I would have thought that everything should be off one phase, except for the three phase unit that requires all three. To have multiple phases connected to different outlets in the house would be dangerous I think due to the high voltage between the mulitple 'live' connections. In fact I would have expected it not to be legal.
Nope not how 3 phase 4 wire works (in Australia anyway)
The 4th wire is the neutral
Each phase is 230/240v - so you can pull them with the neutral line.
there is no high voltage difference between them as each are referenced to ground. (And it is now mandatory in Australia to use RCD/GFI breakers on all power outlets) so mixed grounds/phases will instantly trip the RCD
Craig
I agree with Colin - I would have thought everything in the house should be off the same phase otherwise if you had two phases in the same room and managed to touch both 'lives' you would be across phases 415v - ouch!!!!
PS
I really think we have gone quite far off topic now and should probably call a halt to this.
The two lives are out of phase, so one can be +230 while another is -ve, much more than 230 between them.
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Yep probably right - but i wonder if you guys are thnking more about the US style of obtaining 220v ?
I will find some info to paste up that shows it and start another thread.
Craig
Yep i was aware of that - most people are used to still taling in 240v/415v for 1/3 phase
Its a bit stupid really - as accordng to my solar inverter the majority of the time the grid seems to be hovering in the 240v range more than the 230v anyway
Craig
It says it is 400 across the phases.
[Edit] I thought you were saying that there was not a large voltage between live wires. If you had accepted that then I am not sure what you are saying, so, as you suggested, start a new thread if necessary.
Well I live in the UK and I think Colin does also.
We only have single phase in our homes although there is normally 3-phase buried in the road.
I think when a housing estate is built here in the UK, they put one road on one phase and the next road on another phase, etc.., so all the phases are balanced.
Hey Guys,
Here is a picture of the 3 phase switchboard in our house
You can see the 3 phases entering at the top left (the 4th wire goes to the neutral bar on the right), earth is provided by earth bar on the left
As you can see the way the boards are designed it is impossible to hook a single circuit to two different phases (and as RCDs/ELDs etc are mandatory in this sort of config - no way of getting it wrong and still powering the circuit.
Craig
As far as I understand, the danger is that two circuits, e.g. for lighting or sockets/outlets could be correctly wired to different phases but end up physically close to each other at some point. Using two devices plugged into different sockets could have 415V between their live lines.
We have a big vestibule-type area in my office where the light switches at opposite sides have hazard labels on them because they're on different phases for some reason (it's quite an old building).
I had exactly the same situation in a training school (very old building) where I worked here in the UK.
The mains sockets on either side of some of the classrooms were wired to different phases.
And to avoid the risk of electrocution - stickers were placed on the walls !!!!!!!!
@molesworth is correct. Consider, for example, if you have one phase outlets in one part of the house and a different phase in another. Now plug a router into one and the PC into the other. Now connect an ethernet cable between them and you have the possibility if there are two faults (one in the router and one in the PC) that you can have 400V available to cause death. Most serious accidents occur when a number of faults or coincidences occur at once.
Nope - can not happen - every circuit has an RCD on it - lights included - if you try to connect across phases like you have described the RCDs are immediately tripped.
We had exactly this happen with some downlights in our outside eaves - one line on one side of the house and around the front had been wired into one phase, the other side of the house into another phase - the apprentice electrician spent nearly two days trying to work out why every time he connected up a downlight and powered it on the two circuit breakers would trip
His boss gave him a good whack around the head for wasting so much time without raising it with anyone !!
As you have said - in the old days this was possible and was controlled with warning signs !!
Craig
What cannot happen?
Do RCD units never fail (if they never fail why do they have a button that says they should be regularly tested, but no-one ever does)?
As I said, serious accidents are usually the result of multiple faults and coincidences.
Will you happily stick your finger into a mains outlet knowing that the breaker will save you?
Not really sure what we are arguing about here - this is the approved standard in Australia which has some of the toughest (some might say draconian) eletrical standards and laws in the world.
In your example above - not one but two RCDs would have to fail in the closed position for current to flow
Craig
Hello,
This dashboard looking attractive, currently i am receiving three values from database in Java-script format and i have created dashboard using gauge and text ui_nodes.
Now i wanted to created live dashboard similar to your energy plot with three value ( Amp, Kw, kVR)
Can you please help me in terms of node adjustment.
So what exactly is the issue??
I get amps and voltage from the TZEM-004T so that means Kw can be calculated by simple maths.
I think the PZEM also records and sends reactive power - although I've not used it.
Can you publish your NR flow?
Hi, I want to display a live trend of consumption of all parameters ( AMP, KW, PF) in a single line chart.
I have created a dashboard separately for this, now want to merge all these parameters in a single chart.
Need your help to make line chart which shows three parameters in a
single chart.
Make sure the three messages have separate topics and send them all to the same chart.
