Shore Power Questions

[Gary Hebb]

I'm new and trying to find where to enter a new post. Looking to replace 30 amp cable, plugged in cable to 240 outlet and sparks flew, no power to unit. Every other power suppy works, battery, generator, etc. Any suggestions? Can I just buy a cable at Home Depot and do it myself. tired of waiting for shops to "fit me in."

[Jammer]

The 30 amp cable is supposed to plug into a 120 volt outlet.

You can buy replacement cables at any of a number of online RV stores. Tweety's, Adventure RV, Campingworld.

[Jammer]

One question to ponder is whether you have the detachable-type Marinco cable or the hardwired cable.

[Melody Ranch]

Do not plug into 240 volts. Even though your cable plug looks like a 220/240 plug...it is not. Its is 30 AMP 115 volt. Get an adapter for the plug end if you want to plug it into a conventional household outlet. You may have already fried your electrical system. Hook up to good power and check things out..... fuses first if your lucky. You can get the cable...whichever type your replacing...at an RV shop or cheaper on EBAY....or Amazon.

[DaveFL]

You can get male 30 amp cable end but not female, you have to use a 30 amp outlet in a box, neither lowes or home depot carried it, but that might be local management.
they didn't show it on line either. something about making an extension cord carrying 30 amps not safe. Osha must have gotten to management. ;-(

[68 TWind]

Randy at Bestconverter.com has the 30amp box you need. Check his web site or give him a call.

[Elvie]

In this modern day and age of building codes, I am surprised a 120V, 30Amp plug would go into a 220V socket. Tell me it ain't so.

I would've bet a lot of money on that one!

[TG Twinkie]

The 120 volt plug will not go into a 220 volt receptacle. A common mistake made by both amature an professionals is to wire the 120 volt receptacle to a 220 volt power source. I am not aware of a single travel trailer or motor home that is wired for 220 volts. My brothers 41 foot motor home has a washer and dryer and it is still a 120 volt unit.

[TG Twinkie]

Oh! I meant to ask where the sparkes flew from. If it was just the cable, you may be OK. But if not, anything you turned on will be damaged. Hopefully you didn't try to start the AC. If it was just light bulbs they can be replaced, the fixture will probably be OK but visually check each one for damage. Most of the 120 volt wiring used in these situations is rated for 300 volts, so unless there was a direct short between the two conductors, the wiring itself will not be damaged. Good Luck!

[Jammer]

Originally Posted by TG Twinkie

The 120 volt plug will not go into a 220 volt receptacle. A common mistake made by both amature an professionals is to wire the 120 volt receptacle to a 220 volt power source. I am not aware of a single travel trailer or motor home that is wired for 220 volts. My brothers 41 foot motor home has a washer and dryer and it is still a 120 volt unit.

My trailer is wired for 110/220 volt, 50 amp service, as are many, and I have a matching shore power connection in my storage shed.

I agree though, that wiring the TT-30 plug for 220 volts is a common mistake.

[markdoane]

My trailer is 120/240V 50 amp also.
Must be a Minnesota thing. We're all power-crazy.

[wmarsha]

ac voltage in wires is pretty much meaningless, until there is an amperage draw. fuses and circuit brkrs sense amperage, not voltage. electrical devices are rated at certain voltages, and amperages based on their mfg'g materials and processes.
assuming a 3 wire 30 amp 120vac wiring/device and assuming a 3 wire 240vac circuit of ? amps (today, 30and 50 amp ac devices are 4 wire, although 3 wire 50a circuits can still be found). both circuits have 3 wires; the 120vac has a hot, a neutral(a grounded conductor), and a grounding conductor. the 240vac 3 wire circuit will have 2 hots, and a grounded conductor. The 240vac circuit was the source, so there was momentarily at least one hot lead connected to a grounded conductor. Either a wire burned (fusible link) or a circuit breaker or fuse protecting the source operated. Because the expression "sparks" was used, The wiring probably burned. I agree with the idea that a 30amp 120vac male plug should not fit into a 240vac 3 wire female receptacle, but a visit to the website: "thereIfixedIt" will showcase the amazing adaptations mankind is capable of creating. I doubt anything on the coach suffered damage, although it may have. good luck, and yes, there is a simple way to make an adapter to connect a 30 amp 120vac male plug into a 240vac 3 or 4 wire circuit. ya just gotta know how to correctly connect the wires.
ol' bill

[Jammer]

I think we scared the OP away.

