30 amp in a 50 amp site

[Parker]

I did the same, but started with a #14 extension cord from Lowes, 10' long I think. I cut off the female connector and installed the twist lock available from a variety of RV and marine sources. It's really handy for when we have the Escape at home or in storage and just need a little power for the fridge or charging the battery.

[NJ Joe]

Since a lot of the Escape trailers have the EMS, I figured it would be a good idea to get some direct input from progressive on this. While the response does not really support my position, or provide complete clarification, I am posting it here for the benefit of the group. My concern would be with the "As long as you don't exceed 30 amp current draw" constraint.

Email exchange:

As long as you don't exceed 30 amp current draw. Regards, Donald, Customer Support

-----Original Message-----
From: Joe
Sent: Thursday, October 23, 2014 2:47 PM
To: Donald Kalinowski
Subject: Re: question regarding the EMS-HW30C

Is there any concern with the #10 wire being protected by a 50A breaker ?

On 10/23/2014 02:45 PM, Donald Kalinowski wrote:
> yes
>
> -----Original Message-----
> From: Joe
> Sent: Thursday, October 23, 2014 2:44 PM
> To: Info
> Subject: question regarding the EMS-HW30C
>
> Can a camper with an EMS-HW30C be safely connected to the 50A connection at a camp site utilizing a 50A to 30A adapter cable at the power post ?
>
>
> thanks
> joe
>

[cpaharley2008]

That is more or less common sense with any electric use, your weakest link is normally your wire, just like someone using an electric heater with an inadequate extension. I however feel that there is little possibility you can exceed the 30 amp wire capacity in your Escape unless intentionally done.

[Brian B-P]

Originally Posted by Parker

Interesting thought. I made up a #14 power cord for plugging in to a 20 amp outlet when I don't need to run the air conditioner, rather than drag out the 30 amp cable. So if I run my light duty power cord, made with #14 wire, to a 20 amp plug into a couple of adapters to connect to a 50 amp service, my power cord may be the fuse in the circuit. I don't know why I would want to do that, but I can picture a pretty spectacular result!

Yes that could be bad, because you can draw a continuous (not just brief short-circuit) current of less than 30A (so the trailer's main breaker doesn't trip) but more than the 14-gauge cord capacity.

This is a scenario to be really cautious about; it is not like the original poster's question about plugging a 30A trailer into a 50A campsite. I would use this setup only if I were sure I would not be using any significant power. It would be prudent in this case to turn off the circuit breaker in the trailer for the air conditioner, and for any other circuit which is not needed, to reduce the chance of an accidental overload if you forget that you only have the skinny cord. If only one 15-amp circuit is left on, the load is safely managed to match the 14-gauge cord.

Originally Posted by NJ Joe

If the 50A breaker can provide adequate protection for a 30A trailer, why do campgrounds have a separate 30A breaker instead of just tying the 30A receptacle to the 50A breaker to reduce costs.

As explained earlier, the 50A breaker provides adequate protection for short circuits, not for continued use. If someone plugs anything using more than 30 amps into the 30-amp receptacle, the 50-amp breaker would not prevent overloading of that receptacle.

Originally Posted by Vermilye

I made one of these as a way to use a light cord when plugging into a 15/20 amp receptacle. It also gives me a practical way to carry a spare Marinco twist lock connector since that can be difficult to replace on the road.

I did the same, for another trailer with 50-amp service (not our Escape-sized trailer with 30-amp service, but the idea is the same). Like Parker I used an extension cord, and replaced the female connector end with the Marinco twist-lock, but I used a very short one; I only use the resulting adapter with a regular extension cord.

[Brian B-P]

Originally Posted by cpaharley2008

I however feel that there is little possibility you can exceed the 30 amp wire capacity in your Escape unless intentionally done.

I can see it accidentally occurring - most likely from cooking with electricity (microwave, kettle, toaster) especially while running the air conditioner. The 30-amp main breaker in the Escape is there to prevent this from being a safety risk.

[Brian B-P]

As for sites with only 50-amp receptacles and no 30-amp (so you would need the adapter)... yes, I've seen that. Carrying the adapter makes some sense, but on the other hand 30-amp sites seem much more common than 50-amp in most of the areas I've been in. It certainly varies by location and type of campground/park.

[Vermilye]

I've had to use a 50 amp to 30 amp adapter in a few sites on my last trip - out of 119 campgrounds, I found 3 that were 50 amp only. I also used it a couple of times when the 30 amp receptacle was badly worn & the 50 amp was in better shape.

