Be careful with your space heaters

[Razorback]

Space Heater Misuse in RVs Claim Two Lives

January 8, 2010 by


Two people have been killed, two injured and at least six RVs destroyed in the last three weeks across the U.S. in incidents linked to the use of electric space heaters, according to a posting by the RV News Service.
The winter heating season has arrived, and fire officials say more caution needs to be exercised by those who would take off the chill with space heaters.
Kurt Strey, who serves as fire chief in New Berlin, Texas, recalls the results of a recent travel trailer fire in his jurisdiction. “People who were using space heaters either overloaded it or placed it too close to something combustible,” he said. “A lady who was sleeping inside woke up to a trailer full of smoke and kicked out a window to escape. She narrowly escaped with her life.”
In Florida, a man and his daughter escaped a burning fifth-wheel after their electric space heater began sparking and the rig filled with smoke. An as-yet-to-be identified man in Seminole, Okla., wasn’t so fortunate. Fire officials recovered his body from a travel trailer that had been heated with multiple space heaters

 

[kakampers]

This is why I NEVER leave the electric space heaters on when we leave the unit or when we are sleeping. At night we use ONLY the factory installed furnace...this also helps to make sure the heat reaches the underbelly and keeps it warm overnight....

 

[vangoes]

We just had an incident last weekend with our wiring. The wiring in the junction box under the dining area slide burned completely out. This junction box is for the one outlet in the slide. The only thing on this outlet was a ceramic heater so the circuit should not have been overloaded. What is concerning to me is that the circuit breaker did not trip and the remaining outlets on this circuit remained hot. We are fortunate that the burning was contained within the junction box which is outside the camper so there was no smoke, fire or fumes inside; however, we are now leary of the other circuits within the coach, especially the fireplace circuit. Why didn't the circuit breaker trip and why did the wires burn????

 

[jmgratz]

This is why I NEVER leave the electric space heaters on when we leave the unit or when we are sleeping. At night we use ONLY the factory installed furnace...this also helps to make sure the heat reaches the underbelly and keeps it warm overnight....

We do the same....

 

[caissiel]

The fireplace is also CSA approved and the circuit is dedicated only to it.

 

[Bobby A]

This is why I NEVER leave the electric space heaters on when we leave the unit or when we are sleeping. At night we use ONLY the factory installed furnace...this also helps to make sure the heat reaches the underbelly and keeps it warm overnight....

Ditto that !!!!

 

[JohnDar]

We just had an incident last weekend with our wiring. The wiring in the junction box under the dining area slide burned completely out. This junction box is for the one outlet in the slide. The only thing on this outlet was a ceramic heater so the circuit should not have been overloaded. What is concerning to me is that the circuit breaker did not trip and the remaining outlets on this circuit remained hot. We are fortunate that the burning was contained within the junction box which is outside the camper so there was no smoke, fire or fumes inside; however, we are now leary of the other circuits within the coach, especially the fireplace circuit. Why didn't the circuit breaker trip and why did the wires burn????

What are the specs on the heater? Was it cycling on and off answering it's thermostat or running continuously trying to heat the trailer? A 1500 watt electric heater draws about 13A. That heats up the wires. If they don't get a chance dissipate it, the heat continues to build until the insulation melts. The breaker will not trip unless the wires short to ground.

 

[5erWonk]

After our electric fireplace (DESA) went out last week I am concerned......Upon removal of the rocker switch I found the connectors had over-heated and melted the insulation.

 

[caissiel]

Nice to know, but if they are CSA approved they should be good for continuous use, and so is the wiring being 14Ga. for 15 amps.

 

[JohnDar]

Nice to know, but if they are CSA approved they should be good for continuous use, and so is the wiring being 14Ga. for 15 amps.

According to my CodeCheck booklet (Cliff's Notes for the NEC), after 3 hours of continuous load, wiring loses 20% of its ampacity or ability to carry current without overheating. So, a 14ga, 15A wire drops to 12A. Meanwhile, that 1500W electric heater is still merrily drawing 13A trying to warm the trailer. Thus the heating and breakdown of the insulation. The breaker isn't seeing this heat and without a ground short, it don't care.

14ga., 15A circuits are meant for lighting and light duty use. A 1500W heater running continuous would be safer on a 12ga., 20A circuit. Safer still is using it to temporarily augment the furnace, not replace it.

