Need WA State electrical contractor/off grid advice

[Blitzkrieg]

Simple question.. we are soon to build a home which will eventually have off grid systems. Can we wire the lights/fans/12VDC wall power outlets and meet code, using a 110 to12VDC inverter at the box and 12VDC wiring to those ?

The plan is later to tag the 12VDC off grid generation units into a battery bank to supply that wiring. I know it also needs a controller. The home will also have 110 and 220 outlets and of course other for appliances, etc. This will be in Mason Cty

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[3MTA3]

Sounds interesting - how are you planning to charge the batteries? I figure at some point in our transition to a third world country that many of us will go off grid as a result. I'm planning on a natural gas standby system for when utilities become less reliable, but low key under the radar off grid is a better solution.

 

[Stomper]

I'm a bit confused by your terminology.

1.
An "inverter" converts DC to AC, while "rectifier" converts AC to DC via the magic of diodes.


2.
Having 12vdc outlets in the house? IMHO you would be better off just conventionally wiring your house from the outlets/wall switches back to the service panel, then between the service panel and service meter have a transfer switch that could:

A.
Auto/Manually swap to a generator back-up

and/or

B.
Auto/manually swap to an inverted battery bank.


A couple challenges that I can think of straight away is:

1.
Practical domestic appliances in North America are generally designed for 100-120/200-240vac, and small DC appliances (computers, radios, cell phones, clocks, Bluetooth, etc) already have a 120-240vac to DC rectifier in whatever voltage they require (ie 2-14vdc)... That's what the "brick" is on their power cords, either in-line or on the end you plug into the wall outlet.


2.
The wiring requirements for AC & DC are different.


Although I have a (limited) OR license, I'm not aware of any restrictions that says you can't run DC rated wiring in a residence so long as it's permanently labeled and used with an outlet interface that prevents an accidental use of 120/240vac appliance. You can also trickle charge your battery bank with a floating charging system from the grid so it's always topped off and ready to rock, then use solar to charge when off the grid.



Hope that helps!

 

[Blitzkrieg]

Stomper.. yes it will be a single large rectifier so as to allow simple 12VDC LED lighting fixtures with very low power drain when we go to the off grid system, which will be added later on with cash purchases of equipment

The large appliances will run on 110/220 and there will also be standard outlet 110/220 plugs. BUT there are plenty of small 12 VDC RV type appliances like coffee makers and such that can run off 12VDC outlets

What I am hoping to do is simply the (later) addition of a 12 VDC power system to the 12 VDC side of the rectifier without having to add an inverter system and (maybe) the switch box. Does that make sense to you? I've been advised that starting on grid and slowly adding off grid generation systems is the best way to go

The 12 volt generation will (eventually) be solar/wind/hydro and a backup diesel generator, powering the battery bank

 

[Blitzkrieg]

To encapsulate, I am hoping to eventually have an off grid system with minimal energy losses to an inverter by directly supplying power on the 12VDC side of the rectifier with additional breakers, of course. My gal tells me WA State code is the most strict in the country and I'm wondering if it will meet code, using RV type lights and outlet plugs

 

[Stomper]

Sounds like a fun project, and you most likely can "legally" do such a thing as long as it's permanently labeled at each receptacle and use specific receptacles that prevent the crossing over of 12vdc and 110/240vac systems/appliances.

It may blow the mind of the electrical inspector!

 

[Blitzkrieg]

That my friend is where the rubber meets the road!

 

[Ligito]

Sounds like a fun project, and you most likely can "legally" do such a thing as long as it's permanently labeled at each receptacle and use specific receptacles that prevent the crossing over of 12vdc and 110/240vac systems/appliances.

It may blow the mind of the electrical inspector!

Then, ask for an inspector that knows what he is doing.
In Multnomah County, inspectors are cross craft inspectors, not specializing, so all of them do not have all of the skills, necessarily.

 

[Blitzkrieg]

Ligito, how would we go about that? I fear Mason Cty is shall we say, a bit backward?

 

[Gunwheeler]

Electrical Inspections in Wa are conducted by the Dept Of Labor and Industries. The National Electrical Code (NEC) applies. Also the state has what is known as the WAC which covers what the state feels the NEC does not. You can review the NEC to determine what will be required. Expect to see the state require everything required for a normal residential installation. The NEC applies whether you are on "Grid" or off.

My home has 5.2 KW of panels and is a "Grid tie" system. I chose to stay away from batteries. Power bills are next to nothing ($6.80) a month. Thru the state incentive system I get a check from the power company yearly ranging between $1200 to 1800. I have a generator for backup and the major appliances are propane. The home has normal insulation levels but gains heat via its exposure. This is my second solar home. The first was in the Enumclaw area ( we now are in the mountains near Yakima). I lived in it over 25 years. The comfort level exceeded a normal home. The cost of living in it was very low compared to similar sized homes. I think if someone were to build there own home they should take every advantage to save energy they can. The start up cost can be expensive but returns are better than most investments.

 

[mjbskwim]

Personally,I would run the wiring after the inspection cause the 12v isn't much of a problem.Don't even bring it up with the inspector. yes,especially a Mason co inspector.
You will be inspected before the sheetrock,no? If after,run some conduit for the 12v.

