outlet keeps blowing

[DonTom]

There will be a long time trip which is usually around 80% of the marked rating.

Did it say how long there somewhere that I missed?

How long does it take a new good 20 amp cb to trip open at 19.5 amps continuous?

-Don- Giddings, TX

 

[DonTom]

Most 50A RVs will have two outlet circuits.

I assumed all the 50amp RVs had the two 50 amp lines. I know this one does. L1 to the kitchen. L2 to the same outlets that are activated with the stock inverter. That makes it easy for me to tell which is which. I have often needed to know. For an example, I cannot charge my electric motorcycle on the same line when I use the MW oven.

Some RV Park pedestals don't have an extra outlet. The one in DeRidder only had a 14-50R, so then I have to charge the bike through the RV.

-Don- Giddings, TX

 

[Lou Schneider]

A 1500 watt heater at 120V will draw 12.5A. At 110V it would draw 13.6A.

No, the heater only draws 1500 watts at full voltage. Since the resistance stays constant both current and the amount of heat produced will be less at lower voltages. A 1500 watt, 120 volt heater draws 12.5 amps at 110 volts and produces 1375 watts of heat.

 

[Ex-Calif]

I run an 1800W electric heater all the time. Saves on propane.

However, I am currently plugged into a 20 amp house circuit and it kept blowing the outlet. I figured out that it is also on the "utility" room plug which apparently also feed the microwave plug through the wall. I correlated the tripping with heating up coffee - LOL

I found another 20 amp plug and it hasn't blown this week.

I also realized the 30amp plug was on the ground and had gotten pretty wet. I opened it up and dried it out as well.

 

[HappyWanderer]

Has 110VAC been used anywhere in the USA in the last 50 years? Even under that 14 amp load?

-Don- Giddings, TX

I was at a campground last year where the voltage was 92 to 104. Had to use the 20 amp receptacle in the pedestal, because that leg was 104 to 108 volts which my EMS would tolerate.

 

[DonTom]

I was at a campground last year where the voltage was 92 to 104.

I wonder what was wrong there at the camp. I doubt the neighborhood was that low.

-Don- Giddings, TX

 

[DonTom]

No, the heater only draws 1500 watts at full voltage. Since the resistance stays constant both current and the amount of heat produced will be less at lower voltages. A 1500 watt, 120 volt heater draws 12.5 amps at 110 volts and produces 1375 watts of heat.

But Kirt is correct if it is really at 1500 watts even at the lower voltage. And such is possible, as that is how the onboard charging is on my electric motorcycle, which I have with me now, is designed. On it, as the voltage is increased the current goes DOWN by design. It's a 1400 watt charger at any voltage from 90 to 250 VAC. They should be able to design a heater to do the same. On this motorcycle the 1400 watt charger would melt if they let the current increase when 250 VAC was used.

-Don- Giddings, TX

 

[Mark_K5LXP]

DonTom you're right, with an active/SMPS device. But with a resistive heater it's not going to self regulate for constant power. Maybe not perfectly linearly like a resistor, as nichrome or whatever changes resistance with temperature but overall when voltage goes down the power draw will go down with it.

A looooong time ago I lived in the boonies in Newfoundland (is there anything but the boonies in NFLD?) and the power was so unstable (...how unstable was it?...) that the stereo turntable I had (remember, this was a looong time ago) would constantly wander in speed as evidenced by the strobe on the edge of the platter. The shop I worked at had a input voltage meter on the equipment and it would go anywhere from about 105 up to 125 over the course of a shift and when it dipped below 105 the facility generator would fire off and run until the utility power became more stable.

Mark B.
Albuquerque, NM

 

[Gary RV_Wizard]

"Does a 20 amp breaker trip at exactly 20 amps? Actually, a 20 amp breaker must trip at a sustained current of 27 amperes (135 percent) at less than one hour, and at 40 amperes (200 percent of wire rating) in less than 120 seconds—"

Note that it says "Must trip". Doesn't say it cannot trip at a lesser amperage. The ratings are about assured safety, not convenience or performance. Nothing guarantees that you can continuously pull 15A from a 15A outlet or branch circuit. And as Mark says, poor connections and over-stuffed boxes can drive the breaker heat up, sometimes pushing the rating limits.