 

[wdk450]

Electrical Fires

According to my CodeCheck booklet (Cliff's Notes for the NEC), after 3 hours of continuous load, wiring loses 20% of its ampacity or ability to carry current without overheating. So, a 14ga, 15A wire drops to 12A. Meanwhile, that 1500W electric heater is still merrily drawing 13A trying to warm the trailer. Thus the heating and breakdown of the insulation. The breaker isn't seeing this heat and without a ground short, it don't care.

14ga., 15A circuits are meant for lighting and light duty use. A 1500W heater running continuous would be safer on a 12ga., 20A circuit. Safer still is using it to temporarily augment the furnace, not replace it.

John:
Thanks for that tidbit about the reduction in ampacity due to cable loading/heating. In 45 years of working with electricity this is a fact I had never heard of.
It seems over the last 20 years the predominant cause of household fire I hear about, is electrical. I, like others, have expected overload circuit breakers to be all the protection that safety agencies like the NFPA deemed we needed. I have often wondered how well circuit breakers do to protect us after they have aged (they are never checked for this after they are sold), and how well they are individually quality checked at the factory. I have heard that there is a new generation of electronic circuit breakers that besides tripping for overloads, trip if poor connection arcing is detected on the circuits they feed. The supposed drawback is that these new breakers trip for no apparent reason, and the wiring system has to be disassembled/analyzed to find the fault.
Failing electrical connections with current loads has been an area of interest of mine for a long while. I find it really interesting to observe a poor/lightly corroded connection as it heats under current flow, the heat causing more corrosion and resistance over time, in a continuous expanding loop until the connection ultimately melts/fails. Industrial electricians address this by one of the first uses of the infrared thermometers you can now get so cheaply. They would take the cover plates off of the breaker panels while electricity was being consumed in normal use, and look for hot spots at the connections. Now this is done with an infrared camera that takes a picture to identify the hot spots.
Its too bad that RV's don't lend themselves to enclosed conduit/electrical box wiring systems like in current home/industrial construction. The tubes/boxes enclose the wiring in case of an overheating situation (limiting fire), and make it fairly easy to pull in larger wiring if needed.
The only preventatives I can think of for us is awareness of the wiring limitations (especially under continuous maximum load), and inspection/maintainence of the electrical connections. The breaker box is the most centralized/easiest place to routinely check for loose connections. Maybe as a group, we can identify a list of important connection boxes in other places on each model to check. Possibly the factory could advise us on this.
A final idea: Maybe we could add a 20 amp breaker and 12 guage wired outlet (as John Dar suggested) right next to the breaker box specifically for electrical heaters. This would be fairly easy to do and involve the minimum amount of wiring. This location is at the center of my coach, and running fan only on the thermostat could circulate the heat throughout the trailer.

 

[porthole]

14ga., 15A circuits are meant for lighting and light duty use. A 1500W heater running continuous would be safer on a 12ga., 20A circuit. Safer still is using it to temporarily augment the furnace, not replace it.

A final idea: Maybe we could add a 20 amp breaker and 12 gauge wired outlet (as John Dar suggested) right next to the breaker box specifically for electrical heaters.

This is exactly what I did when I went through the trouble to add an outlet on the 3010.

If you are going to go through the trouble of cutting holes, running wire, adding breakers - may as well make it good for something other then charging your phone.

Post #60 of my "And So It Begins" thread.

//heartlandowners.org/attachment.php?attachmentid=5749&d=1259722672

 

[porthole]

I know it would add some cost - but if it was up to me I'd wire trailers under the same rules for boats.

All stranded wire and all crimp connectors.


Hey - on the bigger trailers we already have a start - the Marinco "Big 50" AC inlet on the side of the trailer.

 

[Hamshog]

Hey All,

I've lived in trailers and boats for over 4 years, fulltime(trailers) and liveaboard(boats) in Idaho, Oregon and Washington state during my travelling years in the trade. I've used electric heaters in all the rigs and never had a problem. Knock wood!! I also would never run them on high!! Always two heaters, one in the living area and one in the bedroom. On the boat it was one in the living area and one in the enclosed cockpit. Keep area clear of any combustable items and keep the heaters clean from dust buildup. I'm still useing a heater that I bought back in the early 90's in the bedroom of our current rig..

Be carefull ya'll!!

Regards, Hamshog

 

[wdk450]

Crimp Connectors

I know it would add some cost - but if it was up to me I'd wire trailers under the same rules for boats.

All stranded wire and all crimp connectors.