[C&G in FL]

I'm going to go out on a limb here, but using a cord rated for 20 amps (#12 wire) to pull more than 20 amps from a 50 amp plug is not going to damage the 50 amp circuit nor will it pop the 50 amp breaker. The most likely scenario is that the 20 amp rated cord will heat up, possibly to the point that it will melt, which would likely create a short circuit that would pop the 50 amp breaker when the hot conducted comes in contact with the neutral line. Unless the cord is sitting on dry grass which could catch on fire, the only likely casualty would be (destruction of) the 12 gauge cord because the 30 amp main breaker in the trailer will not do its job until it's capacity is exceeded. Exceeding wire capacity in the confines of enclosed walls in houses can have potentially serious fire consequences. Even the plug on a window air conditioner can get warm to touch. When it gets too hot to touch, the wire's capacity has been dangerously exceeded. The real danger is electrocution. Should the insulation melt without shorting out and popping the 50 amp breaker and someone contacts bare conductors, well, someone gets shocked. The safest thing to do is to use the 30 amp cord to match the capacity of the trailer's 30 amp main breaker. If it is plugged into a 20 amp circuit and the 20 amp circuit's capacity is exceeded, it's breaker should pop. And it is doubtful this would happen unless the A/C and some other big draw device were in use at the same time. If there were no 30 amp outlet and I had a choice of 50 amp or 20 amp, I personally would use the 20 amp with an adapter. No big deal if I pop the 20 amp breaker. Just don't run everything at the same time.

[Ron in BC]

What's that expression Jon? Great minds....

Ron

[Brian B-P]

Originally Posted by C&G in FL

I'm going to go out on a limb here, but using a cord rated for 20 amps (#12 wire) to pull more than 20 amps from a 50 amp plug...
The safest thing to do is to use the 30 amp cord to match the capacity of the trailer's 30 amp main breaker...
If there were no 30 amp outlet and I had a choice of 50 amp or 20 amp, I personally would use the 20 amp with an adapter. No big deal if I pop the 20 amp breaker. Just don't run everything at the same time.

I agree that a 20-amp cord with up to 30 amps of load is a bad combination... but to me that doesn't lead to choosing the 20-amp receptacle over the 50-amp: using the 50-amp receptacle with a suitable adapter to the trailer's 30-amp cord means everything is within its rated capacity, and there is no need to specially limit how much electrical power is used.

[Ron in BC]

Originally Posted by Brian B-P

using the 50-amp receptacle with a suitable adapter to the trailer's 30-amp cord means everything is within its rated capacity, and there is no need to specially limit how much electrical power is used.

Well you can do it and common sense sort of tells you that it ordinarily wouldn't be a problem it does go against electrical codes. The breaker on a circuit is sized for the wire it protects. It's OK to use a larger diameter wire than the circuit breaker is rated for but to meet code it's not OK to use a smaller diameter wire than the circuit breaker is rated for.

Ron

[C&G in FL]

Originally Posted by Brian B-P

I agree that a 20-amp cord with up to 30 amps of load is a bad combination... but to me that doesn't lead to choosing the 20-amp receptacle over the 50-amp: using the 50-amp receptacle with a suitable adapter to the trailer's 30-amp cord means everything is within its rated capacity, and there is no need to specially limit how much electrical power is used.

Actually, Brian, I only say that because I live in the south, have to run the A/C much of the time, use a microwave, and have never popped a breaker when doing this on a 20 amp circuit. So I have not found 20 amps to be limiting, at least in my case. That being said, I would have no qualms if I had no choice but to use a 50 amp connection. If I've never popped a 20 amp breaker, I seriously doubt I'm going to pull amperage which exceeds the 30 amp rated shore power cord if connected to a 50 amp source.

[Brian B-P]

Originally Posted by Ron in BC

The breaker on a circuit is sized for the wire it protects. It's OK to use a larger diameter wire than the circuit breaker is rated for but to meet code it's not OK to use a smaller diameter wire than the circuit breaker is rated for.

As described earlier, this is a normal situation for every household lamp with a 16-gauge (or even 18-gauge) cord - except that those lamps don't have any kind of overcurrent protection (circuit breaker or fuse), and the trailer does. Since those cords can't handle 15 amps, that must be "not OK"... that doesn't make sense to me.

[Donna D.]

Hummm, you go to plug into the power pole and the cord will fit or it won't. If it doesn't... get out the adaptable and put that between the trailer cord and the connection. Power? yes.. score! Not... reset the power box. That doesn't work? Contact the host...

Seems simple to me. What do I know? Has always worked for me. YMMV

[C&G in FL]

Originally Posted by Brian B-P

As described earlier, this is a normal situation for every household lamp with a 16-gauge (or even 18-gauge) cord - except that those lamps don't have any kind of overcurrent protection (circuit breaker or fuse), and the trailer does. Since those cords can't handle 15 amps, that must be "not OK"... that doesn't make sense to me.

And just about every other electrical appliance made. Few have cords with conductors that meet the electrical code for the circuit into which it is plugged. But that is not a problem because the cord is only supplying the appliance and is sized adequately by the manufacturer of the appliance to meet its amperage requirement. The circuit wiring is intended to supply multiple appliances with various amperage requirements. Again, theoretically, a 30 amp shore power cord could be overloaded by plugging it into a 50 amp outlet, but it would require plugging a lot if additional appliances into the various trailer outlets, and if total draw exceeds 30 amps, it would pop the trailers main breaker, stopping current flow anyway, thereby protecting the shore power cord. So I would agree with you Brian, but people have to be "comfortable" with what they do. If someone has concerns about plugging into 50 amps, then don't do it.

