sshortcircuit Posted February 4, 2013 Share Posted February 4, 2013 The "earth" within the microwave will be the return for the high voltage generated and contained within the microwave. One would need to touch them both to get a shock? Similarly with the inverter one would need to touch the case of the inverter and one of the outputs, or a faulty appliance, to get a shock. But back to the OP where no earths exists between then an RCD is of no point. Link to comment Share on other sites More sharing options...
Tracker Posted February 4, 2013 Author Share Posted February 4, 2013 This is the reply I had from Midsummer Solar today.It would seem that earthing the inverter to the chassis is not such a good idea after all? Hi Richard Most people don't bother with any kind of earth using these inverters. As its in a motorhome which will lack a proper earth, if there was a fault and you had an earth connection you run the risk of making the motorhome live. If the unit were to develop a fault, at the moment it would at least be more isolated. The RCD would only work I think if there was a proper earth connection. Regards David Link to comment Share on other sites More sharing options...
Brambles Posted February 4, 2013 Share Posted February 4, 2013 As its in a motorhome which will lack a proper earth, if there was a fault and you had an earth connection you run the risk of making the motorhome live. How would it? You would have to have hook up for the motorhome to become live and if you did have hook up then you would have an earth to the outside world and so motorhome could not become live as earthed. If you ran a wire from the casing of the inverter to the ground outside, then under fault conditions it is concievable your motorhome could beome live. The chap has answered a different question to what you thought you asked..I suspect. ARRRRRRRRGH! Link to comment Share on other sites More sharing options...
Brambles Posted February 4, 2013 Share Posted February 4, 2013 Just connect the earths to chassis and be done with it. We have established it is safe to do so, we have not established it is 100% safe to leave the earths floating. Link to comment Share on other sites More sharing options...
T8LEY Posted February 4, 2013 Share Posted February 4, 2013 Sorry to the disinterested and Rich you've been fed a load of crap. Excuse me but it might be the only way to get through some important points. DO NOT connect your inverter to the chassis. You have not established if your inverter output is earthed, regardless of your OP. If you connect the inverter output to earth (vehicle chassis), contrary to the inverter design, you could establish a dangerous connection. Your inverter has its own circuit protection for overload and short circuit, but does not include earth fault, you could introduce 230V to the metalwork of your motorhome. It's even got reverse polarity warning, for those that care! The manufacturer of the inverter has provided adequate fault protection, unless he tells you it needs something else. I'll say it again, any earth faults generated on the load (secondary) side of the inverter will be dealt with by the overload protection provided by the manufacturer. RCD devices are provided on electrical installations as supplementary protection to adequate earthing arrangements. They should never be relied upon in isolation. Link to comment Share on other sites More sharing options...
sshortcircuit Posted February 4, 2013 Share Posted February 4, 2013 Can you please explain how by connecting the inverter to earth where this 240 volts will be between. Reading the product info sheet I can see "over-voltage" and "short circuit protection" but cant see overload protection. Link to comment Share on other sites More sharing options...
Brambles Posted February 4, 2013 Share Posted February 4, 2013 T8LEY, Tracker has said he checked the inverter and the output sockets earth pin is connected to the case of the inverter. Of course you can connect this to the chassis. What would happen if you placed the inverter on the metal floor of a van, or the wall and bolted it down. You would then have the case earthed to the chassis. Link to comment Share on other sites More sharing options...
