12v or 220v

[Brainless]

I am in the planning stages of building a house constructed of 2 40ft sea containers. As these are completely made of corton steel i was wondering if electrical wiring can be 12v using the metal construction as a ground, just as in a car. Using copper or alluminium hollow tubes for distributing the electricity.

As everything is still in the planning stage i could plan to buy as much appliances that directly uses 12v DC instead of converting it to 220v first. Obviously some appliances will be very hard to get and for those i would like to have a small converter with enough power for that particular appliance.

Cooking will be done with butane/propane. i guess a microwave will be a challenge using a whopping 60A at 12v.

An airconditioning using ice water and heat exchanger will be used at night to make sleeping comfortable. Where i live the climate is tropical.

It will be completely of grid, but before making the necessary calculations on how much solar (and wind) power i will be needing depends on if this wiring for 12v is doable.

[Sunking]

Well let's put it this way:

Direct Current flowing through dissimilar metals = Corrosion. Sounds like a sinking ship to me. Add water and you accelerate the process. Add salt water to the equation and you have a rust bucket in no time at all....

Need to know more?

You should never use a frame or ground reference as a current carrying conductor regardless if AC or DC for low voltage systems under say 1000 volts.

[Mike90250]

Don't use chassis as a conductor.

Also, if the containers are going underground, I've heard the roof center can't take a lot of load, only the corners.

Where do you get ice water ?

[Mike90250]

Voltage drop is your other big problem, at 220V, you can run wire all day long. But at 12v you will find that 4% drop is going to be a big factor and cause lights to be dim.

http://www.csgnetwork.com/voltagedropcalc.html

try plugging some numbers in there, and see what your losses and wire gauge will be.

perhaps a inverter can be bought for the savings in wire !

[Brainless]

Wow

Thanks for the fast replies.

I got my "inspiration" because i traveled/lived many years in a to a camper converted bus (about 10m long). Everything inside was 12v. Work very good, with a 12v fridge with propane backup.

I am curious to know why corrosion is the main problem. Would that only be because high currents? (i just like to know things. )

The container will be placed on pillars about 150 cm high, ensuring enough air flow under the floor and to be safe from flooding that happens about once in a decade. The roof will be a flat roof placed about 30cm above the container roof to ensure air flow preventing still standing water on the roof. It will have eaves extending about 1 meter beyond the walls to shade the windows and walls from direct sunlight. It will facilitate mounting solar panels for electricity and hot water. Also the containers will be complete insulated with foam inside and outside.

The icewater that will be pumped around through a heat exchanger is only viable when there is a good source of cheap ice. In Thailand ice factories are everywhere and for a about 10-20 baht (about 35-75 cents US$) worth of ice, depending on season, you can cool a good insulated bedroom for a whole night.

I am not commited to anything, so i welcome information that keeps me from making a wrong turn.

[Sunking]

I am curious to know why corrosion is the main problem. Would that only be because high currents?

Higher currents do have something to do with it, but mainly DC. Any electro-plating process involves passing DC current through different anodes and cathodes (dissimilar metals). Use the right materials or combination (metals) and it is a good thing like galvanized steel plating with zinc to steel.

Mix copper with aluminum, or copper to steel and you get green, blue, or red rusty crusty goop that feeds on itself with addition of oxygen, moisture, and salts.

[Brainless]

Mix copper with aluminum, or copper to steel and you get green, blue, or red rusty crusty goop that feeds on itself with addition of oxygen, moisture, and salts.

I understand now that you mean galvanic corrosion. Would you not need an electrolyte for that to occur? If both anode and cathode are isolated from eachother and not even in contact through the air would corrosion still occur?

[Brainless]

Voltage drop is your other big problem, at 220V, you can run wire all day long. But at 12v you will find that 4% drop is going to be a big factor and cause lights to be dim.

http://www.csgnetwork.com/voltagedropcalc.html

try plugging some numbers in there, and see what your losses and wire gauge will be.

perhaps a inverter can be bought for the savings in wire !

I was thinking of using aluminum as a kind of power rail. I have seen those used in custom build rack computers. Although in that case the lengths were relatively short, about 2 meters max. The amps however where between 50amps for the 12v and 100 amps for the 5v rails. Some stress tests made the aluminum tubes whistle like a church organ pipe. Those where definitely not big enough. I was the computer guy, not the electrical guy but was there to configure the software of the whole setup.

A length of aluminum is around 2-4 US$ per meter depending on diameter and wall thickness. I estimated the total cost for the power rails to be somewhere around 100-200US$. As the aluminum tubes are hollow there is a lot of surface area and convective airflow to help keep it cool. The longer distances would only power a few 10-20w led lights. The voltage drop on a big enough diameter would be around 1-2%.

[mountain]

Assuming Bangkok Thailand to be a civilized major world city, I would assume that your government has some form of electrical safety authority. Also I assume Thailand has some sort of regulatory system concerning building permits, fire code and electrical permits.
Even if your planned home is not connected to a public electrical utility, you are still bound by your local electrical code.

