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Old 11-26-2012, 06:36 PM   #71
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If we have trouble with a current draw we just run a heavy duty extention cord out to the electric post and plug into the 20 amp recepticle and plug the heater into the other end.
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Old 11-26-2012, 08:23 PM   #72
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Wattage & Miscellaneous Details

This ex-Ham [from age 12] wired our new House to Code. With that in mind, here's a few details. I use 2 - 1,500 Watt Heaters intermittently to heat the entire super-Insulated, ~1,750 sq. ft. House, since I've not yet connected the Radiant Floor, powered by an Electrical Hot Water Heater.

1. Assuming 115 VAC [vs. 110 VAC or 120 VAC], 1,500 Watt Heaters draw ~13 Amps. 750 Watt Heaters draw ~6.5 Amps. For the sake of argument, a 1,500 watt and 750 Heater operated simultaneously would draw ~19.5 Amps.

Lower Park Pedestal Voltage causes the inverse of higher current to be drawn. Since Breakers open off of current, Breakers operated right at their limit might work in some situations, or at some temperatures, but not in other scenarios.

2. 2 - 1,500 Watt Heaters would draw ~26 Amps. Along with other Coach 'background' electrical draw in addition to this, it's easy to see why a Park Pedestal 30 Amp Breaker might open.

3. If deemed necessary, once the wiring of any given Coach is figured out, I would add several 15 or 20 Amp, breakered, different-colored Receptacles that bypass Inverter and other Electronics. Or, as mentioned above, use 20 Amp Receptacles with the 'T' Neutral [left-most] Slot to distinguish them. There's a lil Hot Tub Breaker Box that holds several, additional Breakers if there's no Breaker Box room elsewhere. Note that there's '1/2 size' [width] Breakers, too, for retrofitting additional Breakers safely if Breaker Box space is tight. Always use ONLY the same Manufacturer and the same Series of Breakers.

The separate, adequate Extension Cord run out to the Park Pedestal works, too.

4. Some Appliances have an 'inrush' current surge, and can trip Breakers intermittently as they require extra current only at turn on. Microwaves and Blenders/Food Processors come to mind. This can be aggravating to track down because Coach Breakers seem to work some times with other Electrical Loads turned on, but not at other times.

5. 12 Gauge [20 Amp] or 16 Gauge [15 Amp] Romex and Wire ratings are intentionally conservative. They actually can carry more current DEPENDING on temperature and whether they're in bundles, etc.. I've never heard of this ~80% Duty Cycle concept mentioned above. 15 Amp Breakers and Wire can carry that Load continuously, at least as I ever learned it, and as my Electrical Contractor Pal taught me the fine details of.

AWG Wire Charts

As some other A-R, safety-minded Contributors mention here, I would add intrinsically-safe Coach Receptacles [if necessary] that simply prevent any chance of overheating and failure. Then, Heaters can be chosen based on size; cost; style, and other factors. We have a Dog, so I realize Heaters can be knocked over accidentally. I stabilize them accordingly on a square of inflammable Tile in my lil Trailer, and keep Fire Extinguishers and Smoke Detectors in good order.

I plumbed our Colorado Solar House for Propane, but then changed over major Appliances to Rural Grid-supplied Electricity. Per 1,000 Heating BTUs generated, Electricity is cheaper than Propane. However, this depends on local Electricity cost, along with Taxes and Fees tacked on.

An important detail: virtually 100% of Electricity is converted to heat by Electrical Heaters. Although I don't see a Conversion Efficiency for, say, Atwood Propane Furnaces on line, this Conversion Efficiency to Heating BTUs is significantly less. Heat goes out the Exhaust Vent.

From the Website linked below:

'Based on these calculations, I am getting costs of:

Propane: $0.0315 / 1k BTU
Oil: $0.0284 / 1k BTU
Electric: $0.0239 / 1k BTU.

