The DC House Project

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Zeon

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#220224 1-Aug-2017 13:48

Hey guys,

So bought my first house (in Mt. Wellington, Auckland) - it's a 2 story house with an upstairs 3 bedroom with a downstairs garage/rumpus of the exact same footprint of the upstairs. Works out at around 210m² all up. It also has an out-building of about 20m² with a dedicated in wall BBQ. All this on 1,200m² of land.

It's a pretty hefty mortgage so wanting to convert the downstairs into a 3 bedroom self-contained minor dwelling (retaining the internal staircase but with a locked door) and convert the out-building into a self-contained studio. Have the plans drafted and looking to visit with the council for pre-consent approval with the draughtsman.

The Project - DC House

So we will get a builder and plumber in to do most of that work on those fronts but I have had an interest in a while in doing my own electrics. I have been following solar generation for a while and we have plenty of roof space for panels and can see battery technology is quickly progressing. Considering that lighting is now effectively low voltage DC, gadgets, computers, TVs etc. tend to use it natively all with their own AC/DC inverters and even appliances like fridges or air conditioner units can probably have DC motors installed I think its possible. Cost is a consideration but I know its probably going to be uneconomic considering the extra expense of doing this, even over 20 years of savings from self generated power. I'm more interested in seeing if it can indeed be done and record my experience.

Will also be running AC cabling so can take this step by step e.g. start with lighting only.

I am also unsure at this time if I should get an electrical engineer to consult. I am thinking I will need one but unsure as to which stage this will be needed (and guessing there will be some comments on here).

Stage 1 - Figuring out the basics

What voltage(s) to run. I was originally thinking about running 48v and 12v directly from a distributed point however 12v may be inefficient
- Most lights seems to run off 12v. I want to use lots of LED strips which all seem to run on 12v
- Should keep <50v to allow me to work on myself under the electricity guidelines
- Could run 48v from the central point and distribute to 12v DC-DC converters around the place. Most off-the-shelf cheapies on Aliexpress seem to have limited current support and not high efficiency
- I have not yet looked at the battery tech and what voltages that runs on. If I use 48v maybe that would need to converted up from a low DC voltage on the batteries but have same issues with conversion losses.
- Won't be doing batteries for a while so for the moment will get AC/DC power supplies at central point.

Keen to hear other's thoughts on my ambitions!

Draught floor plan:

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#1834955 1-Aug-2017 13:53

Check this out. It will give you some basic answers to your questions

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=84.22&voltage=48&phase=dc&noofconductor=1&distance=10&distanceunit=meters&amperes=1&x=76&y=22

ubergeeknz

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#1834957 1-Aug-2017 13:54

Doesn't make sense IMO. DC @ 50v is going to need heavy cables, power supplies are going to be more expensive, 50VDC is still fairly dangerous, straying from standards, fire hazard, etc etc

If you decide to go ahead anyway, you would want an electrical engineer to look this over and suitably qualified persons to do the work.

networkn

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#1834959 1-Aug-2017 13:57

Firstly, congratulations on your new house, being a house owner is an exciting time.

Secondly, I think you are going about saving money, the entirely wrong way. As someone else commented, non-standard electrical type stuff is just asking for trouble.

SumnerBoy

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#1835014 1-Aug-2017 14:53

I think this is a great idea personally, and something I would be looking to do if/when I build another house.

I think running LV wiring for all lighting circuits makes a lot of sense. I don't know enough about voltage losses and the finer points to suggest what would be necessary but the idea of having all lighting loads/wall switches being routed back to a central hub, using LV wiring, seems like a no brainer to me.

This allows for extremely cheap and flexible control/dimming/automation of all your lighting. I even had an idea for a type of lighting controller/product which you would purchase with *n* channels and plugin dimmer/automation/??? modules. You would just wire up all your LV switches and loads to the controller and then plug it into your LAN for complete control and setup via a web UI. Never got past the *idea* stage in my head tho...

I for one will be keeping a very close eye on what you end up doing!

Zeon

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#1835027 1-Aug-2017 15:05

networkn:

Firstly, congratulations on your new house, being a house owner is an exciting time.

Secondly, I think you are going about saving money, the entirely wrong way. As someone else commented, non-standard electrical type stuff is just asking for trouble.

To be very clear this is not about saving money - rather to see what is possible technically. I am fully aware and expect this will be a multitude more expensive than a traditional AC system.

Am also completely open to falling back onto AC if it doesn't work out.

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networkn

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#1835030 1-Aug-2017 15:11

Zeon:

networkn:

Firstly, congratulations on your new house, being a house owner is an exciting time.

Secondly, I think you are going about saving money, the entirely wrong way. As someone else commented, non-standard electrical type stuff is just asking for trouble.

To be very clear this is not about saving money - rather to see what is possible technically. I am fully aware and expect this will be a multitude more expensive than a traditional AC system.

Am also completely open to falling back onto AC if it doesn't work out.

I apologise, I misunderstood.

I'd strongly recommend consulting an electrical engineer, is my only advice then, along with my best wishes for your project.

mattwnz

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#1835032 1-Aug-2017 15:13

Is that main house floor plan been redesigned? Just that that lounge looks incredibly small and tight. It is also weird that you have a pool table in that living space that takes up half the room! When you could have a larger kitchen (and with a window) and larger living room. It would almost be better value to build a shed or garage for the pool table if you like pool that much, as you should be able to make far better use of the space in that living area.

