30 amp generator with 12 gauge wire?????

Chris is correct. Onan and many other equipment manufacturer use Machine tool wire which has higher current carrying ability.
You must have some way of separating the shore power and genset systems. It is either a transfer switch or receptacle. Who installed the genset?

That is 105c wire, plenty big enough, rated just fine for the load.

Also depends on the wire insulation rating. IIRC Typical romex is 60° while THNN is 90° or 105° and can carry a bit more.

14 million Onans out there built the same way w/o 1 problem, and you're questioning it ? Not smart !

its NOT alu
its "tinned" copper, meaning plated to stop corrosion

Just noticed, and hate to muddy the waters even more, this isn't copper stranded wire. It's silver. I don't think it's aluminum, but what else do they use for conductors?? Would this give it a higher amp rating? I can post the stamping on the wire if it would help, but the stamping is about 6 inches long. Says at the beginning 12 AWG, but has all kinds of numbers after that, including lots of voltage numbers, up to 1000 volts. No amperage rating given, because that is dependent on length of run.

This is all confusing. I'm about ready to just trust Onan to do it right, put it back in and hope it doesn't burn anything down, lol.

Good to know. I guess the switch is built into the converter. I'm honestly not too worried about that. Once the wire transitions to 10 ga, i'm comfortable with everything being ok after that. I'm just worried about the 12 ga wire. I know it's a short run, and that it is what was supplied from Onan, but it's still awful concerning when we boondock. I sure don't want to stress every time the air conditioner is on and someone starts the microwave. I want to be sure it trips the breaker before melting wiring.

It's also aggravating. It would have cost Onan a few extra cents to run 10 ga and not have to worry about safety instead of using the absolute bare minimum. These Onans go for big bucks, we should be paying for quality, not the least that "should" do the job.

rmoore0852 wrote:
Sorry, been watching a movie. Lots to reply to. By AC I did mean AC current, not air conditioner. No real transfer switch on my rig, unless it is built into the converter. The 12 ga stranded wire is factory wiring from Onan. The inside of the genset has never been messed with, trust me these are the factory supplied wires. They run about 6' out of the genset and into the front storage compartment. Inside this compartment is a junction box, where it transitions to solid core 10/3 wiring. This wire runs back to the converter where it powers the entire panel just like the shore power does.

Everything else on this rig that was installed by the dealer was butchered, including using spare trailer light wiring to hook up the control switch for the genny. Where the 12 ga wire hooks into the generator is deep inside the panel and still has the nice, neat factory wiring looms on everything. I have no doubt that the 12 ga wire is what came from Onan, but curious about using it on what I thought had to be 10 ga all the way through. Maybe it is such a short run that 12 ga is OK. I may rewire with 10, but in order to hook up the hot wire it will require some moderate disassembly of the front of the genny. That connection isn't easy to get to.

If you don't have to plug the shore power cord into the generator then you have an automatic transfer switch. Usually the GEN is the primary, ie when the generator is started it supplies the AC and the shore power is dropped out.

And as others have said, for 6 feet I wouldn't worry about it. However, if you have the gen out, the cost of 6' of number 10 wouldn't hurt. I'd do it if it were mine.

Sorry, been watching a movie. Lots to reply to. By AC I did mean AC current, not air conditioner. No real transfer switch on my rig, unless it is built into the converter. The 12 ga stranded wire is factory wiring from Onan. The inside of the genset has never been messed with, trust me these are the factory supplied wires. They run about 6' out of the genset and into the front storage compartment. Inside this compartment is a junction box, where it transitions to solid core 10/3 wiring. This wire runs back to the converter where it powers the entire panel just like the shore power does.

Everything else on this rig that was installed by the dealer was butchered, including using spare trailer light wiring to hook up the control switch for the genny. Where the 12 ga wire hooks into the generator is deep inside the panel and still has the nice, neat factory wiring looms on everything. I have no doubt that the 12 ga wire is what came from Onan, but curious about using it on what I thought had to be 10 ga all the way through. Maybe it is such a short run that 12 ga is OK. I may rewire with 10, but in order to hook up the hot wire it will require some moderate disassembly of the front of the genny. That connection isn't easy to get to.

Within the component, such as genset, not for wiring in the rig. Wiring with in the rig must comply with NEC 551.
Wiring from genset should go to junction box where it connects to the rig's wiring system. Normally #10 Type NM that goes to transfer switch or genset receptacle for shore power.