Electrical Issues

[brenkco]

The dealer brought out a jumper box and a 50a extension cord. Plugged me into 2 30a breakers and everything worked fine the rest of the weekend. As soon as I plugged in, the lights were bright, furnace, refer and vanity lights worked. I still don't undertand why if I was plugged into a 30a breaker, the rest of the systems shut down. I completly disconnected the 30a line, three times, flipping breakers both at the post and in the trailer.

If there was a problem with the converter, wouldn't it continued when I plugged in the twin 30's? Also, when the dealer did the PDI, we were plugged into a 30a service with a twist-type short 50 to 30a adapter plugged into the rig.

The rig is at the dealers now and when I go to pick it up, I want to futher trouble shoot the problem. I suppose it could have been the CG a/c???

[H. John Kohl]

I claim your 30 amp to 50 amp plug may be bad. As stated When using 50 amps you have two lines feeding 50 amps each. When using 30 amps you have on 30 amp line and it feeds to both 50 amp lines. If it only feeds to one then you get power to only one side. I would look at the 30 to 50 amp interface.
Good luck and let us know what you find.
Cheers,

[brenkco]

Thanks John, I'll check it out!

[MacDR50]

I did some reading and phoned my friend who maintains diesel generating stations. If I understand things correctly, John has it spot on. Your 50 amp plug/cable gives you two circuits at 120 volts 50 amps each. Notice the 3 blades and the round ground on the plug. Use a 30 amp adapter and you are only getting one at 30 amps from the plug but this is being fed to the two circuits in your 50 amp cable. Notice that it only has two blades and a round ground on the plug. Plug the "Cheater" into two SEPARATE 30 amp circuits you get two 120 volt circuits at 30 amps each because it is wired to match your 50 amp cable so these are delivered separately through the cable. Plug it into a 20 and a 30 and you get one 20 circuit and one 30 again fed to the two separate circuits in your cable. Have I got it now??

[Snownyet]

quote:Originally posted by MacDR50

I did some reading and phoned my friend who maintains diesel generating stations. If I understand things correctly, John has it spot on. Your 50 amp plug/cable gives you two circuits at 120 volts 50 amps each. Notice the 3 blades and the round ground on the plug. Use a 30 amp adapter and you are only getting one at 30 amps from the plug but this is being fed to the two circuits in your 50 amp cable. Notice that it only has two blades and a round ground on the plug. Plug the "Cheater" into two SEPARATE 30 amp circuits you get two 120 volt circuits at 30 amps each because it is wired to match your 50 amp cable so these are delivered separately through the cable. Plug it into a 20 and a 30 and you get one 20 circuit and one 30 again fed to the two separate circuits in your cable. Have I got it now??

Wouldnt 2 50 amp leads be a 100 amp service? I think its more likely 2 25 amp leads. I know Ive got a 50 amp breaker here at home for the 5er and its a double pole breaker, 25 amps on each leg.

[bsmeaton]

Snownyet,

It is truly 100A like you originally said. It is two 50A poles (standard term 50A 240VAC).

Decades ago, if you really had a nice RV, you had 30A service (1 110VAC circuit). Parts for the 30A 110VAC was commercially available, but rare.

When RVs moved on the the next step with W/D, AC, (electric fireplaces), more power was needed and 30A was the maximum available standard for 110VAC. The next logical step would have been 30A 240VAC like your dryer uses, but the industry stepped all the way up to a full 50A 240VAC like what is used in an oven/range. All parts were commercially available, however because most RVs do not use 240VAC appliances, it gets confusing to think we actually have 100A available for 110VAC equipment.

If your breaker at home is 2 - 25A poles, it would be correctly termed 25A 240VAC I believe, not 50A. Your house main service is probably 150A 240VAC, meaning you have 150A available on each leg, or 300A total power available for 110VAC appliances.

blah -blah -blah

[MacDR50]

Yup like BSmeaton said 50 amps at 240 will give you 12,000 watts of power. AxV=Watts Split into two 120 legs at 50 amps and you get 6000 on each leg. The total watts remains the same. When you plug a "Cheater" into two 30 amp plugs you get 3600 watts from each for a total of 7200 watts. This ignores loss in transmission but you get the picture.

