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240V Protection

Discussion in 'Fuel System & Electrics' started by CoffsKombi, Aug 31, 2008.

  1. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    I agree. I think that it was a backward step when they allowed electricians to self assess back in the 80s.

    All caravan parks in NSW require leads to be legal, but it is not enforced.

    Nowadays you can buy diy kits for "soft wiring" in vans. A bit of a grey area legally and could be very unsafe.
     
  2. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,840
    Location:
    Penna, Hobart
    I haven't heard the term self assess? If a sparky tests his own equipment and tags it with his details he is responsible for it. If he wires a building and he signs it off to be compliant he risks his licence if there is ever any issues found. They run audits on random installs to make sure it is compliant, and if any incident occurs he still has his name on the job and is responsible.

    Dont see a problem there.

    Adrian
     
  3. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    In NSW there is no record of which electrician has done the installation. The supply authority used to have inspectors that checked the work every time. I know a few electricians and none of them has had an audit. There is a lot of dodgy work around.

    Not all electricians are licenced to tag as it is a separate qualification.
     
    Last edited: Jun 12, 2019
  4. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,840
    Location:
    Penna, Hobart
    AAAH there is the difference. In Tas electricians do sign off their own work (by self assessing i suppose) and all work has to have a notification of work done and by whom given to the client and a record kept by the electrician. We still have inspectors that inspect work although not every job. Very nasty if they find anything. Big fines and then have to have every job inspected.

    Adrian
     
    oldman likes this.
  5. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    I'm an electrician (not licenced for buildings) but I have had to rewire most of the additional work done on my house. A light had the active from circuit 1 and the neutral to circuit 2. It's only that I am an electrician that I picked this up. Most people would only find out after somebody died.

    I have never seen an electrician do a maximum demand calculation since the self assessment.

    The old method of supply authority testing was a good method.
     
    Last edited: Jun 13, 2019
    oldman likes this.
  6. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,840
    Location:
    Penna, Hobart
    Been a sparky for almost 35 years, not on the tools per se for the past 10. The inspector method still missed a lot, so I don’t think it has made a huge amount of difference. Btw supply authority inspectors only ever checked major installs. A lot of the problems found are with the alterations and additions. No one has ever checked those.

    Adrian
     
  7. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    I thought you were an auto electrician.

    I remember the inspections on my house for extra power circuits, garage, lighting. I think that any addition was supposed to be inspected in NSW. Never got a defect. I was a sparky for 44 years and had to deal with tools.
     
    Last edited: Jun 14, 2019
  8. rstucke

    rstucke Well-Known Member

    Messages:
    1,148
    Location:
    Wamberal NSW AUS
    I'm an auto sparky (amongst other quals)
    I've done test and tag (Did a course for qual under test n tag for competent person) for some years now
    I've seen a sh#*T load of stuff that's dangerous. Arguments, arguments. So I only do my own stuff now.
    I let people know where I go, they can have there leads tested ( I carry a PAT unit with me and the stickers for the leads)
    I believe a lot of this is hokum as no authority does any checking. But I would guarantee If something happened to an article I verified, I'd be toast.
     
  9. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,840
    Location:
    Penna, Hobart
    The test and tag system has a lot of issues, but the most obvious one is it may be fine when it was tested, but you can tag it and 5 mins later someone damages it, or modifies it, and it is not safe anymore. Is the inspector liable? I can’t see how as it was compliant at the time he inspected it.

    I am sure the intent was to make sure things were checked from time to time by a suitably qualified person, but it cannot guarantee that it is compliant between inspections.

    Anyway, I think we have made our point.