Building an unconventional home (I did it) is gratifying... and the end result can be a fine home that uses far less energy than typical. However you must be 100% aware of the local law regarding fire, building & electrical standards (ignorance is no excuse). These laws are designed so that your self-built dwelling represents no unnecessary hazard to the community, or people (including emergency services).

Building outside the law is often possible in rural areas. But the financial wisdom of building a radically unconventional dwelling, without a building permit, or an electrical permit, is questionable. You may render your property un-mortgageable & un-insurable (= worthless) should you ever want to sell it in the future.

[Sunking]

If both anode and cathode are isolated from each other and not even in contact through the air would corrosion still occur?

Well them you would not have electrical contact. There are devices that allow for either aluminum or copper conductors to be used that are safe now days. But they are special and require preparation and anti-oxidant compounds to be used.

But that is neither here or there. Running DC current through a building framework is not only bad on the electrical system but all systems in the structure like plumbing and structural steel.

Take my advice, do not do it.

[russ]

Galvanic corrosion is a major concern with equipment like pipelines. It is a bit difficult to understand (as in damn near impossible) and protection systems sometimes seem to run in the realm of magic.

Low current can be a big problem - that much I am very sure of.

[Brainless]

Assuming Bangkok Thailand to be a civilized major world city, I would assume that your government has some form of electrical safety authority. Also I assume Thailand has some sort of regulatory system concerning building permits, fire code and electrical permits.
Even if your planned home is not connected to a public electrical utility, you are still bound by your local electrical code.

I am not a Thai national but i do know that it is quite easy even for an amateur to build a house which is of better standards than a typical Thai house.
In this case no building permits are necessary because the house will be mobile. Different category, and actually the only way a foreigner can really own his own 'house'. Land ownership is forbidden, only rent is possible. As the rental contracts are often only three years, conditions can change. If you build on the land you will loose it, with a mobile house it's just putting it on a trailer and move it somewhere else.

Building an unconventional home (I did it) is gratifying... and the end result can be a fine home that uses far less energy than typical. However you must be 100% aware of the local law regarding fire, building & electrical standards (ignorance is no excuse).

Laws are quit different as in our western countries. You will be schocked (pun intented) when you see how electricity is installed here. I am sure i can do a better job by getting to know what can and can not be done and checking up on a installer.

These laws are designed so that your self-built dwelling represents no unnecessary hazard to the community, or people (including emergency services).
Building outside the law is often possible in rural areas. But the financial wisdom of building a radically unconventional dwelling, without a building permit, or an electrical permit, is questionable. You may render your property un-mortgageable & un-insurable (= worthless) should you ever want to sell it in the future.

What mortgage? Which insurance?
The only criteria i follow is that it has to be save for a family to live in. That includes safety as much as possible from fire, storm, flood even burglary (not really that common here but a safe room nevertheless)
Installation of electronics will be done by a certified electrician from a western country, i have seen to much sloppy work done by the local 'experts'. Sure they are there but why take a risk. I know my own limitations. And i know where my gaps in knowledge are. That is one of the reasons i asked here and from others. If something can't be done i would like to know why because in my experience for many people anything slightly out of their own experience can not be done.

[Brainless]

Well them you would not have electrical contact. There are devices that allow for either aluminum or copper conductors to be used that are safe now days. But they are special and require preparation and anti-oxidant compounds to be used.

But that is neither here or there. Running DC current through a building framework is not only bad on the electrical system but all systems in the structure like plumbing and structural steel.

Take my advice, do not do it.

You advice is taken. Would another way of distributing 12v be available. I like the idea of a rail but common wire/cable is not a problem.
Would distributing 12v through 2 separate rails made from the same material pose problems. I know in newer apartments the mains is distributed through aluminum cables instead of copper. But once in the apartment itself it is all copper. Does that have a particular reason, or is it just easy availability of copper?
I know the problem of needing larger amperages when using lower voltages and voltage drops?
If i sum up the needed power through 12v then it is this:
distance power needed
40ft 30w
35ft 15w
30ft 15w
25ft 150w (inverted to 220)
20ft 15w
15ft 30w
10ft 15w
05ft 15w
total 285w
This will probably be on all at night at the same time because they are lights and a tv/or computer. Daytime probably only a computer (150w=screen+minipc).
How would i wire that best?

[Sunking]

Brainless 12 volts is challenging or I should say can get expensive to distribute over distance with larger sized loads. The problem is low voltage itself, requires higher current and associated voltage loss. The way to compensate for the loss is with larger conductors, and that can get expensive.

So I think by now you can see what I am driving at 220 VAC is IMO the better route. 12 volts is fine for the low power stuff say 20 to 30 watts or less, but at 220 you can use 14 and 12 AWG for just about everything except for things like Air Conditioning or electric ovens to name a few.

[SpaceOddacy]

Well let's put it this way:

Direct Current flowing through dissimilar metals = Corrosion. Sounds like a sinking ship to me. Add water and you accelerate the process. Add salt water to the equation and you have a rust bucket in no time at all....

Need to know more?

You should never use a frame or ground reference as a current carrying conductor regardless if AC or DC for low voltage systems under say 1000 volts.

So, is that why cars rust so fast *eluding environmental conditions*