200 foot extension cord

[RT-NY]

A 15 amp 200 foot 12awg extension cord rated for 1875 watts should easily be able to handle a 900 watt electric heater plus a 160 watt fridge plus another 60 watts for lights, computer, etc. Still, I wonder how safe such a long extension cord is, especially with a heater. Any thoughts on safety?

[booster]

Even at 10 amps you are going to have over 5% voltage drop, which can be a problem for some devices. They will also try to pull more amps in many cases making things worse yet.


I know you can find cords that long on the internet, I have even seen 16ga cords rated at 200' and over 1600 watts. All of them are scary to me and I wouldn't use them. They are all imported that I found and imported wiring is getting kind of famous for not meeting the full conducting area that a given wire gauge is supposed to have. Read reviews on single conductor wire on Amazon for instance and you will likely find lots of complaints about not making gauge spec.

I use 100' 12ga cords at home for some of the yard tools, sometimes, like leaf blowers, small electric chainsaw, etc and have found anything beyond 10 amps just doesn't work well even at 100'.

With a 10ga cord at 10 amps, which is close to your example, you probably would be getting close to having 5% drop which is what I think the NEC says should be the max. Remember you also have to count for all the wiring to outlet and in the van once you get there as all those have drop also. A 200' 10ga cord is going to be quite big and heavy and a pain to roll up without using a cord reel.

[phantomjock]

Serendipity?
Just noted this morning @ Harbor Freight 100' extension cord 10/3 for $120. That is with the coupon. But the sale ends today, then back to $140.

Cheers - Jim

[RT-NY]

Originally Posted by booster

Remember you also have to count for all the wiring to outlet and in the van once you get there as all those have drop also.

I see there are online calculators for voltage drop. So is this just a matter of adding up the voltage drop of the various runs and keeping that under 5%? That is: voltage drop from breaker box to receptacle + voltage drop of extension cord + voltage drop of van wiring?

[booster]

Originally Posted by RT-NY

I see there are online calculators for voltage drop. So is this just a matter of adding up the voltage drop of the various runs and keeping that under 5%? That is: voltage drop from breaker box to receptacle + voltage drop of extension cord + voltage drop of van wiring?

Generally, yes, that is how it is works in the theoretical sense. In the real world it is very hard to do because you rarely know the actual length and size of the wiring to outlets or the voltage that the line started at in the first place. You could be starting with anywhere from probably 110v to 125v depending on the area you are in. Our home voltage is at 117v normally, for instance, but other homes in other areas are different.


I just looked and it appears a Progressive Power Protector disconnects at 104v, so that would be what they consider the necessary level for devices to work properly. IMO have a protector is a good idea or at least a low and high voltage cutoff device.


On a long cord like 200' you are probably going to drop below that level whenever some of the items are starting up as they will pull higher than there rated input amps. Air conditioners are notorious for that and even battery chargers have big surges sometimes.


I think you see the voltage drop spec in the cords being used because they understand the lack of total information of the rest of the system and 5% is a good place to estimate what the cord's contribution to total drop is.


Campgrounds, if that is where you are using it, are pretty famous for having poor power with low voltage being a big deal many places. We have seen under 110v quite a few times and tripped the power protector when the AC or Microwave would start up.


In Canada and some of the far northern areas of the U.S. you run into campgrounds with centralized power poles the can require very long extension cords. They usually recommend using 10ga cords, but few of us carry 100' of 10ga cord with them, I think. We carry a 50' and two 25' 12ga cords and try to use the shortest one possible if we have to extend the power cord. We have rarely needed more than the 50' cord and still were very careful about our power use and particularly the AC.

[peteco]

Originally Posted by booster

I just looked and it appears a Progressive Power Protector disconnects at 104v, so that would be what they consider the necessary level for devices to work properly. IMO have a protector is a good idea or at least a low and high voltage cutoff device.

My Progressive Industries EMS-HW30C has the low cutoff at 104v. After 8 years of use I just had my first cutoff at a campsite when I tried to run my microwave. It happened again at my house when I tried the microwave and the long (but thin gage) extension cord created a large enough voltage drop. I put in a heavier gage extension cord and had no problem.

This experience highlighted the value of having enough onboard power (ideally batteries, or generator) to run heavy draw appliances (microwave, AC).

