Extension Cord

[kearlms]

We have found ourselves in a spot where we are going to have to live in our camper for a bit and need to purchase an extension cord that will reach the closest power. I am looking at a heavy duty 100 ft 12 gauge extension cord. I will only be plugging into a 15 amp plug for the time and it is about 100 ft from the trailer. We wont be using the A/C and will only be using lights, TV, and heater when needed. So, my question is will this be good enough for us?

[Acdii]

Scuse me while I go pop some popcorn



OK, I'm back, fun reading for sure.

Here is what I have done. I have a 30 amp service and had a 15 amp converter plug plugged into 12 ga extension cords, a 25' and a 50'. Worked good the first year, could run everything including AC off it. Second year my voltage line conditioner kept tripping. I discovered the conductors in the cord had corroded, causing a voltage drop.

I went and bought a 100' roll of outdoor heavy duty 10/3 cable and two 30 Amp fittings, along with a 30 Amp outlet, breaker and wiring. Since I run the feed from my barn, it was easy to run the outlet to a place near the door. Now I can run the entire trailer off the 30 Amp service as if I were in an RV park.

If the OP can't run the outlet, at the very least make a 100' outdoor 30 amp cord. Use the adapter at the end of it. Most important though, KEEP the connection OFF the ground!

[opnspaces]

kearlms wrote:
Seems like a bunch of confusion about heating and AC. We will only is the furnace not a 1500 watt heater. AC is not even a consideration as out highs are fairly hitting mit to upper 60's. We also have a gen set if we need any big loads we will hook that up and get the 30 ampswe need. Hope this clears some things up.

Furnace only
refrigerator on propane
propane range/oven
water heater on propane
occasional microwave

You'll be fine on the 12 gauge cord. Except the Microwave might struggle. If it does just run the generator for the microwave. You should exercise the generator from time to time anyway.

[Boomerweps]

drsteve wrote:

myredracer wrote:
Sorry, but you clearly don't understand voltage drop in a branch circuit.

Yup... The outlet you plug the extension cord in to probably is not putting out 120V in the first place. To get a true idea of the voltage at the end of the cord, you need to know the real world voltage at the outlet. Not just the theoretical 120V number from the power company.

It's like using the brochure dry weight to figure out what you can tow.

The voltage will not drop until placed under load. When testing last fall on a hot day in the afternoon, I read 122 VAC on my EMS in my TT with just the converter using power with the battery charged. This was through 110' of 12 AWG from breaker box to the TT. Once I turned on the AirCon voltage read 107.7, added on the refrigerator then voltage read 104.5. At that point I was pulling 15.8 amps per the EMS.
I don't trust guesses or estimates any more than I have to. I prefer measurements. It's that submarine training thing 😉

[drsteve]

myredracer wrote:
Sorry, but you clearly don't understand voltage drop in a branch circuit.

Yup... The outlet you plug the extension cord in to probably is not putting out 120V in the first place. To get a true idea of the voltage at the end of the cord, you need to know the real world voltage at the outlet. Not just the theoretical 120V number from the power company.

It's like using the brochure dry weight to figure out what you can tow.

[Boomerweps]

As an RV owner, sooner or later you will learn about your RV electrical systems, usage and means of supply, due to the RV's limited electrical system.
Remember the old television show, "Green Acres"? How the husband had to number code all the plugs so his wife wouldn't overload the system again, as she did frequently. Everything was plugged into extension cords. Think of your RV electrical system like that, only with a more limited power supply.
Check with an electrician, you may be able to bump that supply circuit from a 15 to a 20 amp circuit breaker. A long as the feed line is 12 AWG, its normally OK by NEC code.
More data, better decisions. I again recommend the Kil-A-Watt meter. Using a regular 15 amp plug extension cord with the 15-30 amp cord adapter near the RV, you can monitor power use of your various gear and check for excessive voltage loss.
For all, there is a plug in digital voltmeter on Amazon for about $10. I put one in the power strip beside my door so I can see the voltage when I walk in or out. No outlets near there ;(. My EMS is under the dinette bench by the TT power inlet and I was too cheap to get the remote read version.

