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Old 05-10-2019, 02:14 AM   #1
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30 amp to 15/20 amp adapters

I have seen many "dogbone" adapters that will plug into a 30 amp outlet allowing you to plug in any 110 cord or appliance. My concern is the circuit is rated for 30 amps. Unless you have a dead short downline, that 30 amp breaker is not going to trip leaving any 110 appliance vulnerable to damage or worse yet, a fire. I have not seen any 30 to 15 amp adapters with inline circuit breaker protection. Can you use this adapter then plug in a 110 GFCI adapter (that any big box store sells) between the 30 amp adapter and the appliance you are attempting to run thus having a "protected" circuit? Or will the male end of the GFCI be vulnerable because it is being fed 30 amps thus overloading that connection? It still is not the same as having a 15 amp breaker between the 30 amp adapter and the appliance you are plugging in as you would with a standard circuit panel box. Any thoughts?
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Old 05-10-2019, 03:06 AM   #2
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I do what you are asking about

I use a 30 amp to 15 amp dog bone with a in-line 15 amp circuit breaker from a big box store. It is my belief that if my appliance draws more than 15 amps, the in-line breaker will trip. This idea is the same as the many in-line breakers I have throughout my home to protect my computers and other devices from over voltages.
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Old 05-10-2019, 03:10 AM   #3
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I'm wondering why have one going that direction? Most RVer's have the dogbone to plug their RV's 30 amp cord into a 15-20 amp household plug with the knowledge their only going to get that 15-20 amps.

Most campgrounds that have 50 and 30 amp receptacles also have a couple 20 amp in the power pedestal. Most generators also have a or a couple 20 amp plugs. If I needed more, I would plug in a quality power strip. I would not own one for the reasons you mention. Just my 2 cents.
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Old 05-10-2019, 04:39 AM   #4
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Originally Posted by Ejetter View Post
I have seen many "dogbone" adapters that will plug into a 30 amp outlet allowing you to plug in any 110 cord or appliance. My concern is the circuit is rated for 30 amps. Unless you have a dead short downline, that 30 amp breaker is not going to trip leaving any 110 appliance vulnerable to damage or worse yet, a fire. I have not seen any 30 to 15 amp adapters with inline circuit breaker protection. Can you use this adapter then plug in a 110 GFCI adapter (that any big box store sells) between the 30 amp adapter and the appliance you


are attempting to run thus having a "protected" circuit? Or will the male end of the GFCI be vulnerable because it is being fed 30 amps thus overloading that connection? It still is not the same as having a 15 amp breaker between the 30 amp adapter and the appliance you are plugging in as you would with a standard circuit panel box. Any thoughts?

I'm not sure I am following your concern correctly here, if you are talking about an adapter like this that goes from a NEMA TT-30P to a NEMA 5-15R











You are not really being "fed" 30 amps, but could "draw/pull" up to 30 amps. If you plug in an item that only draws 1 amp, then only one 1 amp is going thru the cord.


To draw this 30 amps, you would need to plug something into that cord that draws that much. Since it is a singular NEMA 5-15, what are you going to connect to it that could possibly draw up to or more than 15 amps. The blade configuration won't allow you to plug anything in, that is designed for over 15 amps in the one pictured above. You would have to plug in some kind of power strip to allow multiple items to cumulatively draw more than 15 amps.


I'm just not seeing the applicable concern in this, but its still early. LOL
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Old 05-10-2019, 05:29 AM   #5
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Doing a little head scratching myself over what the actual concern is.
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Old 05-10-2019, 07:10 AM   #6
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30 amp to 15/20 amp adapters