But I'll withdraw my opinion because it may not be relevant here and I don't want to go further off-topic.

 

[csarm]

You have an actual fuse in your outside power box? As opposed to a circuit breaker? What size (amperage) fuse and is it the one for the outlet the RV's shore cord is plugged to? An description of the power set-up on your campsite and your RV's power needs (30A, 50A, etc) would be helpful.

Just to be clear, you are saying the GFCI in the outlet does NOT trip. What are the circumstances that cause the outside fuse to blow, e.g. some electrical appliance plugged in or ???

I do have an actual fuse. I have a power box that has (2) 30amp actual fuses (for two rv hookups) outside of my trailer. My rv is plugged into a connection to one of the fuses. I have a circuit breaker box inside of my trailer. So my setup is: 30 amp fuse outside plugged into rv. Rv has breaker box inside with 6 breakers. One of the breakers is labeled GFCI (labeled by someone else in pen writing, so could be wrong). When I plug my 1500 Watt heater into a 12/3 10ft extension cord into one of the 3 GFCI outlets, and run it on medium (pulling 6-7 amps- I checked it with a multimeter clamp), after a anywhere from 5 mins - 2 hours, the heater will trip the outlet and the power on the entire trailer goes out, and I have to replace the 30 amp fuse outside in the fuse box. I have tried this on two different GFCI outlets with two different heaters, and two different extension cords, which indicates to me that it's something in the circuit. What's weird is that this wasn't a problem until I accidentally overloaded the circuit with additional appliances a few days ago. Then, now only running just the heater and internet on that circuit (which I've been doing for a month or two with no problem), it can't handle. Thoughts?

 

[DonTom]

Note that it says "Must trip". Doesn't say it cannot trip at a lesser amperage.

Good point. I guess I will have to get a 20-amp breaker and put a load of 19.5 amps on it and see how long it takes to pop. But if I don't live long enough to see it happen, can some young guy here take over the experiment? .

Two things are inevitable, death and popped circuit breakers. But which comes first when a 20 amp CB has a 19.5 amp load?.

-Don- Ft. Stockton, TX

 

[Lou Schneider]

When I plug my 1500 Watt heater into a 12/3 10ft extension cord into one of the 3 GFCI outlets, and run it on medium (pulling 6-7 amps- I checked it with a multimeter clamp), after a anywhere from 5 mins - 2 hours, the heater will trip the outlet and the power on the entire trailer goes out, and I have to replace the 30 amp fuse outside in the fuse box.

The only thing that will blow a 30 fuse is a direct short. Fuses pop faster than circuit breakers open, so you almost certainly have a direct short inside the heater that's blowing the fuse. Maybe it happens when the thermostat or overtemperature switch opens.

One other possibility comes to mind - do you have a MOV based surge suppressor somewhere in the trailer? These conduct when they see a voltage spike, creating a dead short long enough for an upstream fuse or circuit breaker to blow and disconnect the power. Maybe the heater is operating normally but creates a voltage spike that trips the MOV when it's thermostat opens.

 

[Ex-Calif]

The only thing that will blow a 30 fuse is a direct short. Fuses pop faster than circuit breakers open, so you almost certainly have a direct short inside the heater that's blowing the fuse. Maybe it happens when the thermostat or overtemperature switch opens.

If the fuse on the house is blowing I would plug the heater directly into the shore power to test this before buying a new heater.

 

[Mark_K5LXP]

Take that clamp on ammeter and watch the current at the pedestal. Since there's more than one 20A circuit in the camper it's entirely plausible no one circuit is overloaded but in aggregate it's exceeding the capacity of the pedestal. Example, resistive heater is pulling 15A, fridge and some other stuff is running, then the electric water heater pops on and presto, overload.