[myredracer]

Sorry, but you clearly don't understand voltage drop in a branch circuit. But what do I know, I'm just a lowly EE. There's really no point in discussing it further...

SoundGuy wrote:

SoundGuy wrote:
The OP's original question was whether 100' of 12 gauge drawing from a 15 amp circuit would be suitable for his intended use and the answer is YES. Even assuming a maximum draw of 15 amps voltage drop over that 100' of 12 gauge would only be 4.76 volts.

myredracer wrote:
What you are ignoring is the overall length of what the circuit could be. Is it 200', 250' or maybe 300'

Wrong again - the OP specifically said this cable run would be 100', drawing from a 15 amp source. This voltage drop calculator specifies "distance" as the one way distance from source to load. Obviously we have no way of calculating any further loss within the rig itself, nor does the OP - but the point remains that loss over 100' of 12 gauge even when drawing a full 15 amps is still well within acceptable limits.

[SoundGuy]

Here in Ontario the runs from where my camper is located on the campsite to the power post is more often than not a long way so I always carry a minimum of 100' of cable. However, dragging that much 10 gauge around when we rarely use A/C gets old very quickly so I'm made up a couple of 12 gauge extensions which are much lighter and easier to deal with. One is 25', used those few times the campsite power post is located quite close to the camper, and a 75' when it's not. Each cable is terminated with Leviton Wetguard 15 amp plugs & receptacles and when used together allow me to even reach a power post that's 100' away. I can therefore plug directly into campsite 15 amp service (or 20 amp when we happen to be in the US) or I can also dogbone the post end of the cable so I can plug into 30 amp service. Typically we draw only a few amps at any given time so voltage drop is irrelevant but those times we may use an electric heater voltage drop is still within accepted limits and the heater itself, as a resistance load, doesn't care whether incoming source voltage under load may be 115 vac or 105 vac, it works just fine. :B

[SoundGuy]

SoundGuy wrote:
The OP's original question was whether 100' of 12 gauge drawing from a 15 amp circuit would be suitable for his intended use and the answer is YES. Even assuming a maximum draw of 15 amps voltage drop over that 100' of 12 gauge would only be 4.76 volts.

myredracer wrote:
What you are ignoring is the overall length of what the circuit could be. Is it 200', 250' or maybe 300'

Wrong again - the OP specifically said this cable run would be 100', drawing from a 15 amp source. This voltage drop calculator specifies "distance" as the one way distance from source to load. Obviously we have no way of calculating any further loss within the rig itself, nor does the OP - but the point remains that loss over 100' of 12 gauge even when drawing a full 15 amps is still well within acceptable limits.

[GrandpaKip]

myredracer wrote:

SoundGuy wrote:


I'd go remeasure each of the 1/2 dozen electric heaters I own but guess what - I don't have to "back up" anything and frankly don't care whether you believe it, or not. 😛 FACT is, only one of my heaters that are labeled as "1500 watt" draws anywhere near that much, ALL the rest pull much less.

You muddied the waters by bringing up that heaters put out a fair bit less than their rating. I recommend reading the UL standard for portable electric space heaters which covers construction details, testing and labeling. Do you know what the OP's heater might put out?

The OP's original question was whether 100' of 12 gauge drawing from a 15 amp circuit would be suitable for his intended use and the answer is YES. Even assuming a maximum draw of 15 amps voltage drop over that 100' of 12 gauge would only be 4.76 volts.

What you are ignoring is the overall length of what the circuit could be. Is it 200', 250' or maybe 300' and how much is #14 ga? It's also important to take into account the starting voltage at the source. Not knowing either, nobody can assure that #12 is adequate for an extension cord - you cannot look at 100' of extension cord in isolation and assume that the starting voltage is 120 volts.