The concern is those adapters have no power protection other than the 30 amp breaker which won't trip until you draw around 39 amps. If you have an appliance plugged in (it could be a pop-up without an A/C which requires a 110 only connection, or a tent, etc, and the 110 outlet is not working or Billy-Bob decides to use both outlets to run multiple electrical appliances) and that appliance has an internal electrical problem, that 30 amp breaker isn't going to trip leaving you vulnerable to a fire or electric shock. If you do start to draw over the rated 15-20 amp current by running too many appliances running at the same time (space heater, hair dryer, electric cooking appliances, etc), I can't imagine the 110 side of the adapter is rated to handle 25-30 amps. At that point, the 30 amp breaker won't trip but you are putting a heavy load on the adapter not made to handle that load. It may not cause a problem for the one time use but over time, it can cause a degradation of the adapter.
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Old 05-10-2019, 07:27 AM   #7
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Is it a circuit breaker or GFCI? The two are not the same. A circuit breaker detects overload while the GFCI is a device that sense a leak in the circuit between the lived conductor and the return neutral conductor. I have not found one that does both. I have not found an inline circuit breaker, only GFCIs.
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Old 05-10-2019, 07:27 AM   #8
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The technical answer to this question is that the breaker in any power system is designed to protect the wiring from the breaker to the outlet an appliance is plugged into not the appliance. It is the responsibility of the individual that would use that adapter to insure that the line from the adapter to the connected appliance(s) be sized to carry 30A. Most likely any failure in an appliance would result in a current sufficient to trip the breaker before causing damage. There could be shock issues with faulty wires, but that is no different than in a normal home and would require a GFCI. The take away here before you use this or any adapter/appliance understand the limitations and risks.
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Old 05-10-2019, 07:31 AM   #9
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All depends what your original intent to do when going 30/15amp. Good to go unless your looking to run a lot of stuff. Later RJD
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Old 05-10-2019, 07:35 AM   #10
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You are correct, a GFCI does not provide overload protection. Use of the adapter could provide up to 30 amps of current in an overload or shorted connection. It is important to use it properly.
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Old 05-10-2019, 07:38 AM   #11
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If your TT is plugged into the dogbone, the circuit would be protected by that particular circuit breaker in the panel which possibly is a 15A as well as at the pole. If you are using multiple circuits in your TT then the breaker at the power source will see more of the load. Those dogbones can get hot if overloaded I've seen where the terminals of the TT cord and dogbone have deformed due to heat/overload. I always check to see how hot the cords are. At the post in our SPs the 30A outlets have a sticker telling you 25A Max. EMSs anyone? Those adapters are probably still 12 or 14 ga for that kind of current. That's the weakest link or restriction to flow
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Old 05-10-2019, 08:10 AM   #12
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Quote:
Originally Posted by Ejetter View Post
The concern is those adapters have no power protection other than the 30 amp breaker which won't trip until you draw around 39 amps. If you have an appliance plugged in (it could be a pop-up without an A/C which requires a 110 only connection, or a tent, etc, and the 110 outlet is not working or Billy-Bob decides to use both outlets to run multiple electrical appliances) and that appliance has an internal electrical problem, that 30 amp breaker isn't going to trip leaving you vulnerable to a fire or electric shock. If you do start to draw over the rated 15-20 amp current by running too many appliances running at the same time (space heater, hair dryer, electric cooking appliances, etc), I can't imagine the 110 side of the adapter is rated to handle 25-30 amps. At that point, the 30 amp breaker won't trip but you are putting a heavy load on the adapter not made to handle that load. It may not cause a problem for the one time use but over time, it can cause a degradation of the adapter.
Ejetter, you are phrasing things in a way that I'm not sure you're understanding how this electric works.

There is actually no 120 volt side to the adapter. It's all 120 volts thru and thru. A 30 amp RV outlet (NEMA TT-30) is 120 volts only as well as a 15 or 20 amp outlet (NEMA 5-15 and 5-20). Volts and amps are two different things.



Even a 120/240 volt split phase 50 amp outlet (NEMA 14-50) is normally utilized by RV's in such a way that only 120 volts is supplied.

https://www.rvtechmag.com/electrical/chapter3.php

Although I have not looked at the true specs on these dogbones, I would be fairly confident in assuming that the entire dogbone is manufactured (including wire size) to handle up to the amount of amps it's being plugged into (in this case 30 amps) and could possibly ever draw thru it.

If you really want to blow your mind, Conntek makes one that allows you to plug into a 30 amp outlet and then has three NEMA 5-15 receptacles.

30A RV Camp Power Pigtail Adapter Cord
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Old 05-10-2019, 08:16 AM   #13
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There really isn't a problem of being protected by the larger 30amp breaker. Any problem that is going to shock or start a fire in one of your appliances is going to draw far more than 30amps... It would likely be a short- and trip the breaker.

A GFCI is designed to ensure that there is "balance" between the poles on your line. Basically, if you "short" a line by allowing current to flow directly to the ground the GFCI detects the imbalance (not enough power coming back on the neutral as is going out the hot) then it shuts power off.

