think that this will be more than a couple of years you can leave one of the heaters on a circuit with the other stuff.In fact where you know that you have.
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

2. 
   Sphere | Oct 27, 2008 12:11am | #18

   Thanks Bill, I have access to the feed and so far it's calm..but I also have  new circut ( this was all done by prev.HO) that can carry the load, it's a 220 I can split off of.

   I'm just looking at worst case heat wise scenario, not flash and poof.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

    

   They kill Prophets, for Profits.

   http://www.youtube.com/watch?v=Dj_oEx4-Mc4

    

2. 
   BillHartmann | Oct 26, 2008 11:39pm | #15

   The 80% factor is for CONTINUOUS loads. And by definition that is anything that is on for over 3 hours.Lighting and general purpose receptacles are not treated as continuous loads as you don't know what combination will be used at any one time.Things like electric WH and baseboard heaters would.But in a case like this at least the portion used by the space heater should be so treated.I would treat them as being 120% of "rating" and any other know stuff at nameplate rating..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

3. 
   highfigh | Oct 26, 2008 01:34pm | #11

   You're pushing it, all right. 2@1500W isn't the output, because there's no such thing as a lossless device, so energy is always wasted as heat and when your voltage drops due to high current draw, everything runs less efficiently, hotter and the durability decreases. When something starts up, the peak current draw drops the voltage and that's why you see the lights dim. Why not change to CFL bulbs? They last a lot longer, are cheaper to use and the light doesn't look like the old ring-style that used to go in old people's kitchens.
   "I cut this piece four times and it's still too short."

1. 
   Sphere | Oct 26, 2008 03:23pm | #12

   Ya know, I have the sprial CFL's almost every where else, but this part of the house stays pretty cold , hence the heaters.

   The CFL's in the kitchen are dim as all get out when ya first fire them up, and we just never got them into the cieling fan/light in this room yet.

   This is the Living Room technically, but we've abandoned the upstairs bedroom till I get the floor installed and are using it as storage area, and the LR is now a bedroom ..long complicated story, but being downstairs the woodstove heat just rises upstairs through the open dog trot, it gets damm chilly downstairs in this room.Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

    

   They kill Prophets, for Profits.

   http://www.youtube.com/watch?v=Dj_oEx4-Mc4

    

1. 
   highfigh | Oct 26, 2008 08:05pm | #14

   It's not elegant, but I'm sure you've seen the zippered plastic curtains used for construction and painting, to keep dust and spray from going into an adjacent room. Sherwin-Williams sells them and others, too, If you put one at the bottom of the stairwell and don't need to go up there often, it might be a good thing to have.You could always put heat lamps in. Nice and toasty.
   "I cut this piece four times and it's still too short."

2. 
   gfretwell | Oct 26, 2008 07:20pm | #13

   Actually 1500w is the output. Electric space heat is one of the few 100% efficient appliances. It doesn't really matter where the loss is. Loss in the line cord is still heat in the room.
   Losses are only important when heat is not your objective.

3. 
   BillHartmann | Oct 27, 2008 12:01am | #17

   Changing the lights in a case like this like empty out all of the stuff in the glove box in a truck that gets 10 mpg in the hopes that it will lighten the weight in the truck and it will get better millage."You're pushing it, all right. 2@1500W isn't the output, because there's no such thing as a lossless device, so energy is always wasted as heat and when your voltage drops due to high current draw, everything runs less efficiently, hotter and the durability decreases. When something starts up, the peak current draw drops the voltage and that's why you see the lights dim."Duh!The purpose of the heater is to HEAT. All of the energy into is comes out as "so called waste" heat. But for resistive loads as the voltage drops they drop LESS current and produce LESS HEAT. And that also includes incandescent lights.And they last longer. That is why 130 volt lights are sold as long life when used on 120 volt systems.It is motor driving equipment that struggles at low voltage. Motors are more of a constant power load. So if the voltage drops they draw more current and produce more waste heat..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

2. 
   woodworker57 | Oct 26, 2008 05:12am | #2

   I think I answered my own question after reading your post more carefully.  If my math is correct,  it should handle 1500 watts ok.   WW 57

3. 
   rasconc | Oct 26, 2008 06:29am | #7

   I believe design is to go to about 75-80% of circuit protection.  One of the real electricians will surely chime in.

   For those who have fought for it Freedom has a flavor the protected will never know.
1. 
   Sphere | Oct 26, 2008 06:49am | #8

   Well, I ain't got no shock and awe so far, so all's good..LOL

   Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

    

   They kill Prophets, for Profits.

   http://www.youtube.com/watch?v=Dj_oEx4-Mc4

    

   Edited 10/25/2008 11:50 pm ET by Sphere

1. 
   maddog3 | Oct 26, 2008 11:48am | #9

   what rasconc said ... give your self some wiggle room on the circuits so the breakers don't run hot, so try running two feeds for your heaters and feed them from A - B and don't stack them.. you want to try to keep some air around breakers that run under a load continuously, and up size wire if you can IOW don't use #14.

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4. 
   highfigh | Oct 26, 2008 01:29pm | #10

   P=IE, so multiply Voltage (E) by Current (I). Also, line voltage has been at least 117V since the mid-'50s, so unless your area has power issues, it should be at least that during off-peak hours.

   Electronics- always precise, never exact.
   "I cut this piece four times and it's still too short."

   
   

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   Edited 10/26/2008 6:36 am by highfigh