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Safest maximum length for extension chord from dryer?
- Thread starter GarZ.MYP
- Start date
ucmndd
Well-Known Member
There is no “safest maximum length”. The cord needs to have conductors sized for the amperage and expected voltage drop over the length of the run.
There are heavy duty 14-30 extension cords made for generators up to 100 feet or more. They will cost you a pretty penny. They also have twist-lock receptacles, which won’t do you any good.
There are heavy duty 14-30 extension cords made for generators up to 100 feet or more. They will cost you a pretty penny. They also have twist-lock receptacles, which won’t do you any good.
ucmndd
Well-Known Member
Here’s an example of what you should expect to spend for a good one.
AC WORKS 50 ft. STW 10/4 NEMA 14-30 4-Prong 30 Amp 125/250-Volt Heavy Duty Dryer Extension Cord-1430PR-050 - The Home Depot
AC WORKS 50 ft. STW 10/4 NEMA 14-30 4-Prong 30 Amp 125/250-Volt Heavy Duty Dryer Extension Cord-1430PR-050 - The Home Depot
ucmndd
Well-Known Member
I tend to agree, this is not really a permanent solution for charging an EV. A $200 extension cord is about half the way there to solving this problem the right way.
doghousePVD
My grandfather’s car
Agree about "doing it right", if you can find a competent electrician. (Many aren't).
Keep in mind an extension cord is meant for occasional use, so it's great if you are visiting your mother. It is not for leaving out in the rain as a semi-permanent daily charging system.
For traveling I got a 14-50 extension cord (heavier wire) then attach a 14-50 to 14-30 adapter. I carry a bag full of adapters, all which connect to 14-50. If you go this route, you must remember to set the charging rate in the car appropriately or else you will pop the breaker.
Keep in mind an extension cord is meant for occasional use, so it's great if you are visiting your mother. It is not for leaving out in the rain as a semi-permanent daily charging system.
For traveling I got a 14-50 extension cord (heavier wire) then attach a 14-50 to 14-30 adapter. I carry a bag full of adapters, all which connect to 14-50. If you go this route, you must remember to set the charging rate in the car appropriately or else you will pop the breaker.
Here's a suggestion for that. I've done this as have some other people with your setup. If you cut the neutral pin off of your Tesla 14-30 plug with a Dremmel or hacksaw, it can plug directly into your 14-50 extension, and the current will be set automatically without your having to remember to do it. That neutral pin is not connected to anything inside the adapter anyway.
kkillebrew
Banned
I was going to tell you to make one with instructions, but for 220 at 32 amps 40 feet is too long in my estimation. It will be huge and unwieldy and expensive. Is there no way you can do a run from your breaker box?
I did a 25ft dryer cord to charge at 24 amps and when combined with the mobile charger length it gets close to what you need but I limit the charge to 20 amps if unattended. Home Depot has precut lengths of rubberized AWG#12 made for what you want to do. It is in the RV section (not electrical) and right across the isle will be the appropriate Leviton outlet box for $7 and the Plug for about $20.
Lest people tell you that #12 is under rated, it's ampacity rating is quite adequate for this application at 25ft lengths. Go to #10AWG if you are not comfortable with #12.
I did a 25ft dryer cord to charge at 24 amps and when combined with the mobile charger length it gets close to what you need but I limit the charge to 20 amps if unattended. Home Depot has precut lengths of rubberized AWG#12 made for what you want to do. It is in the RV section (not electrical) and right across the isle will be the appropriate Leviton outlet box for $7 and the Plug for about $20.
Lest people tell you that #12 is under rated, it's ampacity rating is quite adequate for this application at 25ft lengths. Go to #10AWG if you are not comfortable with #12.
ucmndd
Well-Known Member
They’re asking to start at a 14-30 dryer plug (well actually they asked about a “15-30” but I’m just assuming that’s a mistake), so we’re talking about 24 amps here.
12 gauge is in no way adequate or appropriate for this. This is bundled cable being discussed, not separate wire in conduit, so it would generally fall in the 60 degrees C temperature rating, which is rated for only 20A circuits, providing 16A continuous current load. Even if you try to use the 75 degrees C rating level, that is only at 25A circuits for a 20A continuous load. That is still not appropriate for running on a 30A rated circuit with a 24A continuous load. 10 gauge wire would be the correct level for this kind of cord for a 14-30 outlet.
doghousePVD
My grandfather’s car
Sorta. The OP also has to saw off the neutral on the extension male, too, and label it so a dufus doesn't try to used it on a RV or another dryer. I understand your point.
However, if the user used his 14-50 plug (instead of the 14-30) on the Tesla charger, he would pop the breaker. So, if one isn't paying attention, stupid things can happen. Assuming the 14-30 circuit was installed properly, the worst that will happen is just a popped breaker. Not dangerous, but very annoying if one wakes up the next morning to an uncharged vehicle.
kkillebrew
Banned
I agree but all those NEC specs are based around 100ft run lengths hence my comment regarding a max 25ft length to maintain the correct ampacity rating. I also told him to charge at 20 amps not 24 for unmonitored/continuous use. I use one of these at a lake cabin all the time - never gets hot - less than a percent line loss. Remember it is in the open air not behind a wall...
ImI sorry, but removing a ground pin is ALWAYS a bad idea.
If you or someone else happens to use it for something else, death is quite possible
SSonnentag
埃隆•馬斯克
I have a super heavy-duty 25-foot 14-50 extension cord, but I only use it when at RV sites. As others have stated, it's not recommended for permanent daily use.
Also, these type of extension cords may cost just about as much as hiring an electrician.
Also, these type of extension cords may cost just about as much as hiring an electrician.
This is exactly what I do as it gives you more flexibility on types of plugs you can easily use. 14-50, 10-30, 14-30, etc. The cable is a little bit more of a pain to haul around as it's very thick but with a 35ft extension that is basically overbuilt I get almost no voltage drop. As you said though, the big key here is it's up to the user to manually set the charge rate to 80% of the outlet type as you are always using the 14-50 plug on the charger side.
kkillebrew
Banned
It is certainly not ideal. However lots of the non molded plugs that you use to build or repair have the option to leave it out.
SSonnentag
埃隆•馬斯克
Same thing I do, but didn't want to take flak from readers for the possibility of over-current draws, so didn't post it.
I also have a 10-gauge 15-20 extension cord with a 5-15 adapter for locations without 14-50 or TT-30 outlets.
kkillebrew
Banned
Can you explain to me the difference in electrical terms between a piece of romex in-wall and a properly sized and connected extension cord? If I give you a $1000 Fluke true RMS meter to measure with can you tell the difference if you do not know which is which? Can the car?
doghousePVD
My grandfather’s car
Rocky did NOT say to remove the ground pin. The Tesla will not charge if it does not see a ground.
Rocky said to remove the NEUTRAL pin, which does nothing when charging a Tesla. If the neutral-less extension cord was used the most likely scenario is that the device simply would not work, but not explode, get hot, or anything exciting. For example, a typical modern electric dryer might light up the LEDs, but definitely would not get hot (dry clothes), and the motor probably wouldn't start. Nothing very dramatic, but not a great idea, either.
If the cord was used in a 120V RV or trailer, probably nothing would work. Unplug it.
Death is highly unlikely, unless you were chewing the insulation off while in a metal bathtub full of water AND it is not plugged into a GFI circuit. Of course, that would be bad regardless if the neutral is attached or not.