The breaker really will only protect the wiring. You could potentially overload your wiring by running too many devices at once that don't exceed 30amps if your wiring is only rated to 15 or 20amps.

Think of it like pipes. How much water can flow through a garden hose vs. home much can flow through a city water pipe. You can't overload the garden hose without it bursting. But, you can certainly underload the city pipe without a problem.
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Old 05-10-2019, 02:10 PM   #14
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Quote:
Originally Posted by Ejetter View Post
I have seen many "dogbone" adapters that will plug into a 30 amp outlet allowing you to plug in any 110 cord or appliance. My concern is the circuit is rated for 30 amps. Unless you have a dead short downline, that 30 amp breaker is not going to trip leaving any 110 appliance vulnerable to damage or worse yet, a fire. I have not seen any 30 to 15 amp adapters with inline circuit breaker protection. Can you use this adapter then plug in a 110 GFCI adapter (that any big box store sells) between the 30 amp adapter and the appliance you are attempting to run thus having a "protected" circuit? Or will the male end of the GFCI be vulnerable because it is being fed 30 amps thus overloading that connection? It still is not the same as having a 15 amp breaker between the 30 amp adapter and the appliance you are plugging in as you would with a standard circuit panel box. Any thoughts?
Not to worry using the dogbone on a lesser amp circuit... Even though your RV breaker may be rated at 30 amps... you plug in that dogbone and are running on a 20amp or 15 amp circuit... that is all you'll get. When your RV goes over that 15 or 20 the breaker up the line is going to pop. So remember don't try to turn on your air conditioner when on that 15 or even 20 amp circuit. No harm done, you just kick a breaker. If using a breaker with higher than your 30 amp main you RV would kick off first. Dogbone adapters are great to carry and rarely need, but when you do at least you can run the reefer and lights, maybe the TV/DVD. Coffee pot and microwave maybe if everything else is off.
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Old 05-10-2019, 02:24 PM   #15
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I think there is some confusion in this thread.
Granted, the OP's terminology didn't help as wmtire pointed out.

The OP was concerned about using a dogbone to go from a 30a RV outlet DOWN to a 15a standard household plug and whether that would be safe since the 15a circuit would then be protected by a 30a breaker.

Some in the thread are confusing using a 15a outlet to power a 30a RV.

To answer the OP concern... a certain amount of 'common sense' must be used. Sure if you do something like plug three 1500w heaters into an extension cord connected to the dogbone are you going to have issues?... yes... but why would you?
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Old 05-10-2019, 04:51 PM   #16
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If you are worried about the 30 amps AVAILABLE at the dog bone, plug in an outlet strip that has a breaker in it.

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Old 05-10-2019, 04:57 PM   #17
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Quote:
Originally Posted by Ejetter View Post
... My concern is the circuit is rated for 30 amps. Unless you have a dead short downline, that 30 amp breaker is not going to trip leaving any 110 appliance vulnerable to damage or worse yet, a fire. I have not seen any 30 to 15 amp adapters with inline circuit breaker protection. ...

I share your concern about these 30A to(that's DOWN to) 15A adapters, ... so I installed in-line 20A fuses in the two that I use, ... when I first posted about how and my reasoning why I did that, the naysayers were many, ... along the lines of, "surely there is some form of protection there or they wouldn't sell it to the public", ... well no one could show me just where that protection is, but I CAN show you where the protection is on mine, ... the whole point is "that 15/20A line or anything plugged into it, isn't protected when the 30A breaker will allow up to 30A to get to it", ... I bought and modified those adapters after I modded my ac wiring so I can run the ac off the 120V outlet on the cg power pole and about half of those didn't work at our favorite cg after the hurricane flood, ... with a 50A to 30A adapter I plug them into the 50A outlet, ... I just wanted to let you know that you're not alone in your reasoning, having a known in-line fuse for protection for that line makes sense to me, ...
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Old 05-10-2019, 11:48 PM   #18
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Circuit breakers protect building and vehicle wiring, NOT appliances. Both the 30-amp circuit and the 15-amp circuits are typically fed by 100-amp or much higher feeds at the panel. The only difference between the 15 and 30-amp circuits are the wire size and the breaker that protects that circuit’s wiring.

