"Shore Power" question

[teddyu]

Originally Posted by hohenwald48

Every chance I get I try to discourage folks from getting their shore power electrical advice from this forum. Most info is wrong at best and often down right dangerous.

I know of at least two motorhomes where the smoke has been released due to improperly installed standard 30A RV outlets. In both cases, different licensed electricians installed the outlets but wired the RV outlet like a 240VAC dryer outlet. If folks wo do it for a living make those kinds of mistakes, just imagine the havoc caused by folks who get their electrical apprenticeship on a web forum. [emoji2962][emoji2957]

I agree whole-heartedly with this posting. A lot of BS has occurred in this thread and IT IS VERY DANGEROUS. Very rarely do you get a second chance with a shore-power wiring screw-up. Just my 2cents.

[dmwoody]

Wow. I'm not an electrician, but I find it pretty simple. L1, L2, N, G. Manufacturers of adapters understand all that to the extreme, and can sell you anything to adapt any voltage source to what you need. 30A 240V to a 15A 110V, 30A 110V gen to a 30A 110V RV, etc ... Buy the adapter you need. Getting an outlet installed does take additional knowledge of how to have it wired correctly. But the principles remain the same - L1, L2, N, G. And then there's bonding and why you can't use a GFI to plug into.

[Jkwilson1989]

Originally Posted by dmwoody

Wow. I'm not an electrician, but I find it pretty simple. L1, L2, N, G. Manufacturers of adapters understand all that to the extreme, and can sell you anything to adapt any voltage source to what you need. 30A 240V to a 15A 110V, 30A 110V gen to a 30A 110V RV, etc ... Buy the adapter you need. Getting an outlet installed does take additional knowledge of how to have it wired correctly. But the principles remain the same - L1, L2, N, G. And then there's bonding and why you can't use a GFI to plug into.

How do the people who make adapters know how dryer outlets are wired?

Many have neutral and ground bonded at the plug, but some had no neutral and relied on the ground as a neutral conductor. Is there an adapter that somehow creates a neutral wire to the service panel where none exists?

It's also common and permissible by code to undersize a neutral when the primary load is going to be equally balanced between the lines. Is there an adapter that can increase the size of the neutral wire in the walls to make it safe for unbalanced loading?

Using an adapter to connect a different load to a dedicated outlet without understanding the wiring is dangerous.

[wolfe10]

Originally Posted by dmwoody

Wow. I'm not an electrician, but I find it pretty simple. L1, L2, N, G. Manufacturers of adapters understand all that to the extreme, and can sell you anything to adapt any voltage source to what you need. 30A 240V to a 15A 110V, 30A 110V gen to a 30A 110V RV, etc ... Buy the adapter you need. Getting an outlet installed does take additional knowledge of how to have it wired correctly. But the principles remain the same - L1, L2, N, G. And then there's bonding and why you can't use a GFI to plug into.

NO, NO, NO. No such thing as an RV with 30 amp 240VAC. But I guess this advice is great for any unemployed RV electric guys.


BTW, so we all know what we are referring to, please state MALE XX to FEMALE YY adapter.

[Oilburner53]

Originally Posted by AJMike

OK. I did not actually check the configuration of the plugs, so I guess I could not have plugged the pigtail into the outlet in any case.

Still, my main question remains. Am I not correct in assuming that a 50 amp to 30 amp pigtail will pull 110 volts out of a 220 volt outlet (or 120 volts out of a 240 volt outlet)? And if I had an adapter so that I could plug the pigtail into the dryer outlet, would the power be OK for a 30 amp RV?

There is a difference between two legs of 120v out of your house panel and those in an RV park, or shore power. Your house gets two separate legs of 120v that are different phases. When you install a 50 amp double or 2-pole breaker into a house panel it connects to the two separate phase legs creating 240 volts across the two legs of that breaker. This is what's needed for dryers, residential ovens and ranges and electric water heaters. If you plug into this by somehow adapting your shore power plug you will energize your RV breaker panel with 240 volts. NOT GOOD! This will fry TVs, refrigerators, microwaves, etc. An RV 50amp outlet is two sources of 120 volts from the same phase so you still only get 120 volts, not 240 volts. This may seem a little confusing but trust me and a few others on this thread when we say DON'T use a standard 240 volt dryer outlet. It will get very expensive!

[twinboat]

Originally Posted by Oilburner53

There is a difference between two legs of 120v out of your house panel and those in an RV park, or shore power. !

No there is not !

There is no difference in Home and RV park electric, and everything else in your post is wrong because of your opening statement.

Please read one of the often posted links explaining this.

https://www.myrv.us/electric/Pg/50amp_Service.htm

[sctalbott]

Yes you can. 3 prong 240v outlet has 2 120 legs and 1 ground. What these adapters do is use the ground as a neutral which is basically the same as a neutral. Only problem is if your running lots of amperage on both 120v legs it can overload the ground.

[sctalbott]

Originally Posted by Oilburner53

There is a difference between two legs of 120v out of your house panel and those in an RV park, or shore power. Your house gets two separate legs of 120v that are different phases. When you install a 50 amp double or 2-pole breaker into a house panel it connects to the two separate phase legs creating 240 volts across the two legs of that breaker. This is what's needed for dryers, residential ovens and ranges and electric water heaters. If you plug into this by somehow adapting your shore power plug you will energize your RV breaker panel with 240 volts. NOT GOOD! This will fry TVs, refrigerators, microwaves, etc. An RV 50amp outlet is two sources of 120 volts from the same phase so you still only get 120 volts, not 240 volts. This may seem a little confusing but trust me and a few others on this thread when we say DON'T use a standard 240 volt dryer outlet. It will get very expensive!