Mark B.
Albuquerque, NM

 

[Gary RV_Wizard]

I guess I will have to get a 20-amp breaker and put a load of 19.5 amps on it and see how long it takes to pop. But if I don't live long enough to see it happen, can some young guy here take over the experiment? .

LOL, DonTom. If you buy a top-quality breaker that might happen. But try it with one of those el cheapo "contractor grade" items and you probably won't have long to wait.

Kirk already explained the 3 stages or criteria for breaker trips but you poo-poohed that too. And described the committee that produces the National Electrical Code as "paranoid". They may be, but it's because they have learned over the years that bizarre things go wrong and sometimes result in danger to human life.

 

[Lou Schneider]

LOL, DonTom. If you buy a top-quality breaker that might happen. But try it with one of those el cheapo "contractor grade" items and you probably won't have long to wait.

And "contractor grade" is often an upgrade to what's put in a typical RV.

 

[DonTom]

The only thing that will blow a 30 fuse is a direct short.

You mean a 60 amp load won't?

-Don- Fabens, TX

 

[DonTom]

If you buy a top-quality breaker that might happen.

That's what I always meant. Not the cheap Chinese junk
that can trip if they are simply looked at.

-Don- Fabens, TX

 

[John From Detroit]

No, the heater only draws 1500 watts at full voltage. Since the resistance stays constant both current and the amount of heat produced will be less at lower voltages. A 1500 watt, 120 volt heater draws 12.5 amps at 110 volts and produces 1375 watts of heat.

Resistance is not constant. it goes down as the temperature goes down. However. the difference in heat between 120 and 110 volts is not great enough to make a significant change in resistance.. but measure one cold some time. You might be surprised.

 

[CharlesinGA]

I do have an actual fuse. I have a power box that has (2) 30amp actual fuses (for two rv hookups) outside of my trailer. My rv is plugged into a connection to one of the fuses. I have a circuit breaker box inside of my trailer. So my setup is: 30 amp fuse outside plugged into rv. Rv has breaker box inside with 6 breakers. One of the breakers is labeled GFCI (labeled by someone else in pen writing, so could be wrong). When I plug my 1500 Watt heater into a 12/3 10ft extension cord into one of the 3 GFCI outlets, and run it on medium (pulling 6-7 amps- I checked it with a multimeter clamp), after a anywhere from 5 mins - 2 hours, the heater will trip the outlet and the power on the entire trailer goes out, and I have to replace the 30 amp fuse outside in the fuse box. I have tried this on two different GFCI outlets with two different heaters, and two different extension cords, which indicates to me that it's something in the circuit. What's weird is that this wasn't a problem until I accidentally overloaded the circuit with additional appliances a few days ago. Then, now only running just the heater and internet on that circuit (which I've been doing for a month or two with no problem), it can't handle. Thoughts?

It almost sounds like you have a poor connection somewhere, creating extra resistance and overloading the circuit, but I would think by now, you would have had a fire if that were the case. From your description, the circuit breaker itself is a normal breaker but the circuit feeds the GFCI somewhere else? If so, am I to understand that all of the outlets supplied by the GFCI go dead if you do a test on the GFCI receptacle, or do some stay live and some go dead.

What I am getting at is I have two "general purpose" circuits. One feeds the dinette, the kitchen counter the bath room (GFCI) receptacle, (which are all on the LH side of the trailer) and then the circuit crosses to the right side to supply the outside receptacle. The kitchen and the outside are fed thru the GFCI and the other one is not, but all are on one breaker.

The Breaker and the GFCI are the one place that have actual screws you can tighten up (with the power disconnected completely of course). The others have nothing to tighten.

If you have not, open the breaker panel, and remove the cover that covers the breakers and other wiring (again, power completely removed/unplugged) and check the tightness of all screws on the neutral and ground bars, along with the breakers.

Another thing to do is consider borrowing another space heater for a day or two and try it.

Charles