Hey - on the bigger trailers we already have a start - the Marinco "Big 50" AC inlet on the side of the trailer.

Gang:
I have seen too many roasted crimp connectors in my career. I prefer to add a soldered joint to any crimp connector I encounter in a power (not logic) circuit. Solder enters the metal crystalline matrix on each of the metal surfaces it is applied to making a superior electrical connection, and makes an airtight seal on top of the metal-to-metal crimp connection, which renders it corrosion proof.

 

[vangoes]

According to my CodeCheck booklet (Cliff's Notes for the NEC), after 3 hours of continuous load, wiring loses 20% of its ampacity or ability to carry current without overheating. So, a 14ga, 15A wire drops to 12A. Meanwhile, that 1500W electric heater is still merrily drawing 13A trying to warm the trailer. Thus the heating and breakdown of the insulation. The breaker isn't seeing this heat and without a ground short, it don't care.

14ga., 15A circuits are meant for lighting and light duty use. A 1500W heater running continuous would be safer on a 12ga., 20A circuit. Safer still is using it to temporarily augment the furnace, not replace it.

Although the fireplace in my coach is on a dedicated circuit it is still on a 15A circuit. By this criteria, does it mean that the 15A circuit is inadequate for the fireplace?

 

[desert rat]

Thank you Heartlanders, for the great information and suggestions. I have learned enough to alter what I do, especially with space heaters. One in the living room on low sends enough warm air into the bedroom for this winter in south Texas (I know, don't laugh!).

Wind? Last April, Clovis, New Mexico, I was concerned, but the Sundance stood strong in the 60-80 mph wind.

 

[Ray LeTourneau]

We just had an incident last weekend with our wiring. The wiring in the junction box under the dining area slide burned completely out. This junction box is for the one outlet in the slide. The only thing on this outlet was a ceramic heater so the circuit should not have been overloaded. What is concerning to me is that the circuit breaker did not trip and the remaining outlets on this circuit remained hot. We are fortunate that the burning was contained within the junction box which is outside the camper so there was no smoke, fire or fumes inside; however, we are now leary of the other circuits within the coach, especially the fireplace circuit. Why didn't the circuit breaker trip and why did the wires burn????

The possibility of a loose wire nut may cause the wires at the connection to get hotter than normal. Also a loose plug in an outlet will cause heat at the plug.

 

[porthole]

Gang:
I have seen too many roasted crimp connectors in my career. I prefer to add a soldered joint to any crimp connector I encounter in a power (not logic) circuit. Solder enters the metal crystalline matrix on each of the metal surfaces it is applied to making a superior electrical connection, and makes an airtight seal on top of the metal-to-metal crimp connection, which renders it corrosion proof.

And I have seen even more poor solder joints.

There are reasons why stranded wire and crimp connectors are used/required on boats.

Vibration issues is one and the lack of ability on many to perform a correct solder joint is another.

I can solder, learned from a master (the old man), but I frequently use crimps and heat shrink tubing.

Solder only joints are subject to fracturing with little stress. We're talking moving objects here, trailers (and boats motorcycles etc)

On my motorcycle's Deutsche connectors I almost always solder the pins and sockets as I don't have the $150 crimper.

I certainly would not rely on a solder only joint for a 20 amp AC circuit.

 

[htneighbors]

OK, I'll give you my take here.

According to the NEC, although Type NM-B cable (Romex) contains 90°C conductors, Article 334.80 limits its ampacity to the 60°C level. This being said, according to the 60°C column of Table 310.16, the ampacity of #14 is 20A. However, according to Article 240.4(D)(3), the overcurrent protection (breaker) cannot exceed 15A for #14 wire. ​

A continuous load is a load where the maximum current is expected to continue for 3 hours or more. ​

Article 210.19(a)(1) states the circuit conductor size of a continuous load branch circuit must have an allowable ampacity not less than the noncontinuous load plus 125% of the continuous load. ​

Article 210.20(A) states the same thing about the the overcurrent device (breaker). ​

Therefore, the max breaker for #14 wire is 15A. Although the conductor itself is rated for a continuous load of 16A, installation rules say otherwise. ​

In a nutshell: Most of the RV factory installed circuits for the convenience receptacles have more than one receptacle and are #14 wire on 15A breakers. The safest way to run a 1500W heater continuously is, like many have done, to install a single receptacle, on a separate circuit, for your heater. When you do so, go ahead and run #12 wire and put it on a 20A breaker! ​