T8LEY Posted February 4, 2013 Share Posted February 4, 2013 sshortcircuit - 2013-02-04 10:56 PM Can you please explain how by connecting the inverter to earth where this 240 volts will be between. Reading the product info sheet I can see "over-voltage" and "short circuit protection" but cant see overload protection. By earth I presume you mean the chassis. If you connect the N/E output of the inverter to the chassis you are introducing a parallel return path which is just waiting for you to touch an extraneous conductive element in the vehicle and the earthed metalwork of faulty equipment. I said before, overload is covered by dc fuses, which I hope Rich is fitting. Do you see anywhere that advises additional protection? Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 Brambles - 2013-02-04 11:19 PM T8LEY, Tracker has said he checked the inverter and the output sockets earth pin is connected to the case of the inverter. Of course you can connect this to the chassis. What would happen if you placed the inverter on the metal floor of a van, or the wall and bolted it down. You would then have the case earthed to the chassis. That suggests to me the inverter accepts earth faults from any standard 230V domestic appliance, from the earth wire in the appliance flex, and passes it through its transformer as load on the primary, thus resulting in overload on the dc circuit. Why would you want to introduce another earth return path and, consequently, have to fit circuit protection to deal with any fault currents, when the inverter deals with earth faults as overload? You are getting into the realms of earth leakage circuit breakers and why they were dropped. Simples, to use a Trackerism, ensure you don't place/bolt it on bonded metalwork if you have such a MH. You'll have to correct me but of all the vans I've seen the finishes have been timber or something that looks like it and, if they're like mine, there's several mil of insulation before you get to anything that will rust. ps. this forum lacks a technical section. Link to comment Share on other sites More sharing options...
Brambles Posted February 5, 2013 Share Posted February 5, 2013 T8LEY - 2013-02-05 12:49 AM That suggests to me the inverter accepts earth faults from any standard 230V domestic appliance, from the earth wire in the appliance flex, and passes it through its transformer as load on the primary, thus resulting in overload on the dc circuit. How can it possibly in any remote sense suggest the inverter detects earth faults and passes it through its transformer. The earth wire in the appliance flex would connect to the socket and then to the case of the inverter. If the case was left isolated then what is the point of even connecting the socket earth. It is so the case of the inverter can be connected to Ground, be it the chassis of the vehicle or in your own home would be the main earth circuit. It is a safety function to make sure all aplliance cases and any metal in your home, motorhome or otherwise remain at the same potential. Absolutely nothing about the inverter detecting faults. If all metal related to an electric powered appliance, or a metal structure is conected by an earth loop then there is no way you can get an electric shock from touching any metal in your home.... e,g radiators, sinks, steel beams, boiler, washing machines, kettles, cooker etc. In your Motorhome...fridge, heater, taps, sink, something connected to the chassis, a plugged in appliance, a microwave, inverter case, etc. The safe option is to connect all metal items together. Then no risk of a shock. It is a very simple principle to understand. Why would you want to introduce another earth return path and, consequently, have to fit circuit protection to deal with any fault currents, when the inverter deals with earth faults as overload? You are getting into the realms of earth leakage circuit breakers and why they were dropped. Covered by above comments. What additional circuit protection are you referring to. It has been established the RCB is of limited value because the inverter output is floating 230 vac. It would only be of use if the designated neutral output was also tied back to the chassis. before doing this one would have to check with the inverter manaufacturer it could be done as some inverters may have filtering on the output which would be affected and may not be safe to do. Most you can as the filtering is between the two supplies, but some may have a delta filter connected to the case. The safe option here seems to be to leave the 230v outputs floating and hence RCB would not work. If it was established the invertor was safe to connect the 'neutral' to teh chassis/0volts then you could do so and the RCB would function as designed to in the event of a fault in an appiance to earth. Simples, to use a Trackerism, ensure you don't place/bolt it on bonded metalwork if you have such a MH. You'll have to correct me but of all the vans I've seen the finishes have been timber or something that looks like it and, if they're like mine, there's several mil of insulation before you get to anything that will rust. You have to remember the number one priority for safety of electrical appiances. All metal cases etc and metal structures must be connected together so thay are all held at the same potential so there is no risk of a shock under fault conditions. Fuses should be fitted, or circuit breakers used to prevent current overload. It is not feasible to use the overload cutout of a inverter because it wil be at the max rating. e.g. 1500 watts = 6.5 amps. If using to power say a 400 watt appliance then overload detection must be set for 400 watts = approx. 2amp fuse. Fortunatly if using standard sockets and plugs as in the uk we have fused plugs. Sincere apologies if I have read your reply wrong. Link to comment Share on other sites More sharing options...