[Snownyet]

Ok if thats the case and our rig is a 240v, does that mean when we're using a 30a 110v park receptacle with and adapter to our 50am cord we're splitting the hot leg into 2 15amp 110v legs giving a total of 240 to the trailer? Im perplexed, we stay at one place often that has 15 amp 110 and 240v 50a outlets with dryer type plugs, thinking I needed 110v I made a home depot surplus adapter block that used 1 leg of that dryer style plug and a 30a RV receptacle in a work box outlet. If Im understanding what youre saying I can use both legs from that dryer receptacle to the 2 hot legs in a 50 rv receptacle and have the correct power... right? I dont want smoke coming from my rig cause I made a boo boo and fed it the wrong voltage.

[MacDR50]

Snownyet. I am not qualified to give anyone electrical advice. These forums have a lot of good information but nothing here can substitute for the advice and guidance of a qualified electrician. I have been reading a few technical manuals and consulting with others to try and understand how such things as "Cheater" plugs etc. work. I have shared these findings here but they are my own conclusions based upon my own knowledge and research. So take everything you read as simply discussion not advice.

I strongly suggest you go to your local RV dealer and ask them for the options for connection to various CG supplies for your trailer. Any modifications using adapters etc. not specifically designed for these alternatives is playing with fire, literally.

[Dennis and Carol]

Ozz, jump in here!!! It is my understanding is with a 50A service, you have 1 20 amp leg and 1 30 amp leg. If you connect to one of the legs and a ground or common you get 110V. If you connect to both legs and a ground or common you get 220V. If this is not the case, I do not know how my 220V dryer is working on a 50 amp service. Anyway, that was the way my old Papa explained it to me. The converter is probably behind the panels in the water closet.

[bsmeaton]

Dennis,

50A service at the pedestal is two 50A legs. Two circuits that share neutral (white). Ground has nothing to do with it.

Your 2007 Monty accepts two 50A circuits from the pedestal and distributes it throughout as 110VAC circuits. (Only the pre-2004 Monties used a 30A+20A)

A meter across either 50A leg and neutral is 110VAC. A meter across the 2 legs is 220VAC. Your dryer is using both legs to get 220VAC and using the neutral as a return (RVs are not permitted to combine neutral and ground which is why they are 4 prong plugs instead of 3).

[skypilot]

Don't know 20 amp from 30 amp from 50 amp but I can tell you when the electrician and I pulled wire for my 50 amp plug at home we pulled two hot lines each of which go to the side of a 50 amp circuit breaker (2 of them - one for each line), the other side of the circuit breaker attaches to the silver bars running down the middle of the circuit breaker panel box.. oh yeah, one breaker is on one side of the box, the other on the other side so they are on separate runs from the panel as well; then we also ran a single (heavier guage wire) common wire and a ground wire -- total of 4 wires run in that conduit. When he hooked them up in the recepticle box itself, one hot, the common and the ground also feed a 20 amp circuit so I can run an air compressor or vacumn or light; that hot then ran to one leg of the 50 amp plug.

The other hot line ran to the 30 amp recepticle and then to the 50 amp; also with common and ground running to the 30 amp as well. I can NOT run 30 amp at the same time as 50 amp; and was warned to not run the 20 and 50 at the same time because I could possibly over draw that particular hot line. Since then I've pulled two more wire (in another conduit) and actually had my favorite electrical contractor separate the 20 and 30 amp recepticles off from the 50; each runs back to its own circuit breaker in the panel. All to code (actually over code from what I was last told) but I feel safer given this is at home -- When we split it out we even put a 'fire' pull outside so that the fire department could kill power to the box if need be -- something that code upgraded some time back but local authorities adopted fairly recently or so I was told.

In any case, long winded discussion to your question - sorry for the length -- but wanted to let you know that there are (or should be) two individual hot lines coming in from distinct circuit breakers feeding each of two legs in that 50 amp recepticle...

Oh my stars (cleaned up my H%ly XXXX Batman comment). -- my Big boss looking over my shoulder wondering what I was doing and he just told me his is a single 10 guage wire running from his panel to one leg of his recepticle and then jumpered across to the 2nd leg --- plus a common and ground...His comment was perhaps that is why he keeps tripping the breaker inside when he turns on his AC and Microwave... or both ACs...

[bsmeaton]

For those tech types -

Article 551, RVs and RV parks - National Electrical Code (NEC) [NFPA 70] 2008 Edition

(1) Units with One 15-Ampere Branch Circuit. Recreational vehicles having only one 15-ampere branch circuit as permitted by 551.42(A) shall have an attachment plug that shall be 2-pole, 3-wire grounding type, rated 15 amperes, 125 volts, conforming to the configuration shown in Figure 551.46(C).