For example: Say the wiring in the house was 100' of #14 panel to plug (or whatever it is being plugged into), the extension cord is 100' of #12 and the shore power cord is 25' of #10, at a starting voltage at the source of 120 volts at a draw of 15 amps, the voltage would be down to 106.9 volts in the RV for a drop of 11%. Even then, that ignores what the wiring from the house's panel is to the street, how long and what gauge, which could (and sometimes does) affect voltage drop. I don't think the OP has provided adequate info. to make a definitive determination. If someone want to try and save $50 or so to take a gamble, that's up to them.

Hey guys, he’s not gonna use an electric heater.

[myredracer]

SoundGuy wrote:


I'd go remeasure each of the 1/2 dozen electric heaters I own but guess what - I don't have to "back up" anything and frankly don't care whether you believe it, or not. 😛 FACT is, only one of my heaters that are labeled as "1500 watt" draws anywhere near that much, ALL the rest pull much less.

You muddied the waters by bringing up that heaters put out a fair bit less than their rating. I recommend reading the UL standard for portable electric space heaters which covers construction details, testing and labeling. Do you know what the OP's heater might put out?

The OP's original question was whether 100' of 12 gauge drawing from a 15 amp circuit would be suitable for his intended use and the answer is YES. Even assuming a maximum draw of 15 amps voltage drop over that 100' of 12 gauge would only be 4.76 volts.

What you are ignoring is the overall length of what the circuit could be. Is it 200', 250' or maybe 300' and how much is #14 ga? It's also important to take into account the starting voltage at the source. Not knowing either, nobody can assure that #12 is adequate for an extension cord - you cannot look at 100' of extension cord in isolation and assume that the starting voltage is 120 volts.

For example: Say the wiring in the house was 100' of #14 panel to plug (or whatever it is being plugged into), the extension cord is 100' of #12 and the shore power cord is 25' of #10, at a starting voltage at the source of 120 volts at a draw of 15 amps, the voltage would be down to 106.9 volts in the RV for a drop of 11%. Even then, that ignores what the wiring from the house's panel is to the street, how long and what gauge, which could (and sometimes does) affect voltage drop. I don't think the OP has provided adequate info. to make a definitive determination. If someone want to try and save $50 or so to take a gamble, that's up to them.

[pianotuna]

myredracer,

One has to factor the voltage in--most folks just don't bother, so they get lower or very occasionally higher wattages.

My 1500 watt oil filled is pretty much "spot on". My 1/2 size oil filled is 462 watts, instead of the rated 500.

[SoundGuy]

pianotuna wrote:
So that 1500 watt heater puts out only 1,140 watts.

SoundGuy wrote:
Rarely does a so-called "1500 watt" electric heater actually draw 1500 watts, most often much less.

myredracer wrote:
I'd like to see a link from credible sources that can back that up.

I'd go remeasure each of the 1/2 dozen electric heaters I own but guess what - I don't have to "back up" anything and frankly don't care whether you believe it, or not. 😛 FACT is, only one of my heaters that are labeled as "1500 watt" draws anywhere near that much, ALL the rest pull much less.

The OP's original question was whether 100' of 12 gauge drawing from a 15 amp circuit would be suitable for his intended use and the answer is YES. Even assuming a maximum draw of 15 amps voltage drop over that 100' of 12 gauge would only be 4.76 volts. Heck, even if the unloaded source voltage was as low as 110 vac voltage drop over that length of 12 gauge, pulling 15 amps, would still only be a loss of 4.33% and well within a preferred maximum loss of 5%. Choosing 100' of 12 gauge is a no-brainer for the OP's intended purpose. It's also a much less costly solution than 100' of 10 gauge.

