Adding Circuits AC stranded or solid

[Tony S]

Hi Folks. I am hoping someone can help. I have added 2, AC 20 amp circuits to my 73 Tradewind. I ran the 12 gauge stranded wire in non metalic flex conduit.

I have received conflicting advice from two different qualified sources I respect. It isn't that they said I was wrong or right but it was a matter of degree in which they favored as the correct way. One felt the stranded was great for the trailer situation (an electrician). The other felt solid was better mostly because AC devices are looking for solid wire.

I am wonder how others feel and would appreciate any input you are willing to provide.

Many Thanks

Tony

[TG Twinkie]

Typically solid wire like Romex is used for the AC side of life. Stranded wire is used for the DC side of life.
There are those that recommend only marine grade wire for everything.
Crimp type connectors are routinely used in the wiring of an RV. This type of connector works best on stranded wire.
Wire nuts typically are used on solid wire. But are known to be used on stranded wire.
One must keep in mind that stranded wire is nothing more than a bunch of solid wires in a sheath. While much more forgiving. If not supported or protected properly can also be subject to damage by vibration.



Sent from my iPod touch using Airstream Forums

[lewster]

Being 'one of those' that recommends the use of marine grade stranded cable for everything, I have seen enough breaks in solid copper Romex used in RV's over my 14 years in this business to fully justify the use of marine cable.

And for the breaking issue, try a little experiment yourself: grab a single wire 12" piece of 12AWG Romex and a similar piece of 12AWG stranded, tinned marine cable and bend them back and forth to simulate unsupported bouncing inside the wall of an RV. I will send you a $100 check if you can prove to me that the stranded cable breaks at all before Romex will. I'm sure you will find that the Romex will break well before the marine cable (I am not talking about residential stranded cable here), if you can even get the marine cable to sever.

Boats and RVs are very similar in the way they are used (either bouncing down the road or bouncing thru the waves) and the ABYC (American Boat and Yacht Council) that writes the marine standards forbids the use of any solid copper cable in boats. Why should RVs be any different?

Marine cable does cost more, but you will never experience a wire break or corrosion of any kind. And wire nuts work well also (I always tape any wire nutted connection), and you will appreciate the ease of running the flexible marine cable.

As far as your 'qualified' source stating that AC devices are 'looking' for solid wire, I would love to know what the source of that advice is. The movement of electrons form electricity, and those electrons have actually been found to move on the surface of the conductors that carry them, so in reality, stranded cable will have more surface area and the ability to carry more electrons.

Any AC device doesn't 'care' how it gets it's required electrons for proper operation, it just needs the right amount. Be certain that your cables are of the right size to carry sufficient amperage to the device, and size your over-current protection (circuit breakers and fuses) to the wire gauge used in that circuit (14AWG =15 amps, 12AWG = 20 amps) and realize that the breakers and fuses are thee to protect the wire from an over-current event.

Be safe out there and do the job right the first time.

[FishinHatteras]

I second Lewster's comments above. They are 100% correct. As far as the check is concerned, that's on him!
Having owned boats and been in the boating industry all of me life, he couldn't have said it better.

Not sure what your other source's background is that said solid wire is better, but that applies to non-moving electrical circuits, such as your house, NOT an RV. If he were to re-think his remarks geared towards the APPLICATION, I'm sure he would arrive at a different conclusion. Each form (solid wire or stranded) has it's applications, and industry standards. The old adage "voltage burns, amperage kills" can apply here. In that I mean, do not skimp on the wire size. Follow the standard & Lewster's advice above for a worrysome & trouble-free installation.
Like I heard for 5 yrs as a generator mechanic in the military: "Come correct, or don't come at all."
Gavin

[Tony S]

Thanks for taking the time to reply. My cousin, an accomplished electrician and not in my will, said the same thing as you folks. I just wanted to be sure since I already went with stranded. Unfortunately it was not marine. It was 12 gauge, for 20amp breakers.

I think what the other source (not my cousin) was thinking when he suggested solid for AC was how it actually hooked up to the breakers and outlets. He was humble and did defer to the pro's saying "he was just a dude on the internet"

Many thanks for helping me stay out of trouble.

Tony

[dkottum]

Stranded copper for trailers, boats and aircraft. My first career was as aircraft electrician (Navy), no solid wire used for AC or DC circuits. It would eventually fail in the constant movement.

[Aerowood]

Stranded for AC and DC. I'm using shielded twisted pairs and triples aviation wire, with all grounds returning to split common ground buses, one for AC and one for DC.

[B_Pi]

Stranded for flexibility. Tighten terminations. Tighten again.

[D Bishop]

Having been a Master Electrician for some 40 years, here is my take. The stranded is better for a trailer as it tolerates vibration better. The system cares not what type wire us use but the stranded will take the vibration so this is my advice for what it is worth.

[DaveFL]

As long as the stranded isn't soldered to make solid and a crimp connect is used was the better advice of the 'qualified' sources. Too much movement of either wire would be a problem. Last problem I had was with unexpected broken wires I found in the new indicator led's china thinks shrink wrap over insulation will suffice, maybe it would if connecting wires were thicker than hair.

[NavyCorpsman]

Stranded is the better choice, and is about the same in cost per foot. Use the Carflex/Nonrigid sheathing with the correct connectors to the gang box or the outlet.
Peace of mind is priceless. Like I've heard before, " Do It Once, Do It Right, or Do It Over". Merry Christmas!