(2) Units with One 20-Ampere Branch Circuit. Recreational vehicles having only one 20-ampere branch circuit as permitted in 551.42(B) shall have an attachment plug that shall be 2-pole, 3-wire grounding type, rated 20 amperes, 125 volts, conforming to the configuration shown in Figure 551.46(C).

FPN: Complete details of this configuration can be found in ANSI/NEMA WD 6-2002, National Electrical Manufacturers Association’s Standard for Dimensions of Attachment Plugs and Receptacles, Figure 5.20.

(3) Units with Two to Five 15- or 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.

FPN: Complete details of this configuration can be found in ANSI/NEMA WD 6-2002, National Electrical Manufacturers Association’s Standard for Dimensions of Attachment Plugs and Receptacles, Figure TT.

(4) Units with 50-Ampere Power-Supply Assembly. Recreational vehicles having a power-supply assembly rated 50 amperes as permitted by 551.42(D) shall have a 3-pole, 4-wire grounding-type attachment plug rated 50 amperes, 125/250 volts, conforming to the configuration shown in Figure 551.46(C).

FPN: Complete details of this configuration can be found in ANSI/NEMA WD 6-2002, National Electrical Manufacturers Association’s Standard for Dimensions of Attachment Plugs and Receptacles, Figure 14.50.

(D) Labeling at Electrical Entrance. Each recreational vehicle shall have permanently affixed to the exterior skin, at or near the point of entrance of the power-supply cord(s), a label 75 mm 45 mm (3 in. 1 in.) minimum size, made of etched, metal-stamped, or embossed brass, stainless steel, or anodized or alclad aluminum not less than 0.51 mm (0.020 in.) thick, or other suitable material [e.g., 0.13 mm (0.005 in.) thick plastic laminate] that reads, as appropriate, either

THIS CONNECTION IS FOR 110–125-VOLT AC,
60 HZ, ____ AMPERE SUPPLY.

or

THIS CONNECTION IS FOR 208Y/120-VOLT or 120/240-VOLT AC, 3-POLE, 4-WIRE,
60 HZ, ______ AMPERE SUPPLY.


The 2004 Montanas and later are configured as (4). The Pre-2004 Montana configurations are no longer recognized by NEC

[noneck]

That was like taking the NEC quick course all over again! Clearly I'm no longer recognized by NEC... That does not mean my unit is unsafe...

[ole dude]

Huh? what?

[skypilot]

I'll pull the wire, I'll even install the conduit, but when it comes to actually hooking it up, it is to the electricians I go... cost some $$$$ but I've never been allowed to do something that wasn't to code (at that time - as I mentioned above, between the time when we did the initial install and when I 'upgraded', code changed so we had to add some more to the project)... Brad cites the chapter and verse above for some of the many rules that skilled artisans abide by. What I didn't understand earlier in life is that the local communities have to adopt the national code as amended (enter dates here)(our local city government did that with various fire, construction and some others this past October). Like so much of everything we do, change is inevitable so the caveate you frequently see is so true - "Check with your local ______ as local laws and regulations may have changed".

[MacDR50]

Thanks BSmeaton. I now know I had/have it right in my own gray matter. The missing confirmation was the panel set-up in the trailer which I expected was similar to a house panel. I hadn't thought about the dryer in the RV being 220.

BTW I use 240/110 volts because that is the standard power here in Newfoundland and I think most of Canada.

[Snownyet]

Gotcha, Ive got the NEC stuff right here at my desk but I didnt think to look at the code for RV stuff. Thanks for the heads up folks, I know just what I need to do now.

[brenkco]

First, thanks again to all that contributed here. I wanted to try to conclude by giving you my findings. I pickup the rig yesterday after some minor warranty issues. I had them park me in a bay with 30a service so I could re-test all of my cables and connections prior to heading out. So here is what I found:

I plugged in my 25', 30a cable into my 30 to 50a adapter into my 50a cable into the rig, (exactly what I had done at the CG). I checked the microwave, vanity lights, ceiling fan and all were operational. At the CG, I had no ac but I proved at the dealership that the cabling was ok. I can only conclude one of 2 things, either I didn't have the cables plugged in completely or the 30a service had insufficient voltage to power the rig.

I didn't opt to purchase a 2nd 50a cord (I think it was around $200).
Thanks again! It's been an education!!!

[HamRad]

Brenkco,

Did you double check that the pedestal was turned on? I mean no disrespect; just double checking. Can't remember the number of times we've plugged in and forgotten to check whether or not the switch was turned on!

HamRad