Adapting from a 30-amp circuit to a 15-amp system poses no extra risk to any appliance at all and poses no risk to any RV wiring that is protected by it’s proper circuit breakers. HOWEVER, YOU CAN BURN UP ANY EXTENSION CORD NOT PROTECTED BY A CIRCUIT BREAKER if connected to a higher load than its rating. Fella10 is right about that, but there is no need to invent your own system. Many circuit breaker protected cords (aka “overload protected”) are available at reasonable prices. Here are a few:
https://www.amazon.com/Prime-Wire-Ca...dp/B000KKND4K/
https://www.amazon.com/Prime-Wire-Ca...dp/B000KKND4K/
https://www.amazon.com/Masterplug-He...dp/B01MSYP92H/
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Old 05-11-2019, 05:28 AM   #19
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I think that some 'fear' that electrical power is going to somehow 'accidentally' come rushing up into their RV and 'zap' everything!.... but that's not how electricity works.

The only 'power' that rushes 'into' your RV, when you are plugged into a 30amp, 20amp, or 15amp outlet, is 120 volts. 120 volts is 120 volts no matter 'which' of these outlets you use.

Now, AMPS is a different story, and THAT is really what you are concerned about, BUT amps are a product of what your APPLIANCE or DEVICE is 'asking' to use. If it is a small item, such as a 120v phone charger, or a small fan, then it may only be a fraction of an amp. If it is a larger device, such as an electrical space heater, your microwave, or your electric Water Heater element, then it might be anywhere from 5 amps on LOW, or up to 10 amps on HIGH - your roof Air Conditioner might draw up to 12-13 amps, or even higher when it first 'starts up'.

AMPS are the product of what YOU are using, not what the outlet is that you are plugged into. You could plug any of your devices or appliances into that same outlet directly, and NOTHING would happen. You can plug your whole RV into that same outlet, and NOTHING would happen. Only when you start USING things that require power will the AMPS being used determine if the breaker trips due to overheating, which is the byproduct of the usage of amps, and the breaker is designed to protect the wires by 'stopping' the usage of the AMPS, if so. Either the individual breaker within your RV will trip, or the Shore Power breaker will trip.

Are you concerned that the 'adapter' itself will be an issue? If so, IT would be the weak link, not your RV, and not your Appliances, though I suspect you'd never see this happen.
Millions of RVrs across the country, in many, many different power scenarios have successfully and continually used adapters of all types to 'adapt' to 120v power sources, and it's not anything to fear.

I have used a simple 'block' 30amp to 15amp adapter for many years, at home, at friends, and in situations where a regular household electrical outlet is the only option.
I also have a 50amp to 30amp adapter, for those times when at a campground or rv park with only 30amp service, for 30amps maximum power usage.
I have a 50amp to DUAL 30amp/15amp adapter, for when both a 30amp and a 15amp outlet is available, for a maximum of 45amps of power usage.
I have a 50amp to DUAL 30amp adapter, for those times when there is access to TWO 30amp outlets at the same time, for 60amps maximum power usage.

it's great, it's great options... don't sweat it.
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Old 05-11-2019, 11:49 AM   #20
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50A to 15/20A ok?

I've been reading this thread with great interest. I am gearing up to purchase a portable A/C unit to augment the single roof A/C in our 30A Class C. Obviously I cannot plug it into an interior receptacle, so the plan is to mount an outside receptable like this:
https://www.amazon.com/dp/B000NV0V8C/
back near the wetbay and then run a heavy duty extension cord over the shore power pedestal in the park and connect it to the routine 15/20A outlet there.

I have a whole elaborate plan to vent the portable A/C to the outside, but that's a separate thread. My question here is simply about power supply and lots of knowledgeable people in this thread to ask, so my question is simply this. Since I will be using the 30A outlet on the pedestal for the primary coach connection I would be using the auxialiary 15/20A outlet for the portable A/C but recently I was in a park where they ONLY supplied 30A and 50A - no 15/20A outlet at all. So I would want to connect to the 50A outlet with something like this:
https://www.amazon.com/gp/product/B078XBC37F/
Then run a heavy cord over to the new exterior outlet on the coach using a 12/3 cord like this:
https://www.amazon.com/gp/product/B004J3DEAC/

From what I read in this thread, it should be fine, but just like to make sure, since no one is eally talking about con erting the 50A to 15/20A. Anyone see any problem with this? Thanks in advance....
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