[kearlms]

Our TT isn't that big. It is a 23' with no slide outs. Just a box. We camp in cooler weather all the time and the furnace does great to keep the temps up and comfortable in the TT. So we won't be using a supplemental heat source.

[myredracer]

First, it looks like the TT is in the 28-30' range. If it is indeed a 1500 heater you want to run, it won't be enough in colder temps say around 40F and less. If you set the heater up in the living area, it'll be icy cold in the bedroom area and you may want an electric blanket or heavy quilt(s). We have 2KW of recessed heaters in a 29' TT and when it gets down to 40F, it starts to feel uncomfortable and at the least need to use heavy socks and blanket on legs. The heaters also run continuous in colder temps. But we have never had to use the furnace. We are never out more than a couple of days in cold weather so condensation not a big issue. We have a roof fan that runs continuous.

Recommendation:
1. Get a #10 ext. cord. What if you bought #12 and found it's not enough? Money wasted. Spend the extra $50 +/- and be done with it.
2. Get a cord that is UL rated otherwise the quality is unknown. I had the connector on two retail store extension cords melt in the driveway before I installed a 30 amp RV outlet where we park the TT. Ext. cords aren't required to be UL labeled so beware.
3. Voltage drop needs to consider the length of shore power cord, extension cord, receptacle you're plugged into to the upstream panel, and length from the panel to the main source panel. Even the length of poco wiring can be a factor. I guarantee voltage drop will be more than expected. I'd even measure it now at the recept. before buying a new cord. If it is low now, it'll only get worse.
4. Install a permanently mounted LED voltmeter inside to monitor voltage. If in an RV park, voltage can go up and down a lot over a 24 hour period.
5. If running a portable electric heater, it does have it's risks. Do not coil up it's cord or put it under a carpet. Install a dedicated receptacle from the RV's panel. Ensure that the safety clearances are maintained at all times. If it were me, I'd install a permanent fan-forced recessed heater. Portable 1500 watt heaters usually have just a #16 ga. cord. If you're on metered power, you could get a rather high electric bill one day (BTDT).
6. Consider using the furnace for heat.

In cold weather, you need to exhaust out moisture laden air to prevent condensation and the damage it can cause. At the least, you need to crack open windows/vents. This will of course mean you need more heat inside and further tax a 1500 watt heater. Or get a dehumidifier. But then will draw more power. A heater also won't circulate air, exacerbating condensation in cabinets/closets.

pianotuna wrote:
Hi,

Don't buy a premade cord. Go to an electrical wholesaler and purchase 100 feet of #10-3. Get the type rated for cold weather and UV resistant.

Tuna-man is right on the money. Most wholesalers sell to the public. Savings can be a LOT over retail. You can get quality commercial grade plugs and connectors that way too.

pianotuna wrote:
120 x 120 = 14,400

105 x 105 = 11,025

11,025 / 14,400 =~76% or a loss of 24% of wattage.

So that 1500 watt heater puts out only 1,140 watts.

On the money again. A 1500 watt heater in a TT will end up running pretty much non-stop in cold weather (BTDT) at or near 120 volts. It won't be comfortably warm inside at or near 120 volts, and if significant voltage drop, your feet will feel like ice and you will need to bundle up otherwise.

SoundGuy wrote:

pianotuna wrote:
So that 1500 watt heater puts out only 1,140 watts.

Rarely does a so-called "1500 watt" electric heater actually draw 1500 watts, most often much less. I've got a 1/2 dozen electric heaters of various types and only one comes anywhere near to drawing 1500 watts, one when running on HI draws a little over 900 watts despite the fact it's labeled as a "1500 watt" heater.

I'd like to see a link from credible sources that can back that up. I tested several heaters a few years ago and got the rated output on the labels. If they don't, they aren't complying with the applicable UL/CSA standard. I'd like to see where in the UL standard it's okay not to provide the rated output. If the output is a lot less than the label, at 105 volts, they will put out waaay less than 1500 watts and be next to useless.