I was always told that electric heat is going to be much more expensive than oil or propane, but this math is not showing this to be the case based on costs in our area.'

House Heating ~ Electrical vs. Propane Calculations ~ 2012
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Old 11-27-2012, 02:31 AM   #73
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will; In your post from yesterday you stated that most MHs the micro is wired thru the inverter and not to use this curcuit. I have found no Mh that the micro is wired thru the inverter as mine is not. Just like the 120 to the water heater and refer (unless you have a residentual model) the load would be to great for a 2kw inverter if used all at once. The micro curcuit that I use is a dedicated 20 amp curcuit just for the micro. I have also thought about disconnecting the engine block heater and using that curcuit as the switch is on the bed pedistal and a good place to plug in a heater. Everything else you have said is very good sound advice and some newer MHs may have the micro wired thru the inverter
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Old 11-27-2012, 06:22 AM   #74
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will; In your post from yesterday you stated that most MHs the micro is wired thru the inverter and not to use this curcuit. I have found no Mh that the micro is wired thru the inverter as mine is not. Just like the 120 to the water heater and refer (unless you have a residentual model) the load would be to great for a 2kw inverter if used all at once. The micro curcuit that I use is a dedicated 20 amp curcuit just for the micro. I have also thought about disconnecting the engine block heater and using that curcuit as the switch is on the bed pedistal and a good place to plug in a heater. Everything else you have said is very good sound advice and some newer MHs may have the micro wired thru the inverter
My coach is a 98, and the micro is wired thru the 2500 watt inverter.

I think it would be simpler to do what I recommended in my earlier post.

If you use the circuit breaker for the block heater as a switch, the CB itself can be damaged over time.

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Old 11-27-2012, 07:02 AM   #75
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This thing has gotten out of hand.

Inverters
If the inverter relay (contactor) is always in the bypass position, it will pass its rated current without a problem. The problems will come about if the inverter is going from bypass to inverter conditions repeatedly. That should never happen when connected to shore power or generator. If it does, something is wrong.

It should go without saying that an electric space heater should never be connected to any inverter circuit when the inverter can invert 120 volts AC from 12 volts DC. The inverter side must be off.

Just consider that some have suggested using the microwave connection as a precaution. In almost every case the microwave connection will be fed by the inverter. Also consider that the microwave is a very high amp draw device. Since mine is a convection/microwave, it runs for long periods of time and without any problems -- sometimes several hours.

Unless there is something wrong in the system, the closed bypass contactor in the inverter contacter will never even feel the current going through it in the bypass mode.

Heater Type
No matter what heater you use, a watt of electricity produces 3.41 btu. You'll get no more or less heat from any heater with the same watt rating. The temperature of the output of the heater is a function of how much air is circulated over the element -- not what kind of element is used. More air, lower outlet temp, less air, higher temp.

Any heater with UL approval is safe to use so far as electrical things are concerned. Fire hazards only come about when something goes wrong with the installation -- it turns over and the element comes in contact with flammable material, etc.

Heaters do differ in safety features. It should turn off if it overturns or if it exceeds its high limit temperature setting.

In addition, it should never be placed on flammable material -- like rugs. Use an insulator like a glass plate, etc. under the heater.

Other than that get any heater you want.

Wil
Thankyou will ; these forums are full of myths and misinformation with a little scare tactics by people who got their info from rumor. You are correct!!!
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Old 11-28-2012, 12:16 AM   #76
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I'm almost afraid to ask this because I will look (and am) so clueless. But here goes. How do you know which plug is connected to the microwave if the microwave is built in? I don't see where I would plug in a heater and know it's the microwave plug. Someone please HELP!!!
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Old 11-28-2012, 07:22 AM   #77
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Disconnect the shore power. Start the inverter. See if the microwave works. If it does, it comes from the inverter.

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Old 11-28-2012, 12:27 PM   #78
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Disconnect the shore power. Start the inverter. See if the microwave works. If it does, it comes from the inverter.

