Small AC motors and Inverters

"Just thinking of some sort of permanent 110V wiring connection to the inverter might be nice. Rather than running the trailer's power cord up to the front each time"

You can run a 15a extension cord (light weight) back instead of hauling the (heavy) shore cord forward :)

Hi,

While a relay will work, since I have to unplug from shore power, and my default for the converter is disconnected, it seems to me to add a failure point. Contacts do eventually degrade. It is easy and simple to add an inverter powered outlet in the shore power cord storage box. I have shortened the OEM cord in an appropriate manner so there is no risk of heating from the wire being coiled.

One of the design features of my magnum inverter is a transfer switch rated at 60 amps--and this is for a 30 amp service.

That PD transfer switch will work perfectly.

I understand the some RVs auto switch from the inverter to shore power when it's available using something like this DPDT relay:
Amazon Relay

Anybody installed one of these?
It's rated for 30A 110V as is the trailer's shore power connection.

Progressive Dynamics makes one with a time delay circuit which I don't need:
Progressive Dynamics


Just thinking of some sort of permanent 110V wiring connection to the inverter might be nice. Rather than running the trailer's power cord up to the front each time.

smkettner wrote:
NEC does not allow doubling of the conductors. Just get the right wire size for the job.
And RVIA standards follow NEC.

where the heck did you get that ?

wiring DC input power to an inverter is NOT
120vac outlet wiring, or power pole service drop to house, or 120/240 appliance wiring

I read class 2 & 3 are less than 100VA signal type circuits such as a thermostat control. This is a power feed to a 1000w inverter.

http://ecmweb.com/site-files/ecmweb.com/files/archive/ecmweb.com/images/archive/0201commcode.pdf

Yes that picture is a typical disaster. No need to continue the madness.

Thanks GD.. i was living in blissful ignorance even after i found out 1/2 the DC lines are reversed in MY camper. ;/

smkettner wrote:
NEC does not allow doubling of the conductors. Just get the right wire size for the job.
And RVIA standards follow NEC.

They are talking about 12V (TWELVE VOLTS) wiring, this typically falls UNDER 30V AS CLASS TWO wiring.

NEC class 2 wiring does not require splices or connections in junction boxes nor does it require any class two junctions to be visible (in other words junctions can be hid in a wall).

Doubling conductors is addressed in CLASS 1 wiring (which 12V is not).

RVIA "standards" only follows NEC for 120V (ONE HUNDRED TWENTY VOLT) wiring..

For 12V wiring pretty much anything goes including HIDDEN junctions behind paneling..

If you want to get an eye opening experience I would suggest that you remove some of the paneling in your RV.. Once you see how shoddy RVIA wiring is for 12V you will be scared to ever sleep in it again!

Just as an example you can view what I found in my RV..



If you zoom in you will see a bundle of 12V and 120V wiring that is melted together and had even charred some of the paneling..

The wire was so tight that it had chaffed on the metal sleeves in the wall studs (those sleeves are to protect the wire from staples, nails, screws but darn near burnt the trailer down.

You will also notice a bundle of 12V wiring all connected via one huge wire nut hidden behind the paneling.. That was the 12V ground, every 12V circuit came to that junction and was spliced with a single #8 ground wire.. That #8 wire was UNDERSIZED for all the 12V circuits that it served!

SMK,

I beg to differ. I'm going from memory here, but I believe that paralleling of conductors (ie 2 100a to feed a 200a service) IS allowed. The conductor types must be of same physical characteristics.

The stipulation that I remember is that the GROUND must be able to handle the full amperage load, but there were exceptions to this in residential applications.

Again, I'm going from memory here :P

smkettner wrote:
NEC does not allow doubling of the conductors. Just get the right wire size for the job.
And RVIA standards follow NEC.

Who cares about RVIA and NEC? Not me, and not the OP :) However good advice is always valuable whether from them or anybody else, such as the good folks on this forum.

On doubling wires to get lower R on that path, The forum here told me a while back that it works, but to be sure that the thinner wire could still handle the whole current if the fatter wire broke off somehow. And of course that the fatter wire could take it all too if need be.

ISTR the identical wire thing was for 120v where phasing matters and it is near impossible to achieve, but with DC wires that is not a problem.

My 2000w Vector inverter (which has two pos and two neg terminals) has a wire kit that is two each of 3 feet #4. The ring lugs on those are marked "200A" But the actual inverter manual specifies a single length of 1/0 up to 6 feet and 3/0 to 10 ft. Cobra inverters have a similar arrangement.

I guess Vector and Cobra are still in hiding from the NEC! :)

If I had a PD converter, which has a second set of terminals too, I would be tempted to double them up on the same battery bank instead of to a second battery bank as was likely intended.