Inverter install success!

[bevans6]

Well, I am a happy puppy!  I did the initial install of my Samlex SA3000K-124 inverter today, long day what with actual day job work and some rain interfering, but the tests worked perfectly and it is up and running!  I did a very simple install to prove in the concept, it is running directly from the bus batteries and alternator feed, and is feeding just the 15Kbtu rooftop AC unit via an Iota auto transfer switch.  I have shore power coming into the first Iota transfer switch as prime, generator as secondary, the output of that switch feeds to the main house loads and feeds the second Iota switch as primary, while the inverter output is wired into secondary.  The output of that switch feeds a pony panel with input and output breakers and finally to the AC unit.  All the grounds are bonded back to chassis, all the neutrals are switched back to which ever load is feeding at the time and bonded at source only.

The inverter starts the AC compressor effortlessly, so that worry is finally put to bed.  With the house batteries only, input voltage is 24 volts running the AC on high, with the bus at idle the alternator is putting out 26 volts, with the bus at high idle the alternator is putting out it's normal 27.5 volts, showing 28 volts on the remote control display of the inverter.  The inverter load display shows 40% load when the AC is on high.  So I think all is well.

Next steps will be to add two more house batteries and develop a switching system so that the alternator can charge them, the inverter can run off them at stops, or run off the alternator on the road, and hook up some more of the house circuits so I can use it to watch TV, microwave, that sort of thing.  I need some more parts to do that, one step at a time!  No pic's till I dress the wiring more better   

Brian

[John316]

Congrats, Brian. That is a great accomplishment. Good for you.

And the important part is it works.

God bless,

John

[Joe Camper]

On many inverters anything that you power from it will loose power if you have certain types of inverter failures, and that would be during the times when the bus has generator or shore power coming in.

This could be a problem if for example you have a residential fridge and it is built in and you can not access the plug without pulling the fridge out?

How would you power your fridge in the event of an inverter failure?

Easy solution, Interupt the a/c feeds both in and out of the inverter with twist lock plug ends and flip flop them. In the event of an inverter failure you can then easily unplug the a/c in and out of that inverter and then plug them into each other effectively bypassing it and suppling power directly to those circuts without going thru the inverter.

Only drawback is you will also loose that charger so either you need a small backup charger or the other inverter picks up the charging duties.

I know you got to be excited, one more piece of the puzzle.

[bevans6]

The cascaded Iota automatic transfer switches, while on the one hand inelegant, handle that sort of thing automatically.  The power output of the inverter is the lowest priority, the generator is second while shore power is highest.  If there is either shore power available or the generator is running, they provide power to everything.  If neither is available but the inverter is turned on, only then will it be selected  through the Iota's.  We put about 6 hours on it this weekend, we are currently about 20 miles east of Port Huron in MI sitting in a rather nice KOA (I know many don't them, but we seem to have good luck or low expectations, I'm not sure which) and the whole thing worked a treat, cooled us down on the road no problems.

Right now only the AC is connected to the inverter.  Over time I expect to add more circuits, and add battery capacity so that it can run things off shore power for longer.  Right now it is only connected to the bus start batteries, the only 24v pair I have right now.  I have built a space to support around 500 AH at 24 volts in 6 volt golf cart batteries, and have to add a charger suitable for that lot, plus a solenoid to let me charge them from the bus alt. while driving.  lots more to do, but this step was so far a total success!  Very impressed with the Samlex pure sine inverter so far.

Brian

[Sean]

Easy solution, Interupt the a/c feeds both in and out of the inverter with twist lock plug ends and flip flop them.

Not legal, sorry.

Inverters need to be hard-wired, or else only power an immediately adjacent appliance.  The only place an electrical panel can be fed by a cord-and-plug arrangement is at the main shore power input.

You could implement such a transfer mechanism with mechanical switches, relays, or contactors, though.

-Sean
http://OurOdyssey.BlogSpot.com

[Joe Camper]

O/K Sean point well taken.

This was not my design but converter configured and it does work as designed and I thought, a clever solution.

When you say "not legal" could you expound on that some?

They could be very easily removed from the loop but I use them.

I only have 1 2500w inverter and everything on the camper short of the heaters and a/c powered thru it.

When we get to a campground I by-pass it allowing us to more freely use the camper without managing loads, the inverter only carries a 25amp breaker.

[Sean]

When you say "not legal" could you expound on that some?

Sure.

The National Electrical Code, which has been adopted into law in all states, establishes the requirements for all wiring above 30 volts in an RV.  The section of the code that specifically applies to RVs is 551, however many other parts of the code are also applicable and incorporated into 551 by reference.

The only "wiring methods" permitted in an RV are those specified in code articles 320, 322, 330-340, 342-362, 386, and 388 (per 551.47a), and those do not include flexible cords with attachment plugs.  Even if flexible cord was allowed, article 400.7 does not permit this use for an attachment plug.

There is one very limited exception, spelled out in 551.47p1, for "expandable units" (slide rooms), which allows the wiring system in a slide room to be connected back to the main coach by a flexible cord and plug and makes it specifically allowable under 400.7, with a whole list of requirements to be met.  Note that, in general, slide room manufacturers have chosen not to use plugs and instead follow the hard-wire guidelines for slide rooms spelled out in 551.47p2.

All of that is a long-winded way of saying that you can not have a receptacle and a plug in the middle of a wiring system.  You can (and, in fact, must) have a plug on a shore cord, and you can connect individual appliances to receptacles by means of a plug and cord, but that's it.  So, for example, if you had a small inverter just to run the fridge, and it was mounted close to the fridge, then the fridge could just be plugged into a built-in receptacle on the inverter.

The code also requires inverters permanently installed in RVs to be "listed" for that purpose, and most listed inverters over a few hundred watts will have hard-wire provisions for exactly this reason.

Pretty much the only other place you can use a cord-and-plug connection is for the generator; the code permits a receptacle fed from the generator to supply the standard shore cord (551.30).

When we get to a campground I by-pass it allowing us to more freely use the camper without managing loads, the inverter only carries a 25amp breaker.

There are several code-compliant ways of achieving this; one is to use a simple automatic transfer switch, activated by shore power, to switch the loads from the inverter to direct input.  Most large RV inverters actually have such a switch built-in, bypassing the inverter when shore power is available.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com