Wil
This is crazy. I can't see where the microwave is plugged! Where do I plug the heater?
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Old 11-28-2012, 02:38 PM   #79
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There is most likely a cabinet on one or both sides of the microwave over. The outlet is most likely in one of those cabinets.

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Old 11-28-2012, 06:43 PM   #80
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will; In your post from yesterday you stated that most MHs the micro is wired thru the inverter and not to use this curcuit. I have found no Mh that the micro is wired thru the inverter as mine is not. the load would be to great for a 2kw inverter if used all at once. some newer MHs may have the micro wired thru the inverter
In my '96 coach the over the range microwave is plugged into an inverter powered outlet.
The micro is usable for short durations, powered by the 2000watt Xantrex Freedom 20 inverter.
When on shore power I use only one 1500 watt space heater in an inverter outlet, (no microwave use, no other high watt appliances in any other inverter outlets).
A second 1500 watt heater can be used in any outlet that does not run through the inverter.
I have added an outlet onto the Splendide circuit that can be used for a 1500 watt heater when the dryer is not being used.
The cord from the shore power 20A outlet to a 1500 watt heater is a simple safe solution.

Someone suggested only operating space heaters on LOW, (750 watts) to be SAFE.
To that I say, "GET REAL, If you don't mind being COLD, you can be even SAFER if you don't turn the heaters ON at all"! LOL
Personally, I turn on space heaters because I want HEAT!

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Old 11-28-2012, 07:47 PM   #81
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will; In your post from yesterday you stated that most MHs the micro is wired thru the inverter and not to use this curcuit. I have found no Mh that the micro is wired thru the inverter as mine is not. Just like the 120 to the water heater and refer (unless you have a residentual model) the load would be to great for a 2kw inverter if used all at once. The micro curcuit that I use is a dedicated 20 amp curcuit just for the micro. I have also thought about disconnecting the engine block heater and using that curcuit as the switch is on the bed pedistal and a good place to plug in a heater. Everything else you have said is very good sound advice and some newer MHs may have the micro wired thru the inverter
Dave?your a retired RV tech? I find it hard to beleive you dont realize Micro waves are wired through inverters?? My 1997 2002 and now 2008 units all work the micro through the Inverter
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Old 11-29-2012, 10:09 AM   #82
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If you plug the heater into your microwave outlet, you should turn the heater off each time you run the microwave. This is not an ideal situation.
I've spent several cold winters in my motorhome. If electric is free, I use two space heaters. One is plugged into one of the motorhome 110V outlets, and the other is plugged into a heavy 10 gauge extension cord run through the window direct to the power pedestal. This insures you can run both heaters on hi or low and not overload the motorhome circuits when additional electrical loads are added.
If you are going to be living in your motorhome during winters, the best method is to purchase a motorhome with an Aqua Hot system. Aqua Hot can use electrical power or diesel to provide heat and hot water and does not dry out the interior.
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Old 11-29-2012, 11:09 AM   #83
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If you plug the heater into your microwave outlet, you should turn the heater off each time you run the microwave. This is not an ideal situation.
I've spent several cold winters in my motorhome. If electric is free, I use two space heaters. One is plugged into one of the motorhome 110V outlets, and the other is plugged into a heavy 10 gauge extension cord run through the window direct to the power pedestal. This insures you can run both heaters on hi or low and not overload the motorhome circuits when additional electrical loads are added.
If you are going to be living in your motorhome during winters, the best method is to purchase a motorhome with an Aqua Hot system. Aqua Hot can use electrical power or diesel to provide heat and hot water and does not dry out the interior.
I have 50 amp circut.It also has 2 -30 amp circuts run through the inverter/converter system.I run fridge,hot water,electric heater,micro all together and nary a problem.I think the problems talked about on here regarding this issue are old 30 amp units not the newer 50 amp/large inverter type systems
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