Friday, May 16, 2014

Electric "almost" Done

Inverter, Breaker Box in close proximity
I am 92% done with the electric after 40 hours of work, completed about two weeks ago.  The system was tested about 9pm the night before I left on a business trip, thanks to my licensed electrician friend (Chris Flath). The test was quite fun:  we plugged a bulb into an outlet while the house connected to shore power ("the grid").  Next, we unplugged AC power.  The light blub went out for about two seconds and then came back on!  Yea! The inverter works!  There is quite a bit more to discuss about this endeavor, but let me assure you to go off grid is not a inexpensive decision...and probably added $2000 to the bill for the PV.  That price does not include solar panels, a charge controller, or any labor. If you paid $50/hour and only used AC, I suspect that 20-25 hours would still be required. Assuming all the basic AC supplies cost about $1000, you should budget at least $2000 for the electrical for labor and supplies.  If you were only wiring for AC, most DIYers could probably handle installation. I had no desire, but I assume others daring individuals are up for the challenge.

Here a list of the key AC & DC components for those of you who are interested:
  • Reliance Controls PB50 50 Amp Generator Power Cord Inlet Box is used to get A/C power into the Tiny House
  • Typical RV A/C Inlet Box
    Magnum MMS1012 1000W Inverter with 50 Amp Charger (bought from but learned that Amazon had a lower price)
  • MAGNUM Battery Monitor Kit and a ME-RC50 Remote Panel allowing me to check the health of the batteries from inside the house
  • Vmaxtanks Vmaxslr125 AGM Deep Cycle 12v 125ah SLA rechargeable Batteries - qty 2.  
  • 300 Amp 12v Dc Circuit Breaker
  • A small breaker box and all the normal stuff -- outlets, switches, gang boxes, #12 Romex, #10 DC wire (from a big box store)
On the tongue, a 'shed' houses the batteries and Propane
So, conceptually, the tiny house has a RV inlet power box that brings in 120V AC power.  That goes into the breaker box.  The breaker box feeds the AC appliances and outlets. AC is also connected to the inverter and which charges the serially wired 12 V batteries.  The three DC 12V fans  run directly off the battery power.  If AC fails or the tiny house goes 'off grid', all outlets and the DC fans will continue, but off battery power. In my design -- in theory -- the batteries will store enough power to live for three days off-grid. I used the load calculator at . My long term plan is to add 2-3 solar panels and a charge controller to keep the batteries fully charged, thus enabling me to be off grid.  The only appliance that will not run off grid is my air conditioner.  (Yes, I have an air conditioner in the loft.)

There are still a few outlets and all the light fixtures are left to install.  Additionally, I have to buy and connect a 12V DC ceiling fan, the propane heater fan, the tank-less water heater, and the range.  What an accomplishment! The whole effort went pretty smooth and went well. The floor plan changed again, however, since the planned location for the range was moved about 10 inches to provide a convenient power location for the range hood.

1 comment:

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