124 replies to this topic

[hanra]

When I say Ill be doing it, Ill be fitting the lights and GPO's etc, my sparky mate will do the switch box etc. Ill suggest that tip for the RCD's to. Im able to keep aircraft in the sky with my Avionics and Electrical engineering qualifications, but Im not allowed to shove 3 wires into a terminal block and tighten 3 screws. Ill be running multiple circuts for the lights. Maybe just a pair for each bay. Not sure where the TX is, Ill have to scope that out. Everyone in our rural suburb is running the same input setup.

[yel327]

That is OK, you are essentially the labourer. They will have to provide you with a CCEW signed to show compliance and also to state they've tested it all. The ban on electrical work outside of electricians is all about correct installation design and testing, not so much about connections. Your sparky mates may have a fault loop impedance tester that you can get them to check the impedance and the fault current of the earth loop - this measures right from you shed through to the transformer star point. AS3000 tells you the maximum impedance for each type/size C/B and fuse. My mrs' parents place was similar to yours, had way too much impedance between the TXF and the house for any of the protection to work correctly. In some cases a fault to earth on a non-rcd circuit would see something like more than 10x the maximum trip time allowed.

[RallyRed]

its all true Brad...all that Yel said.. no need to poo yourself but you do need to be careful to cover your arse legally.

 

Hey Yel....when I did my shed I didnt do the earth current  loop calc. as I just installed a 30ma RCB/MCB combo in the meter box for the shed. My understanding is that this is OK.

This theoretically ( assume Voltage drop calc is good) means you can run a smaller cable.

You know I'm tight.

Edited by RallyRed, 04 April 2016 - 07:39 PM.

[yel327]

its all true Brad...all that Yel said.. no need to poo yourself but you do need to be careful to cover your arse legally.

 

Hey Yel....when I did my shed I didnt do the earth current  loop calc. as I just installed a 30ma RCB/MCB combo in the meter box for the shed. My understanding is that this is OK.

This theoretically ( assume Voltage drop calc is good) means you can run a smaller cable.

You know I'm tight.

 

Yes, the RCD covers the earth fault loop problem. However Voltage drop and Fault loop impedance go hand in hand (as they are both resistance based), so you may be OK or may not be on VD.

[yel327]

 My meter distance is very similar to the OPs, think it was 16mm from memory, 100m to the box from the pole and my sparky 

can't figure how they got away using such small cable over what he said is just over the maximum distance for this size cable.

We have 480 at the box, then its another 50m to the shed and he said there was little to be gained by using any bigger

cable than we had feeding the meter, I'd just have to settle for a little less power at the shed.

Whats your thoughts on this ?

 

Like most house wirers, whomever did it originally doesn't know what they are doing is my guess. Without looking at the installation 16sqmm is not good for 100A in most cases if that is what your service fuses are, regardless of length for a service main (which is normally in underground conduit).

 

Your sparky is not totally correct about no point going bigger. He is talking current carrying capacity, not thinking about voltage drop. Same situation with my next door neighbours house as mentioned before. Your best bet now is to run as big as possible from the house to the shed. Resistance is cumulative, so say you have 2 Ohms over 100m (2 Ohms is just a number picked to make it easy), and 1 Ohm over 50m assuming the same cable size. That is 3 Ohms. If you made the house to shed cable 0.25 Ohms, the total is 2.25 Ohms, not a huge gain though but better. If the cable to the house was 1 Ohm it would be far better as you could use half that cable size from the house to the shed and still only be 2 Ohms total (as the shed is 50m from the house and house is 100m from the supply). So he is sort of right that not a lot to gain in going bigger but you could go bigger on the shed cable for a small gain.

 

What you also have to facto in is in these rough calcs above, we are assuming say 10A at the shed, and the same 10A on the mains cable. But the mains will also have the house load, so it has a compounding affect on voltage drop - the house may have the oven on, HWS on, aircon on etc - there could be 50A on the house, which on the small mains is already creating a large voltage drop. Your 10A at the shed might be a small voltage drop on the shed cable, but it is starting at the house already with a decent drop on it. In the scenario above the house could well be already down to 210V single phase. The fact you have 480V 3ph is a bonus, but at full load this could be down to closer to 420V at the house, and the 480V may not always be there - it depends upon what othe rload is on the TXF - it must be lightly loaded to see you getting 480V.   

 

Best bet is to put a decent sized mains in originally though.
 

[hanra]

Our power on the street is all underground...

[yel327]

There must be a kiosk substation somewhere on the ground or an LV cable going down a pole from overhead LV lines, then overhead LV to a pole top TXF. In most situations you can pick High Voltage lines by 3 x wires, Low Voltage (415V) are normally 4 x wires however either can be two wires and sometimes three for LV (2 phase plus neutral). So if you can find where the cable goes underground at a pole see where it connects to. If it connects to the higher up wires (which will normally be high voltage) and there is 3 wires there must be a TXF located on the ground somewhere. If the cable goes to the lower wires (normally low voltage) or there is 4 of them then it is a low voltage feed straight to your street. 

