trade test practise - consumer unit bus bars
 

sparkis, here is a little question regarding consumer units:

two ways I used it in the trade test, and two complains of the tester.
1) red 9 on the picture, bus bar connects all breakers from underneath. Is this common/acceptable for Australia, or do we have to connect the power from the top into the breaker?
Tester said, in Australia only from the top, because main conductor comes from the roof, from above.

2) red 8, that’s the terminal bar for RCDs as I recognized it, and I used it for that.
The tester didn't know about a third bar, and let me connect to the neutral bar



http://blog.sparksdirect.co.uk/image...mer-unit-1.jpg

Re: trade test practise - consumer unit bus bars
 

Hello All,

Mains goes to your meters first so it really doesn't matter if they come in from the roof, when i did my test all power was supplied from the bottom and all the feeds taken from the top.

Regards
Kevin

Re: trade test practise - consumer unit bus bars
 

chris
you can use either top or bottom.

its easier if your using RCD's to bring the supply in the top of the RCD

then the bottom of the RCD you use the busbar to connect all the circuit breakers as Live then all final sub circuits connect to the top of the circuit breakers.


as for the neutrals you use NON RCD circuits connect to the normal neutral bar, then you take 1 x neutral cable into the top of the RCD, then 1 x neutral out the bottom of the RCD to its own neutral bar, then all sub circuit neutrals go to this neutral bar, remember all live subcircuit cables connected via the RCD must go on there own neutral protected bar.

the same for lighting if you have the lighting RCD then all light live cables go via the light RCD to circuit breakers & all neutrals from the lighting circuits also have there own neutral bar.

so in all you can have 1 x normal neutral bar + 1 x power (Sockets) neutral bar + 1 x light neutral bar.

DONT mix them or the RCD shall trip all the time.

remember all light cables on there own RCD + circuit breakers.
all power circuits on there own RCD.

normal circuits, (Air Con,Ovens) are not on RCD they go on there own circuit breakers & normal neutral bar.
it can be a pig of a job if your not used to doing a switchboard that requires all the RCD's..

if you need any help just ask

Re: trade test practise - consumer unit bus bars
 

thanks guys for clarification!

the tester gave me that busbar (no 9) in my hand :sneaky:, but it is not to be used for this exercise, because the RCDs were sitting in between the breakers, and they need only one power in, one neutral out.
One guy of us connected the RCDs on the bottom with that bar, thats a big error.

It was obiously a test setup, to see, how much we can through on the wall in 6 hours.

Re: trade test practise - consumer unit bus bars
 

Hi Chris or anyone else.

It's probably a bit late in the day to get clarification on this as I have my trade test tomorrow but you say a guy made a mistake by using busbar 9 Do you mean he connected the main switch to the RCD with the busbar underneath? And secondly how do you connect your RCD protected subcircuits to the RCD without using the the second busbar?

Sorry if I've misunderstood something really simple. I'm a bit stressed about this test and the simple has started to seem complicated!

Cheers
Jamie

Re: trade test practise - consumer unit bus bars
 

hi Jamie

sorry, a bit late, hope you made it. It took 6 weeks to get the confirmation if passed or not.


1.) as Arthur mentioned, in a proper installation: "remember all live subcircuit cables connected via the RCD must go on there own neutral protected bar" , thats why there are 3 bars in the box, earth, neutral, RCD neutral.

2.) you see that RCD, the busbar 9 is only connecting the left side of it with mains, the right side is for neutral current only!
This picture for one RCD solution shows how you collect RCD subcircuit neutrals at busbar 8 and bring them "back" over the RCD to the main neutral bar. I say back, because on a RCD where left mains goes in, there comes right neutral out. Both currents have to be equal (in and out going), otherwise RCD jumps out.

In my test we had 2 RCDs for only two devices, so there is no collection of neutrals on bar 8, both will be connected to their RCD and further brought back to the main neutral bar.

The other double pole switch has not been used, I picked this picture just to show the 3 busbars and what their usage is.

Chris

Re: trade test practise - consumer unit bus bars
 

Cheers for getting back to us so quickly.

I think it all makes sense now but at this stage after many hours going over power factors and equations nothing make sense.:)

Hopefully it'll all go OK tomorrow.

I spent last year back packing round South America with the missus and haven't been on the tools at all so I'm gonna be incredibly rusty!

I take it you passed then. If so nice one.

Btw anything else about the test I should know?!!!

Cheers mate
J

Re: trade test practise - consumer unit bus bars
 

Hi fellas, is the trade test used to assess you for your A licence ???, if so please keep this thread going its all good info.

Iain

Re: trade test practise - consumer unit bus bars
 

the trades test can be part of the ARTC assessment of the TRA.
With an ARTC you can apply for the a-grade license.

QLD seems to be the most difficult place for trade testing at all, and the tester himself said, their Skills Tech company at Acacia Ridge (at TAFE) would be the most difficult in QLD.
Thats why many candidates would choose another institute to do their testing, he said during the test!

So if you have the choice ...

At Acacia Ridge they are just building a huge training center, so why should they let you pass the test. They make their money with gap training.

I love it

Re: trade test practise - consumer unit bus bars
 

Thanks for the info, I have done the vetassess route and will be going to WA on a 12mth holiday visa, Iam looking to do the 2 week course whilst over there.

Iain

Re: trade test practise - consumer unit bus bars
 

Had my test today.

The guys doing the training for the most part were helpful and not going out of their way to trip us up.

First part was a theory test for one hour. The usual stuff ohms law, power factors, interpreting wiring diagrams. Nothing too outrageous.

Then we been some practical stuff. Safe isolation. relocating circuits on a pre-existing system and then test. All easy enough.

Last we were given one of those circuit boards where you connect the components with leads. We all did the first circuit fairly easily, which was a series of switches and relays controlling two pumps.

The second one involved wiring a star-delta starter. We all struggled to do this and I failed to complete it. I assumed we were going to just be wiring a pre-built star-delta starter control unit into a motor. WRONG!

Not sure what the deal is in other states for the trade test, I have no idea if it is standard but if this is anything to go by bone up on wiring motor control units.

They told be I'd find out what the score is in a few weeks and I was told I'd probably have to do some gap training. Oh well c'est la vie. As long as I get my electrical license at some stage! :unsure:

I'll post an update in a few weeks to let you know what happens next.

Hope people find this info useful and a big thanks to others who have posted here. I haven't written much but I've found the info here immensely helpful.

Cheers
Jamie

Re: trade test practise - consumer unit bus bars
 

Fingers crossed for you mate

Regards

Re: trade test practise - consumer unit bus bars
 

Hi Jamie, where did u sit your Trades Test? I sit mine on the 15th Feb at VICTEC in Carlton, Melbourne. Can anyone advise, all help appreciated thanks.

Bruce.:fingerscrossed:

Re: trade test practise - consumer unit bus bars
 

Not really much to add to what I've already written.

Theory is the same kind of stuff you would have done back home.

All the install and safe isolation is the same. Except you have to wear three pairs of gloves!!!!!:eek: And you should wiring lighting feeds to the switch and not the fitting, although I think one guy did it to the fitting and they weren't too concerned.

So read up on motor controls and practice assembling them if you can. I know it's something I've never done before and doubt I will again!

Good luck Bruce. It's not as bad as you think!

Re: trade test practise - consumer unit bus bars
 

Hi Arthur, just a quick question, is it Aus practise to separate lighting RCD's and power socket RCD's??
In uk, I have always been advised to split the lighting and power up so that down power is on with up lights and vise versa so that if one trips you still have some power and lights in a property.
Cheers
Paul