[booster]

Originally Posted by peteco

This experience highlighted the value of having enough onboard power (ideally batteries, or generator) to run heavy draw appliances (microwave, AC).

We are also the route to not using shore power, but not to the extreme of running AC on batteries because of the need to replace too much energy to the batteries. Never, ever, thought that I would ever be able to trust running on batteries for thinks like the microwave or a hair dryer more than shore power.


The inverters that do the load sharing routine are pretty slick as they will supplement shore power with battery generated AC if the voltage sags too much. Great for filling in the starting surges with AC and other high surge items, I would think. I don't think our Magnum MS 2000 does has that option.

[RT-NY]

Originally Posted by peteco

My Progressive Industries EMS-HW30C has the low cutoff at 104v.

Does anyway know what would be the least expensive portable Progressive Industries (or similar) protector that has a low voltage cutoff?

[peteco]

Originally Posted by RT-NY

Does anyway know what would be the least expensive portable Progressive Industries (or similar) protector that has a low voltage cutoff?

Looks like the Progressive Ind portable EMS-PT30X is more expensive than the built-in EMS-HW30C. I like the built-in unit as I don't have to worry about rain damage or theft. Plus I have a readout of the main shore power information inside the RV. I installed mine, but would pay to have it installed if I was not able to do it myself.

[habsfan59]

You can use an online calculator...!

https://www.calculator.net/voltage-d...s=27&x=93&y=26

Cheers,

[avanti]

I was browsing through the many graphs that the Victron power system can produce, and I came across one that made me think of this thread. It shows a real-life example of the voltage-drop discussed above.

The van was connected to 15A shore power via one of these:

Extension cord.jpg

https://www.amazon.com/gp/product/B00NY3ZQAY

It was a chilly evening and the van's electric heater was set cycle off and on to keep things above freezing. The graph shows the relationship between the cycling current load from the heater and the AC voltage at the van side of the extension cord:

voltage drop.jpg

Nothing like a real-life example to bring the equations to life. Interestingly, the voltage drop appears to be significantly greater than what the calculators say it should be. The cord is supposedly all-copper, not CCA. But, who knows?

[booster]

Originally Posted by avanti

I was browsing through the many graphs that the Victron power system can produce, and I came across one that made me think of this thread. It shows a real-life example of the voltage-drop discussed above.

The van was connected to 15A shore power via one of these:

Attachment 14367

https://www.amazon.com/gp/product/B00NY3ZQAY

It was a chilly evening and the van's electric heater was set cycle off and on to keep things above freezing. The graph shows the relationship between the cycling current load from the heater and the AC voltage at the van side of the extension cord:

Attachment 14368

Nothing like a real-life example to bring the equations to life. Interestingly, the voltage drop appears to be significantly greater than what the calculators say it should be. The cord is supposedly all-copper, not CCA. But, who knows?

Nice graph to have and sure does show a big drop.


Of course some of the drop would be within the house, also, on the circuit that feeds the 15amp outlet. By the time you figure in maybe another 30-50 feet of wire and a bunch of outlets by the time it gets to the Victron, I could see that much drop happening.


Of course the actual copper, if it really is copper, wire total crosssection could be undersized also. I have found several cords that were on the light side of that spec in the imported cords.


Is your AC line always that high at nearly 125v? That is getting to the high end of the scale. Ours runs pretty steady 117v, so we would have less drop available before running into trouble.

[avanti]

Originally Posted by booster

Of course some of the drop would be within the house, also, on the circuit that feeds the 15amp outlet.
...
Is your AC line always that high at nearly 125v?

I lied: The van is plugged into a dedicated 20A outlet that I installed a long time ago and forgot about.

Anyway, you are right about the in-house wire run. I just measured the voltage at three places:
1) At an outlet right next to the house panel.
2) At the 20A outlet that the extension cord is plugged into.
3) As reported by the Victron in the van.

This is what I saw:

amps -- panel / plug / van
1.1A -- 123V / 122V / 122V
12.2A -- 123V / 119V / 114V

Science at work.

I've never paid much attention to our home voltage, but judging from the graph, it looks like it bounces around quite a bit. I imagine one's position in the grid topology matters.

[booster]

Originally Posted by avanti

I lied: The van is plugged into a dedicated 20A outlet that I installed a long time ago and forgot about.