This is not true.

[joelsplace]

Yes you can get 120 from a 3 wire 240 outlet. It is no longer up to code but lots of air compressors and welders etc did it for years. One of the hots to the ground gives you 120. Most old driers I've worked on use 3 wire plugs and the timers are 120V. Check the wires coming into your house from the power company. I'll bet there are only 3.
I think it is funny how Persistent took the time to spell it all out and so many just ignored him.

[sctalbott]

Another thing, your home and all RV park power is single phase. Someone said 3 phase. When we are talking about RV and home power just remember it’s all single phase. 3 phase is only available for commercial use. Our 4 prong 50 amp RV plugs are wired the same as a 50 amp 4 prong dryer plug. The ground is different looking that’s all. Good Luck out there guys. Be safe. Don’t mess with 240v unless your sure of what you are doing.

[bhale]

3 phase is only used in commercial applications. R V applications only use single phase.

Originally Posted by AJMike

I recently had the converter/charger in our RV changed from a WFCO to a PD version because the WFCO did not support charging Lithium batteries. Part of that installation included draining our batteries to make sure the new converter/charger was working properly and when we got the RV back home the batteries were very low. I plugged the shore power line into the 110 outlet in our garage as I normally have done, but it blew the circuit breaker, and plugging it into other outlets gave me the same result. Apparently the new charger, at 60 amps, was just drawing too much power for our 110 outlets, given how low our batteries were.

In a conversation with the installer I mentioned that I was thinking about using the 50 amp to 30 amp pigtail we carry with us in case we need it and plugging it into our electric dryer outlet and using that as our shore power, but the installer told me that that was a very bad idea and might burn out some of the electronics in the RV. That sounded pretty far-fetched to me, but then I am not familiar with electric wiring and figured that prudence was probably a smart choice. Still, I do want to know.

Is there any reason I should not use the 50 amp to 30 amp pigtail in our dryer outlet? As far as I understand the 50 amp outlets in RV parks are 220, 3 phase, as are the electric dryer outlets.

[twinboat]

Originally Posted by sctalbott

Yes you can. 3 prong 240v outlet has 2 120 legs and 1 ground. What these adapters do is use the ground as a neutral which is basically the same as a neutral. Only problem is if your running lots of amperage on both 120v legs it can overload the ground.

No, it will not overload the ground/neutral.

It is not two 120 volt lines !

Its one 240 volt service, split at the RV breaker box, to two 120 volt legs. Both legs SHARE the neutral, ONLY carrying the difference between the legs.
If both legs are drawing 50 amps, the neutral is carrying 0 amps.

Here is a link.

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

[teddyu]

Originally Posted by sctalbott

Another thing, your home and all RV park power is single phase. Someone said 3 phase. When we are talking about RV and home power just remember it’s all single phase. 3 phase is only available for commercial use. Our 4 prong 50 amp RV plugs are wired the same as a 50 amp 4 prong dryer plug. The ground is different looking that’s all. Good Luck out there guys. Be safe. Don’t mess with 240v unless your sure of what you are doing.

I totally agree with this comment. Readers need to be wary of shore power posts. Many contributors are posting false or untrue statements as facts. BS concerning electricity is dangerous to the unknowing or unsure. There are many websites that provide a primer on RV electrical circuits. Be safe. Read and understand these educational articles, before attempting ANY of the advice posted on this or any other RV forum. Basically buyer beware!

FYI: In my travels I have run into weird cg configuations. One cg pedstal had the same 120 line connected to the 50a receptacle, 0vac between the 2 hots. RV was ok since my unit does not use 240v. This pedstal had two 50a breakers for the 50a receptacle and one of those breakers fed the 30a receptacle. Figured it was a cheap upgrade to an original 30a pedstal. Just my 2cents.

[wolfe10]

Originally Posted by Oilburner53

There is a difference between two legs of 120v out of your house panel and those in an RV park, or shore power. Your house gets two separate legs of 120v that are different phases. When you install a 50 amp double or 2-pole breaker into a house panel it connects to the two separate phase legs creating 240 volts across the two legs of that breaker. This is what's needed for dryers, residential ovens and ranges and electric water heaters. If you plug into this by somehow adapting your shore power plug you will energize your RV breaker panel with 240 volts. NOT GOOD! This will fry TVs, refrigerators, microwaves, etc. An RV 50amp outlet is two sources of 120 volts from the same phase so you still only get 120 volts, not 240 volts. This may seem a little confusing but trust me and a few others on this thread when we say DON'T use a standard 240 volt dryer outlet. It will get very expensive!

As all have said, WRONG.



I hate it when incorrect facts are posted on electrical threads. These are FACTS. No room for OPINIONS or SPECULATION.



Both house and RV 50 amp service are exactly the same:


TWO hots (L1 and L2)
ONE neutral
One ground


30 amp RV service is just one hot, neutral and ground. Exactly the same as any 120 VAC outlet or appliance in residential service.