sshortcircuit Posted February 5, 2013 Share Posted February 5, 2013 T8LEY Interesting views. "I said before, overload is covered by dc fuses, which I hope Rich is fitting. Do you see anywhere that advises additional protection?" Where are these fuses fitted? Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 Brambles - 2013-02-05 2:48 AM T8LEY - 2013-02-05 12:49 AM ---That suggests to me the inverter accepts earth faults from any standard 230V domestic appliance, from the earth wire in the appliance flex, and passes it through its transformer as load on the primary, thus resulting in overload on the dc circuit. How can it possibly in any remote sense suggest the inverter detects earth faults and passes it through its transformer. ---Sorry but I did not say detects. I have explained previously how I see the protection working. However, I think we are both making assumptions about the equipment and we both fully understand the principles of EBADS as you described. What additional circuit protection are you referring to. ---You will need circuit protection to achieve the ADS part of the system you explained earlier. It has been established the RCB is of limited value because the inverter output is floating 230 vac. It would only be of use if the designated neutral output was also tied back to the chassis. before doing this one would have to check with the inverter manaufacturer it could be done as some inverters may have filtering on the output which would be affected and may not be safe to do. Most you can as the filtering is between the two supplies, but some may have a delta filter connected to the case. The safe option here seems to be to leave the 230v outputs floating and hence RCB would not work. If it was established the invertor was safe to connect the 'neutral' to teh chassis/0volts then you could do so and the RCB would function as designed to in the event of a fault in an appiance to earth. ---As you say, this is some of the stuff that needs confirmation; to allow any of us to comment with total confidence. Fuses should be fitted, or circuit breakers used to prevent current overload. It is not feasible to use the overload cutout of a inverter ---I think we are at cross purposes again. I was not suggesting the inverter overloads would protect against earth or short circuit faults but that the overall installation design should. Sincere apologies if I have read your reply wrong. Hope the above clarifies my previous comments and sorry for the massive edit but I was trying to keep it short. Link to comment Share on other sites More sharing options...
sshortcircuit Posted February 5, 2013 Share Posted February 5, 2013 You appeared a bit emphatic that Rich fits "dc fuses". Where is he going to fit these fuses? Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 sshortcircuit - 2013-02-05 11:42 AM T8LEY Interesting views. "I said before, overload is covered by dc fuses, which I hope Rich is fitting. Do you see anywhere that advises additional protection?" Where are these fuses fitted? In the dc supply cables, for the inverter, near to the battery. Sorry, perhaps I should have been a bit more specific in the description and said the inverter power supply dc circuit protection. Link to comment Share on other sites More sharing options...
Brambles Posted February 5, 2013 Share Posted February 5, 2013 Thanks T8LEY for further explaining. SS, If you have DC fuses in the battery feeds to the inverter, any overloading on the inverter output will be refected in the current drawn from the batteries so the fuses then protect in an indirect way, and also give protection should an inverter fault appear. Two birds with one stone! Link to comment Share on other sites More sharing options...
sshortcircuit Posted February 5, 2013 Share Posted February 5, 2013 Thanks 1500w inverter = 100A+. Have you seen these fitted? Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 Brambles - 2013-02-05 12:44 PM Thanks T8LEY for further explaining. SS, If you have DC fuses in the battery feeds to the inverter, any overloading on the inverter output will be refected in the current drawn from the batteries so the fuses then protect in an indirect way, and also give protection should an inverter fault appear. Two birds with one stone! Couldn't have put it better. Cheers Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 sshortcircuit - 2013-02-05 12:50 PM Thanks 1500w inverter = 100A+. Have you seen these fitted? Yes in every house I've wired. Don't expect the dc cables will be easy to handle either, especially as they need to be bunched conductors rather than stranded, but hey, did anybody suggest this was going to be easy? If he's stuck for space, breakers would be more compact. Link to comment Share on other sites More sharing options...