Anyway, you are right about the in-house wire run. I just measured the voltage at three places:
1) At an outlet right next to the house panel.
2) At the 20A outlet that the extension cord is plugged into.
3) As reported by the Victron in the van.

This is what I saw:

amps -- panel / plug / van
1.1A -- 123V / 122V / 122V
12.2A -- 123V / 119V / 114V

Science at work.

I've never paid much attention to our home voltage, but judging from the graph, it looks like it bounces around quite a bit. I imagine one's position in the grid topology matters.

Thanks for measuring that, there is no substitute for accurate data in cases like this.



I kind of figured it would be something like that as there is a lot of wiring in a house and it never seems to run in the shortest path to anywhere.


Easy to see that if you are at the furthest away from the transformer campsite in a busy campground how you could have very low voltage.

[RT-NY]

Originally Posted by avanti

It was a chilly evening and the van's electric heater was set cycle off and on to keep things above freezing. The graph shows the relationship between the cycling current load from the heater and the AC voltage at the van side of the extension cord:

Nothing like a real-life example to bring the equations to life. Interestingly, the voltage drop appears to be significantly greater than what the calculators say it should be. The cord is supposedly all-copper, not CCA. But, who knows?

Thats for that -- it is very helpful. I understand that voltage drop might cause problems with some electronics. What effect would it have on an electric heater? Would the heater just not put out as much heat, or would it keep trying to draw more amps until it burns up the extension cord?

[booster]

Originally Posted by RT-NY

Thats for that -- it is very helpful. I understand that voltage drop might cause problems with some electronics. What effect would it have on an electric heater? Would the heater just not put out as much heat, or would it keep trying to draw more amps until it burns up the extension cord?

I am sure Avanti will be able to fill in the blanks on that if he has checked the heater amp draw with and without the cord, and will also be able to answer this question in theory.



An electric resistance heater, which is probably what Avanti is using, does not draw more current. Formula is I=E/R if interested in that. This means that a heater is immune from the runaway current problem. You can still, however, have the control unit of the heater quit working if it is digital. If it is mechanical it won't be affected.


Motors are primarily the ones that get into amperage increases at low voltage and appliances like microwaves seem to do it also and even the charging bricks for things like laptops, until they hit shutoff voltage.

[avanti]

The heater in question is a Rixen's 1500 watt resistive coil that is located in the glycol reservoir tank. It, and all other AC loads, are run through the Victron Multiplus inverter/charger. (I did this because it is occasionally useful to heat the glycol loop from battery power via the inverter). The Multiplus has a setting that caps the current that it will attempt to draw from the shore power connection. If the AC loads exceed this value, the inverter will make up the difference from the battery. This same current limit setting is used to prevent overloading my DC-AC-DC setup for charging from the Transit's electrical system. (I usually have it set at 13A @120VAC, although this a bit conservative for the Transit's very-capable dual alternators. It is easy to change to 30A when using campground shore power.)

[JohnnyFry]

The issue here is not burning up the cord, as it is rated to carry 15 amps, tissue is voltage drop. This is a problem because it affects the operation of appliances. Your air conditioner and microwave, because they are heavy loads and tend to be sensitive to low voltage, are especially prone to damage. Nobody cares if the light bulbs are dimmer, but if your A/C dies because of the effects of low voltage, you are not going to be happy. My advice is to have a voltmeter monitoring the voltage in your R/V so you can turn things off if it drops too low (under 105) I carry a 10/3 50 foot extension that I consider the most I am willing to use, and even at that, I monitor the voltage at the panel in my rig.

[booster]

Originally Posted by JohnnyFry

The issue here is not burning up the cord, as it is rated to carry 15 amps, tissue is voltage drop. This is a problem because it affects the operation of appliances. Your air conditioner and microwave, because they are heavy loads and tend to be sensitive to low voltage, are especially prone to damage. Nobody cares if the light bulbs are dimmer, but if your A/C dies because of the effects of low voltage, you are not going to be happy. My advice is to have a voltmeter monitoring the voltage in your R/V so you can turn things off if it drops too low (under 105) I carry a 10/3 50 foot extension that I consider the most I am willing to use, and even at that, I monitor the voltage at the panel in my rig.

Even better is to put in a power protector that includes high and low voltage cutouts.

[JohnnyFry]

Absolutely…although there have been situations (rare) where I have overruled the Progressive device, something I would not usually advocate.