[Ron in BC]

Originally Posted by Brian B-P

this is a normal situation for every household lamp with a 16-gauge (or even 18-gauge) cord - except that those lamps don't have any kind of overcurrent protection (circuit breaker or fuse), and the trailer does. Since those cords can't handle 15 amps, that must be "not OK"... that doesn't make sense to me.

I guess you could say that the wire size to a device is sized by the manufacturer for the amperage draw of that device. That same 18 ga. wire to a 3/4 hp motor would fry. But you're right, unlike automotive circuits that often have fuses of many varied sizes, including some for very low amperage and smaller wires house wiring doesn't do that and it would be possible to fry something without tripping the 15 amp circuit breaker.

Donna; Yes, adapters do work but it is possible to adapter your way into trouble. Remember in the old days, people put a penny in the fuse holder, it worked too but sometimes it burned the house down.

Ron

[rbryan4]

Originally Posted by Donna D.

Hummm, you go to plug into the power pole and the cord will fit or it won't. If it doesn't... get out the adaptable and put that between the trailer cord and the connection. Power? yes.. score! Not... reset the power box. That doesn't work? Contact the host...

Seems simple to me. What do I know? Has always worked for me. YMMV

In a sense, that's correct. Why overcomplicate it?

[C&G in FL]

This entire "question" can be resolved in one word: lawyers. Seriously, does anybody out there believe that if 50 to 30 amp adapters or 20 to 30 amp adapters violated the electrical code the product liability lawyers wouldn't be climbing all over it? And no major retailer like Walmart or Camping World would sell them. Not would any trailer manufacturer supply the as accessories. I, for one, cannot recall seeing a television advthat asks "Did you or one of your family members get harmed by using an adapter on your RV power cord? Did your property get damaged from using one? If so you might be entitled to compensation. Call the law offices of Dewey, Cheatum, and Howe."

[NJ Joe]

I did a little more digging online, and found both sides of the argument presented, but no authoritative source of information referenced by anyone on either side of this, only opinion. Carl's description in #35 just about had me convinced that looking at this as an appliance was the right way to look at this.

I decided to take a look at the code section 551, which specifies requirements for travel trailers.

551.40 120-Volt or 120/240-Volt, Nominal, Systems .40 120-Volt or 120/240-Volt, Nominal, Systems.

(B) Materials and Equipment. Electrical materials, devices, appliances, fittings, and other equipment installed in, intended for use in, or attached to the recreational vehicle shall be listed. All products shall be used only in the manner in which they have been tested and found suitable for the intended use.

Based on this it would appear the the code requires the adapter to be a listed product. I have found listed adapters to convert a 30A trailer to 20A plug, but have not found listed adapters of the type we are discussing here. The code also specifies the plug that should be used when attaching to a power supply:

551.46 Means for Connecting to Power Supply .46 Means for Connecting to Power Supply.
(C) Attachment Plugs Attachment Plugs.
(3) Units with Two to Five 15or 20-Ampere Branch Circuits. Recreational vehicles wired in accordance with 551.42(C) shall have an attachment plug that shall be 2-pole, 3-wire grounding type, rated 30 amperes, 125 volts, conforming to the configuration shown in Figure 551.46(C), intended for use with units rated at 30 amperes, 125 volts.


Also, related to viewing the camper as an Appliance section 551.43 provides some insight, although it is not directly applicable. It says if a single appliance is intended to be plugged in, the over current protection should not be more than 150% of the load, or in the case of a 30A load, 45A breaker.

551.43 Branch-Circuit Protection .43 Branch-Circuit Protection.
(A) Rating. The branch-circuit overcurrent devices shall be rated as follows:


(2) Not more than 150 percent of the rating of a single appliance rated 13.3 amperes or more and supplied by an individual branch circuit

I do not really expect the above to change anyone's opinion related to the safety of using the adapter, and not sure it will prevent me from having one as a backup. I think in my case I would only leave things powered up in this configuration while I am actively monitoring the situation, probably only to recharge batteries or temporarily run the AC.

[C&G in FL]

I really don't think that is applicable to the situation at hand. First, breakers are designed to trip to prevent too much amperage from melting the wire and starting a fire. Even if you were plugged into a 1,000 amp outlet, the main breaker in the camper will trip if 30 amps is exceeded. Look at the main breaker in your house panel. More likely than not it is a 200 amp entry. It feeds all the other breakered circuits, most of which are 20 amp with the stove, dryer, A/C, etc. being more. 200 amp is way more than 50% greater than 20 amps. In reality, the only way you could melt the RV shore cord is if you bypassed the RV's main breaker and then exceeded its 30 amp rated capacity, and even then it might get hot but not melt down. Furthermore, the cost to wire each drop in a campground would be prohibitive. So the distribution circuits are likely greater than 30 amp, and the box where you plug in has a breaker to limit the higher amperage supplied to the outlet to 30 amps. Not that it matters, but 50 amp campground is 220 volts. When you use the adapter, it draws from only one leg of the 220. Theoretically, if enough 50 to 30 amp adapters were being used, it could "unbalance" one phase of the power being supplied to the big stickies that utilize 220 volt power. But I would personally use a 50 to 30 adapter if only 50 amp service were available.