Brambles Posted February 5, 2013 Share Posted February 5, 2013 sshortcircuit - 2013-02-05 11:50 AM Thanks 1500w inverter = 100A+. Have you seen these fitted? Ermmm. yes actually I have. Anyway just thought about it and realise with the tolerance on a 100 Amp fuse and time to blow it may not offer the output that much accurate protection. I notice Trackers inverter as 4 input fuses fitted in the picture of it on suppliers website ...purple ones. I assume these are 100 Amps as purple is designated to 100 Amps for automotive fuses. Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 Brambles - 2013-02-05 1:58 PM sshortcircuit - 2013-02-05 11:50 AM Thanks 1500w inverter = 100A+. Have you seen these fitted? Ermmm. yes actually I have. Anyway just thought about it and realise with the tolerance on a 100 Amp fuse and time to blow it may not offer the output that much accurate protection. I notice Trackers inverter as 4 input fuses fitted in the picture of it on suppliers website ...purple ones. I assume these are 100 Amps as purple is designated to 100 Amps for automotive fuses. Hadn't checked before but the supplier does made up leads, 35sq mm for 125A, with battery terminations and fuses. So they don't expect you to rely on the onboard inverter protection, if that's what the coloured fuse carriers are? Also, how do they get 1500W with a 100A limit on a 12V supply? Link to comment Share on other sites More sharing options...
Brambles Posted February 5, 2013 Share Posted February 5, 2013 I suspect they have two sets of 100 amp fuses in parallel. Need to check what the peak power is of the inverter as may be 4 in parallel which would seem rather high. Link to comment Share on other sites More sharing options...
Brambles Posted February 5, 2013 Share Posted February 5, 2013 100 amps is actually violet not purple. Purple is 120 Amps, so two in parallel would be 2880 watts, so not far off the 3000W surge spec. As the fuse wil be 1.2 to 1.5 factor over rated to blow it all sounds about right. So I go for 2 lots on of 2 in parallel. Max auto blade fuse I know off is 120 Amps. (Are you managing to keep up Mel, or are you climbing your garden ladder and junping of the top yet.) Link to comment Share on other sites More sharing options...
Tracker Posted February 5, 2013 Author Share Posted February 5, 2013 To earth or not to earth? That is the question Whether tis safer to bugger about with the earthing and fusing or whether tis best left alone? These inverters are also designed for use in boats - GRP boats with no chassis to earth to - which kinda makes me think that earthing to the chassis would not be right? I wish I knew? I appreciate everybody's input and I am amazed that we are now on page three of this thread! I look forward (more in hope than expectation, it must be said) to you guys that understand these things reaching a consensus as you can't all be wrong! Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 The Manf lit says 125A so they most be other than auto type, but that would give them 1500W on each leg. They don't give a lot of detail on their data sheets so without knowing what length of time they claim, the fuse factor could be 2 !! That seems terribly coarse. I see what you're saying about the number of carriers on the inverter, so the rating could actually be 63A ie two fuses per pole, to achieve the same protection as their made-up lead fuses. Just had another thought. The lead fuses would have to be slower than the device's for them to be worth having. Hold in there Rich Link to comment Share on other sites More sharing options...
T8LEY Posted February 5, 2013 Share Posted February 5, 2013 Tracker - 2013-02-05 5:02 PMTo earth or not to earth?That is the questionWhether tis safer to bugger about with the earthing and fusing or whether tis best left alone?These inverters are also designed for use in boats - GRP boats with no chassis to earth to - which kinda makes me think that earthing to the chassis would not be right?I wish I knew? I appreciate everybody's input and I am amazed that we are now on page three of this thread! I look forward (more in hope than expectation, it must be said) to you guys that understand these things reaching a consensus as you can't all be wrong!"I know what you're thinking. Does it need earthing or does it not? Well, to tell you the truth, in all this excitement, I've kind of lost track myself. But, being as this is a Midsummer inverter, the most powerful in the world, and to get it wrong would blow your head clear off, you've got to ask yourself one question: Do I feel lucky? Well, do ya punk?" Link to comment Share on other sites More sharing options...
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