[TG Twinkie]

Well, I learned something today about trailers being wired for 220 volts. But I must disagree with WMarsha. It's the voltage that penetrates the insulation of wiring. If the dielectric capacity of the insulation to withstand the potential is not high enough the voltage will penetrate the insulation. Think of voltage like you would pressure in a water supply system and the insulation of the wiring as the pressure rating of the piping in that water supply system. If the pipe is rated at 50PSI for example and the water pressure is 100PSI, the piping will not withstand the excess pressure and develope a leak. Even though there is no flow of water thru the system since all valves are closed. Voltage=Pressure: Current=Flow. You would not use wire rated a 300 volts on a system rated at a higher voltage such as 480 volts. Wiring used on 480 volt systems is typically rated at 600 volts. The voltage rating of wiring is as important if not more important than its ability to handle the current. Circuit breakers and fuses protect from over current, not over voltage. Even the black electrical tape you use for common wiring connections is rated for different voltages ie 300, 600 and higher ratings. If you have doubts about this, try using common household wiring for spark plug wires. The insulation will not withstand the high voltage produced by the ignition coil even though the relative current produced is low, typically measured in milliamps. 1 milliamp= 1/1000 amp.

[Birdwell57]

I=E/R

Increase in voltage or decrease in resistance = increase in current drawn

Over current is usually bad.

[wmarsha]

twinkie you are smack on. but, i can run a spark voltage thru a 14 ga wire as far as I want as long as there is no better conductor anywhere near the wire, especially if I make no turns in the wire. Spark voltage will jump the gap on a spark plug, but will still use a better conductor if it is handy rather than flow through open air. "they" used to run bare wires inside houses-with ceramic insulators mounted on wood. as long as nothing got across the wiring, all was well. without a current draw, there is no voltage flow, either. so the case in point had current draw, and I think it was a case of one of the grounded conductors within the shore line connected directly to a hot leg of the 240vac (which, incidentally would only be 120VAC) that caused the shore line wire to become a fusible link. At least that is what I surmise. Voltage rating of the wiring insulation is not meaningless and I apologize to the forum if I gave that impression. In order to introduce 240vac into a single conductor, you have to connect both hot legs together and then connect your single conductor to that-which should be an impossibility using plugs and receptacles. 240VAC will flow through any wire until the ampacity of that wire is exceeded; if the insulation breaks down before the ampacity of the wire is exceeded, then if there is any other grounded conductor touching said insulation, there will be a fault at that location, and possibly save the first wire from melting open. So, hopefully, the shore line fusible link in the OP's post opened BEFORE anything in the coach drew enough current to cause problems. Bottom Line: be careful plugging your trailer into any AC source. Know whatcha got before inserting the plug. here is some info on that topic:

http://www.interpower.com/ic/NEMA_configs.asp

please don't go blind looking at all of these

be cool, ol' bill

[Gary Hebb]

To all...

Thanks for all your info. My RV is parked about 200 miles from my home. Got a call tonight from the guy who built my hookup where I park on the farm. He said the diodes were fried and he did a bypass to a straight 110 connect. Taking out all the 220 plugs so no one else try's the same. I didn't ruin anything inside the RV because when I did the damage, the generator did work for me. It's 23 years old and I use it for my "motel" when I go to the farm. It's not moving anywhere, no need for a generator, just power outlet. He tried everything and it works. Thanks for all the responses received.

Gary