So Stomper or RVTech,how far can he stretch the power of 12v across his house,without losing too much power? I mean a semi runs lights at 50',so I guess that would work fine

 

[Father of four]

Is it not great to have them tell you what you can and can not do with your property?

What a shame!!!!!!!! You think the founding fathers would agree that our land, our private property, should be handled this way?

Year after year people that you do not know and has never stepped foot on your land come up with more and more rules and regulations. That totally goes against your personal rights and freedoms. When are we going to stand up and stop letting other people tell us how to use our on stuff. If it doesn't hurt anyone then leave us alone.

What a racket the housing industry has become.

 

[Father of four]

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Even better.... <broken link removed>

 

[Father of four]

40,000 new laws take effect in 2014 ? The Lead with Jake Tapper - CNN.com Blogs

 

[Blitzkrieg]

Electrical Inspections in Wa are conducted by the Dept Of Labor and Industries. The National Electrical Code (NEC) applies. Also the state has what is known as the WAC which covers what the state feels the NEC does not. You can review the NEC to determine what will be required. Expect to see the state require everything required for a normal residential installation. The NEC applies whether you are on "Grid" or off.

My home has 5.2 KW of panels and is a "Grid tie" system. I chose to stay away from batteries. Power bills are next to nothing ($6.80) a month. Thru the state incentive system I get a check from the power company yearly ranging between $1200 to 1800. I have a generator for backup and the major appliances are propane. The home has normal insulation levels but gains heat via its exposure. This is my second solar home. The first was in the Enumclaw area ( we now are in the mountains near Yakima). I lived in it over 25 years. The comfort level exceeded a normal home. The cost of living in it was very low compared to similar sized homes. I think if someone were to build there own home they should take every advantage to save energy they can. The start up cost can be expensive but returns are better than most investments.

Unfortunately our backwards PUD will only let us use excess power to pay off the bill and no more, we already looked into it, so a battery bank may make more sense for us with less generator/wind/hydro wear and tear

 

[Blitzkrieg]

Personally,I would run the wiring after the inspection cause the 12v isn't much of a problem.Don't even bring it up with the inspector. yes,especially a Mason co inspector.
You will be inspected before the sheetrock,no? If after,run some conduit for the 12v.

So Stomper or RVTech,how far can he stretch the power of 12v across his house,without losing too much power? I mean a semi runs lights at 50',so I guess that would work fine

May have to do that. If the wire GA is sufficient I don't think there will be too much power loss. Unfortunately the entire exterior will be ICF material, not sure how easy it will be to wire that myself after the fact, must do research. Thing is I don't want to waste money on 110 wiring and fixtures when they won't get any use after the off grid comes into play.

Still hoping to hear from a WA State Electrical contractor or off grid expert ... if one is reading this, please set me on the right path

 

[sailorfej]

Hi Blitz,

Mixed electrical systems like this are very common on boats, particularly private yachts. I used to install them myself all the time. So might want to inquire around shipyards for folks experience with those types of installations. That being said, back when I was doing that kind of work, most marine electricians were not officially licensed electricians so it may take some work to find a marine electrician also licensed for residential work.

 

[solv3nt]

A couple of things to consider:
1) The NEC allows for two types of connections to your main panel, line side (utility connection) and a backfed circuit breaker. The backfed circuit breaker is limited by the amount that it can supply.
NEC 2011 - 705.12.D.2 Bus or Conductor Rating
The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor
Exception:
Where the photovoltaic system has an energy storage device to allow stand-alone operation of loads, the value used int he calculation of bus or conductor loading shall be 125 percent of the rated utility-interactive current from the inverter instead of rating of the overcurrent device between the inverter and the bus or conductor.

In your case, you'll have a main panel, let's say 200A service, the main breaker to your house is rated at 200A, so if your panel is only rated for 200A, then you are limited to 200A*1.2%=40A supply. You will be limited to approximately 7kW when you factor your 125% conductor rating.

2) Consider voltage drop, for a 15A 12v circuit, you have a max of 15A before you trip your breaker. Let's say that you have a 50' run, and power 4x 12VA lights (one room). Your total lighting is 48VA, or 4A at 12V. 12ga copper conductor has a resistance of 1.93ohms/1000ft. You will lose 2.3v to make a 50' run to your lighting. You will need to upsize all of your conductors to at least a 10ga, possibly even 8ga wire. Most lights barely accept 12ga wire, let alone 10ga or 12ga.

VA = V * A
Vdrop = V * R/kft * kft

IMHO, I would run everything on 120VAC, and use an inverter at each piece of equipment to convert your 120VAC to 12VDC.

 

[solv3nt]

Hi Blitz,

Mixed electrical systems like this are very common on boats, particularly private yachts. I used to install them myself all the time. So might want to inquire around shipyards for folks experience with those types of installations. That being said, back when I was doing that kind of work, most marine electricians were not officially licensed electricians so it may take some work to find a marine electrician also licensed for residential work.

Did you work at Christensens?

 

[Blitzkrieg]

solvent, I got all of that except the 110 and an inverter at each piece.. do you also mean lights and 12VDC outlets? How can I power them with an off grid system, directly? I just don't get how I can use off grid 12VDC generation that way without independent 12VDC wiring to each light, etc?