    Adrian
     
    syncro and oldman like this.
  10. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,372
    Location:
    Mannum South Australia
    Hello all, haven't been on the forum for a quite a long time, but this one caught my eye. A RCD won't actually work in a transportable premises that plugs into an RCD protected supply. An RCD needs to see a fault to the earth return circuit, because an MEN system has the earth connected to the neutral so the test is between active and neutral really.
    A transportable premises is the class all caravans, motorhomes and house boats fall into but also covers transportable buildings.
    These must all have double pole switches including the circuit breaker/s to allow for a wrongly wired extension cord or supply to ensure the active is cut. All good so far, but an RCD is looking for a fault on either the active or neutral after the RCD. An RCD fitted up line can not see a fault unless there is a bonded earth neutral just before it so it can see a fault to earth after the RCD. The problem is the second earth neutral bond would be seen by the first RCD as a line fault and trip the supply. An earth fault after the first RCD relies on quality and length of the earth return to transfer the 30mA required for it to trip. To get 30mA through a long extension lead with its additional resistance will result in a lot more than 30mA being required at the fault. If anyone has had an electric shock that tripped the RCD they know just how much that hurts and takes the breathe away. More than 30mA through the body can be fatal, 30mA can be fatal if the heart etc isn't in good nick, more than 30mA just moves the fatality risk further up the healthy person scale.
    The RCD in the transportable premises will only trip on an overload, if some one gets connected up between the active and neutral the second RCD would just see them as another appliance and only trip if overloaded.

    T1 Terry
     
  11. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    Doesn't matter whether you think that it works or not, It is a legal requirement. End of story.
     
  12. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    If it's 30mA at one end then it's 30mA at the other. Go away and read about Mr Ohm.
     
  13. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,372
    Location:
    Mannum South Australia
    Hmm... sit down for a few minutes and take another look at ohms law. What happens when voltage and current pass through a resistor? The RCD is not looking at voltage and draws no current until it is tripped. Once in the act of tripping it requires both voltage and current to trip it, watts. What happens when watts travel through a resistor if the watts at the other end must be the same yet the resistor causes a voltage drop? won't the current need to increase at the supply end to compensate? the 30mA is at the load end, the person at the other end is creating the supply by creating the link between active and neutral/earth. If the supply current needs to be more at the supply end than the load end because of the resistor in between, that current must pass through the person.

    As far as the RCD being mandatory, more to do with not really thinking the problem through to find a better solution, much like many of the Australian Standards, that's why they are rewritten so many times. These were made mandatory to cover the risk of plugging into a non MEN supply, but with no earth neutral bond they are not going to function anyway are they? Transportable premises are relatively new on the scene and very few licenced sparkies actually work on them or even familiar with AS 3010:2017 so not a lot of practical hands on feed back is received when it comes to rewrites.
    A far better choice would be an RVD (residual voltage device) because it is only looking for voltage on the earth wire and is the only device suitable for a floating supply, like that from an inverter or generator that doesn't have an earth neutral bond before an RCD. All transportable premises are wired as a floating supply, a switch earth/neutral is required to make them sometimes an MEN and sometimes a floating system, depending on the supply, can you imagine those that write the standards coming to grips with how that would work?
    Those that write the standards have not as yet even addressed the use of an RVD as an alternative to an RCD. Some try to say it's just snake oil smoke and mirrors stuff, such is the way of those who are not willing to learn something new .....

    T1 Terry
     
    David H likes this.
  14. drivesafe

    drivesafe Active Member

    Messages:
    156
    T1 Terry is on the money with safety.

    The RVD actually exceeds the existing standards for safety and combines the use of an RVD-RCBO and in Victoria you need RCD/RCBO approvals proven by
    ESV to be sold in Victoria. RVD-SAFE is listed on the ESV as an approved RCBO.
    Also, most people are unaware that RCDs do not work in wet situations, but an RVD corrects this dangerous drawback.
    Here is a link to the RVDSAFE website. Have a look at the INLET.
    The INLET allows an AC power supply to be installed in your Kombi and you do not need an electrician to install it.
    https://www.rvdsafe.com.au
    Here is an interesting video about RVD use.
     
  15. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,372
    Location:
    Mannum South Australia
    You near knocked me off my chair Tim, you actually agreed with me about something :lol: Hope all is well with you.

    T1 Terry
     
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  16. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,840
    Location:
    Penna, Hobart
    The RVD sounds like a great idea, but I am not happy with the comment about RCD's not working in wet areas. What do you base that on?