[mandolindave]

I would NOT use the push in connections on the outlet. I like to tin the ends of stranded wires.

[tinbender]

Originally Posted by mandolindave

I would NOT use the push in connections on the outlet. I like to tin the ends of stranded wires.

The stranded vs solid wire debate seems to come up often but the part that usually doesn't get addressed is the method/s to use if the ends of stranded wire are going into a 120 volt circuit breaker. Is tinning the preferred choice in that situation?

What say the "sparkies" in the crowd ??? ....

[rmkrum]

If you do tin the ends of the wire, you should still put it under the screws. The push-in connections are only for solid wire.

That said, stranded wire is still best for use in a mobile situation like an AS.


Sent from my pocket Internet using Airstream Forums

[Aerowood]

I have crimped on a male spade connector and then used it under the clamping screw in the past

[Gnorts]

Solder isn't a great idea either. By definition, rosin core solder used in electrical work is an alloy, and alloys contain dissimilar metals which can present problems in an environment where condensation is an issue - in the bilge of a boat, or between the inner & outer skins of an Airstream. Condensation can accelerate corrosion in soldered joints. ABYC, the boating standard, limits use of soldered connections. If used, they must be encapsulated in adhesive heat shrink. Also, ABYC strictly prohibits the use of wire nuts, in addition to solid core wire. Wire nuts are really designed for solid core wire, even if they work reasonably well on stranded wire. The threaded insert in most wire nuts is steel, which is harder than copper and will bite into the wire, keeping the wire nut secure. But, again, in a moist environment, corrosion will be accelerated between the two dissimilar metals. Plus, if a wire nut is oriented so its open end is pointing up, any condensation that runs down the wires will end up inside the wire nut.

So, stranded wire is the recommended type in our applications. Both AC and DC. RV builders use romex because it's cheap, and it's quick to assemble the terminations at outlets and breakers that are designed to simply push a solid wire into a hole. Stranded wire shouldn't be tinned and shoved into the hole. All receptacles normally also have screw terminals. The wire should be terminated in a ring lug (preferable to a spade lug; if a screw comes loose, a spade lug can fall out of the connector) that's properly crimped on the wire.

btw, don't use a cheesy cheap-o crimper. Get a good one that will make solid crimps and last more than a week. Something like this:



And, if you really want to split hairs, buy your tinned wire and tinned crimp connectors from the same vendor - that way, the final connection will contain no dissimilar metals at all. Ancor is a good brand, available at most marine supply stores like West Marine, Defender, etc.

This info is brought to you by a former marine electric business owner, and retired marine surveyor certified in ABYC standards...

[Tony S]

Thanks for all the help. It is especially good when you find out you didn't blow it and have to do it over. Also nice when it comes to advice for electrical or propane project that some folks give their credentials. Truth I have followed the forums long enough to recognize a bunch of your names. Again many thanks.

Merry Christmas

Tony

[KrisE MN]

I found chewed wires today so doing the wiring too. I'm used to housing wiring where there's a positive, negative and ground. The wire I'm seeing is just one grouping in strands under a sheath. I've been reading online and watching youtube, but can't find the answer so I'm here... sorry. I'll look further but was hoping someone could help me ... am I looking for a one negative another stranded/positive with a ground inside a sheath like I do for housing romex wiring?

[lewster]

Originally Posted by KrisE MN

I found chewed wires today so doing the wiring too. I'm used to housing wiring where there's a positive, negative and ground. The wire I'm seeing is just one grouping in strands under a sheath. I've been reading online and watching youtube, but can't find the answer so I'm here... sorry. I'll look further but was hoping someone could help me ... am I looking for a one negative another stranded/positive with a ground inside a sheath like I do for housing romex wiring?

Be careful with your nomenclature. 120VAC marine wire, commonly called 3 conductor, has a black sheath (hot or ungrounded) white sheath (neutral or grounding) and green sheath ( ground or grounded) found inside the outer insulation.

The terms positive and negative are not used when discussing 120 VAC cables......those terms are used for DC circuits.

Go to any boat supply store and you will find 14/3 stranded, 12/3 stranded or 10/3 stranded marine cable readily available. The relative ampacity of these sizes are 15, 20 and 30 amps respectively.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
ABYC Certified Master Marine Electrician
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters
541-490-6357

[D Bishop]

[QUOTE=Tony S;1552862]Hi Folks. I am hoping someone can help. I have added 2, AC 20 amp circuits to my 73 Tradewind. I ran the 12 gauge stranded wire in non metalic flex conduit.

I have received conflicting advice from two different qualified sources I respect. It isn't that they said I was wrong or right but it was a matter of degree in which they favored as the correct way. One felt the stranded was great for the trailer situation (an electrician). The other felt solid was better mostly because AC devices are looking for solid wire.

I am wonder how others feel and would appreciate any input you are willing to provide.

Many Thanks


I happened to carry Colorado Master Lic. # 128 for nearly 40 years so I believe I am qualified to answer. You should certainly use stranded wire in a Mobile installation. Solid tends to become brittle in situations where vibration is possible as in a travel trailer. True in stationary situations solid would be the preferred product but vibration can destroy it over time. Use the stranded in your trailer. The voltage cares not solid or stranded but vibration must be considered in a Trailer.

Don Bishop