[yel327]

Great advise.

We do suffer from voltage drop at the house, have checked to see if the house connection is out of phase and it

was all good just low voltage due to cable size. Pole is last on the line shared between to lifestyle properties, the

shed got a sub board in with it's own RCDs, not ideal but it's a lot better than the old extension lead poked through

a length of polypipe that the previous vandals (owners) were making do with.

Thanks for sharing your knowledge, appreciated.

 

The way to fix it is put new sub-mains from the pole to the house. Depending on the way it is installed and the conduit size you might be able to pull it through the existing conduit using the existing cable - I installed a 32mm conduit from the meter box to the shed when I did the block electrics, and about 5 years afterwards I had to run a 16sqmm 2C+E cable through it for a gross infeed solar system on the shed roof (meter box is at the front of the block). That was a 50m run with 2 x 90deg sweep bends and 2 x 45deg sweeps in the conduit. Did it easily and the conduit was empty, you have a ready made draw wire. BUT, if you can't get it through it is dig a trench time! Just depends on the conduit size and hopefully only 2 x 90deg bends. If its 50mm HD conduit you should easily get 4C+E 35mm2 through it. Should also fit through 40mm but you may have to dig down to the bends and cut them off, pull the cable through and put bends back on using conduit joiners where you cut. The work would have to be done by an accredited service provider if the poles are owned by the energy authority. Lots of ASP's around though.
 

[yel327]

That is the problem, project builder screws the eleco, eleco puts in minimum required, house buyer gets crappy final product. Home owner gets stuck with Chinese knock off cable, GPO's, circuit breakers etc. I've seen whole apartment blocks done with knock-off RCD's, I bought one off the plan in Newcastle, plugged in my RCD tester and two of the four RCD's didn't work. Rip off HPM GPO's used etc. Canny builder puts commercial space on the ground floor so no Home Owners Warranty applies.

[RallyRed]

Yes, the RCD covers the earth fault loop problem. However Voltage drop and Fault loop impedance go hand in hand (as they are both resistance based), so you may be OK or may not be on VD.

Doctor said I'm ok with the VD..lol

[yel327]

Stay away from fitters and you'll be OK!

[RallyRed]

Lol

[hanra]

Ok, so some more progress. Don't know where I got the time to build a car.... Now I'm too busy mowing the lawn... Finally got 10 10A GPO's, 1 15A GPO. I fitted 6 double batten fluros in the ceiling and 1 diffused double batten above here I'll build the work bench. I ran an earth wire to the frame at each GPO and fluro. Also fitted a LED flood light at the peak and I still have to fit a sensor light at the PA door.

Got 3 coats of floor paint done. I do prefer the dark charcoal colour like I had in the other shed, but it showed up every little scratch etc. Dragging the trolley jack around left two scratch lines everywhere every time. So decided to go with a lighter colour. Still have to get the Roof Vent mounted to the ridge cap. And come up with some ideas toget my work bench looking how it used to....I'll get there........?

Edited by hanra, 08 May 2016 - 06:47 PM.

[hanra]

And then at some stage I have to sort out the other shed.... I think I'll put the A/C on when I'm doing that!!!

[IMORAL]

I wonder if the car coon is intenitonaly designed to look like a combi van....

Lmao

[AbsynthHatch]

Get some good security Brad and don;t scimp. Camera's, locks, whatever, the best of whats available..

 

You have 2 beautiful cars there and you don't want any scum bag knowing where they live and if your both at work....

 

Get a couple of big not so friendly dogs too.

[hanra]

Shazam

[hanra]

Started on the work bench. Long way to go!! Going to make it into an L shape.

Edited by hanra, 25 May 2016 - 07:54 PM.

[hanra]

Would you believe it... I’m back at this crap job again. Looking at a property to buy which has a 17 x 9 shed. And I just can’t believe it..... no insulation.... has 3 Ridge Vents however. Annnnndddd bloody 28 Solar Panels.... I just don’t know if I want to go through lifting sheets all over again. It was a horrible job the last time I did it.

I found a product called Foilboard. It’s just bloody foam with silver foil either side. I could fit that up and essentially create a ceiling. But it’s $3000 just for the 54 sheets required.... compared to $1500 it would cost for just the same old type of insulation that I used 5 years ago.

I don’t think I can justify spending that money. I’m thinking of trying to hang the insulation up underneath the sheets from the inside???

Gahhhhhh I don’t want to deal with this. Also have to do power points and lights all over again. Who spends $60k on a shed and dosnt fit insulation of install lighting and power points....

[yel327]

If it’s got a concrete floor, get all the materials ready and hire a scissor lift. Will cut your time down massively over ladders doing lights and power off ladders.

Just pay someone to do the insulation. Not worth your life or the hassle

[yel327]

There is a spray on solution too:
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