    The measure the imbalance between the active and neutral, so if there is current over 30mA (for a standard unit) not returning via the neutral it must be returning through earth, possibly via a human, and the unit trips. (RCDs will not trip if the human is across the active and neutral conductors so they are not a silver bullet against electrocution and in that case a RVD isn't going to help either as there will be no earth current). Wet areas will make no difference, except providing an easier path to earth.

    The MEN connection is important but can be anywhere before the RCD electrically and not after, for example in an transportable building as it will trip the RCD immediately the power is turned on. The building in that case is effectively an appliance and the metal structure is bonded to the earth of the supply cable so provides a path back past (not through) the RCD to the MEN point in the Main Switchboard.

    If RCDs are are negatively affected in wet areas, it mean they are useless in bathrooms or outdoors and be pointless in caravan parks or marinas where they are mandatory and have been for years.

    Happy to be updated on recent findings, but it sounds like there is something missing from the information and may be why many people are unaware. No mention of it that I can find suggesting this.

    Adrian
     
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  17. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    RVD will trip before there is a path to earth. (person) RCBO is 99% safe. RVD adds the extra 1%.

    An RCD will work when there is 30mA differential, wet, dry or slightly moist.

    Try getting your Kombi registered without documentation from an electrician.
     
  18. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,840
    Location:
    Penna, Hobart
    Not so sure about your 100% safe. I doubt if you can ever be close to 100%, but these devices make it as close as possible. If you get hooked up across active and neutral, with say rubber soled shoes and/or no connection to earth for example, you will not trip either of these devices. This is the way it needs to be as your body will appear as a high resistance load and you don't want to be tripping the breaker every time you put a low current draw device on it.

    Bottom line, I think we can all agree, mains voltage electricity is dangerous and should only be installed or worked on by suitably qualified people. In a perfect world they should be the only ones who should have access to potentially live parts.

    Adrian
     
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  19. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,372
    Location:
    Mannum South Australia
    Umm..... If these is gas fitted you must have a current gas compliance, but I've never had an enquiry regarding electrical compliance when it comes to rego, even for original rego in a new state. I've never even had a request for one when insuring a mobile home and two of our motorhomes are full 240vac house powered, no gas at all.
    When ever we do a conversion to lithium and an inverter is involved where it is wired to shore power and house power for the UPS functionality, the local sparkie comes up and issues some sort of certificate that basically says he has tested the system, all the earths are functional and there are no earth leakages detected at the time of inspection. That just seems to be a "get out of Jail free" card for us if anything happens up the road involving someone getting an electrical shock from the RV.
    Because just about all quality inverters with a UPS function have a switching earth/neutral link, the RVD becomes unnecessary as the already fitted RCD's will function properly. These inverters actually test if there is a reliable earth/neutral link in the supply, that the supply is wired to the correct polarity and the waveform is clean and within the specified frequency and voltage range. Many will refuse to switch to mains power when a generator is supplying the shore power because the waveform or voltage/frequency is not stable enough.
    These days the quality inverters seem to put out a cleaner supply than the mains and many full time RV owners have gone to simply wiring the shore power to either a very smart mains charger that can handle just about any voltage, waveform and frequency and very efficiently converter that into battery charging voltage/current, or, really dumb chargers that are so robust in their primitive design that they seem to run on anything and turn that into battery charging voltage/current, just rather inefficiently. Meanwhile the house power is via the inverter at all times so the voltage and frequency remains stable.
    At this point everything, apart from the mains charger, is off grid and the whole Aust standards and rules seem to fall into a grey area where no one seems to actually have any real authority.

    T1 Terry
     
    Mordred likes this.
  20. syncro

    syncro Well-Known Member

    Messages:
    9,481
    Location:
    Southern Highlands
    Have a look through the Kombiclub forum. I didn't believe it at first either but there are too many members that have come across this.

    I still think that it would be legal to have an original Sopru that didn't even have a circuit breaker. Electrical rule changes are usually not retrospective unlike gas.
     

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