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neb

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#1835047 1-Aug-2017 15:33

jimbob79:
Check this out. It will give you some basic answers to your questions

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=84.22&voltage=48&phase=dc&noofconductor=1&distance=10&distanceunit=meters&amperes=1&x=76&y=22

Beat me to it. There's a reason why power transmission is done via HVDC, the losses at low voltage are going to be considerable, so you'll need to feed in rather more than 12V at the source and possibly boost it or use multiple feed points so the voltage at the far end doesn't drop too low. Alternatively, put a UBEC everywhere you need to power things so you get a fixed output voltage from whatever's left by the time it gets to that location. I've got a bunch of 5V-powered stuff that I feed from a 12V outdoors power supply via individual UBECs that take whatever's left at the input and convert it to regulated 5V output, whether the input is 12V or 10V or 8V.

neb

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#1835063 1-Aug-2017 15:44

mattwnz:
Is that main house floor plan been redesigned? Just that that lounge looks incredibly small and tight. It is also weird that you have a pool table in that living space that takes up half the room! When you could have a larger kitchen (and with a window) and larger living room. It would almost be better value to build a shed or garage for the pool table if you like pool that much, as you should be able to make far better use of the space in that living area.

Ah, so I'm not the only one who thinks that. In particular the "lounge" is miniscule, it's only slightly larger than the bathroom, and overall things look really cramped. What you could do is buy a roll of safety marking tape and lay out the plan at full scale (including the furniture) in a field in some local park to get a feel for how restrictive things are going to be. You've also got the kitchen as a chokepoint, the only way to the bathroom is through the kitchen, but the cooking area and I assume where the fridge will go are positioned such that anyone using them will block access through there. The layout just seems like something that would get frustrating quite quickly.

Coil

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#1835069 1-Aug-2017 15:55

ubergeeknz:

Doesn't make sense IMO. DC @ 50v is going to need heavy cables, power supplies are going to be more expensive, 50VDC is still fairly dangerous, straying from standards, fire hazard, etc etc

If you decide to go ahead anyway, you would want an electrical engineer to look this over and suitably qualified persons to do the work.

I am questioning how the DC setup would work more effectively than the current AC standards. Every product is designed for AC power, The parts are cheap and so is cabling. As a residential sparkie all I can think of is the next person. Couldn't one just use an inverter where one is needed?
Given pretty much every DC product takes a different voltage and current how will they be able to power a house full of items? If I get a 12v computer fan and plug it into 48 volts its gonna spin pretty quick or go bang.

What sort of plugs would you use?
Just carry one of these around?

wellygary

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#1835092 1-Aug-2017 16:40

mattwnz:

Is that main house floor plan been redesigned? Just that that lounge looks incredibly small and tight. It is also weird that you have a pool table in that living space that takes up half the room! When you could have a larger kitchen (and with a window) and larger living room. It would almost be better value to build a shed or garage for the pool table if you like pool that much, as you should be able to make far better use of the space in that living area.

The plans appear to be the Ground floor, and as he mentioned he wants to turn it into a self contained rental, (and from the layout - 2 loos, desks in every room, smallish kitchen + pool table) I'm guessing he's aiming at the student "by the room" market

mattwnz

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#1835103 1-Aug-2017 17:01

wellygary:

mattwnz:

Is that main house floor plan been redesigned? Just that that lounge looks incredibly small and tight. It is also weird that you have a pool table in that living space that takes up half the room! When you could have a larger kitchen (and with a window) and larger living room. It would almost be better value to build a shed or garage for the pool table if you like pool that much, as you should be able to make far better use of the space in that living area.

The plans appear to be the Ground floor, and as he mentioned he wants to turn it into a self contained rental, (and from the layout - 2 loos, desks in every room, smallish kitchen + pool table) I'm guessing he's aiming at the student "by the room" market

I guessed that was the case, especially as it has what looks like columns in the space too. Just doesn't look like it will be a very pleasant place to live in the current config. Potentially they could appeal to a better clientele by make it more of a family flat. But maybe their isn't as much coin in doing that.

andrewNZ

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#1835135 1-Aug-2017 18:21

Folly IMO, however.

1) Extra Low Voltage (ELV) is legally, below 50V AC or 120V ripple free DC. Anything over about 50V DC will give you a kick. 110V DC will easily cause you serious mischief.

2) Being a domestic installation, going ELV may not exclude you from the regulations. On the contrary, it may make things harder. To be sure, you'll need to read and understand fully the Electricity Act, the Electrical regulations, and AS/NZS3000.

3) 12V or 24V DC is a lot more common. 99% of industrial control gear is 24V DC. If you're going to do it, stick to these voltages, you'll find it a lot easier to find stuff.

4) Switching ELV with standard mains switches can be troublesome. It takes stuff all to stop the lower voltages, and the higher voltages tend to arc a lot and stuff the switches.

DarthKermit

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#1835137 1-Aug-2017 18:26

AC and DC use very different materials for the electrical contacts in switches. They shouldn't be interchanged.

Zeon

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#1835141 1-Aug-2017 18:31

mattwnz:

Is that main house floor plan been redesigned? Just that that lounge looks incredibly small and tight. It is also weird that you have a pool table in that living space that takes up half the room! When you could have a larger kitchen (and with a window) and larger living room. It would almost be better value to build a shed or garage for the pool table if you like pool that much, as you should be able to make far better use of the space in that living area.

So there are a number of factors in regards to the layout and this was designed by an architect.

Kitchen and bathroom must be where they are otherwise installing a drain will be a huge job.
There are various steel reinforced concrete poles and beams (black squares for columns and dotted lines for beams) <2m around the main living area.
There are virtually no windows with just the doors and the area around the lounge as windows - thought its best to put the lounge near the window
And the house came with the pool table so thought to keep it

Any feedback to the architect is welcome

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