danthevan Posted March 10, 2015 Share Posted March 10, 2015 Wonder if anyone can offer advice on this. Been asked to play on the back of a moving flatbed truck at our local carnival. Seen it done plenty of times before off a generator, but just wondering how things like earthing work?! Quote Link to comment Share on other sites More sharing options...
Bassman Steve Posted March 10, 2015 Share Posted March 10, 2015 Just get your singer to take his shoes and socks off. :-) Not qualified to state for certain but I am thinking rubber tyres on the vehicle providing protection (as they do when driving through a storm). Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 (edited) I doubt anybody has thought about it. Rubber tyres wont help,in fact the opposite all it needs is a circuit, if the genny malfunctions, your getting fried. Earthing is a protection, the idea is the current heads to earth instead of using you as an earth. Not having an earth wont protect you from electrocution, in fact it makes it much more likely to happen, thats why we went from two wires to three in the 70's. Edited March 10, 2015 by spacey Quote Link to comment Share on other sites More sharing options...
danthevan Posted March 10, 2015 Author Share Posted March 10, 2015 Just been looking at an american sparky forum, and it seems that being a generator the current would find it's way back to the generator (the source of the circuit) and pop the breaker rather than trying to go to earth. Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 (edited) Yes, exatcly that via you first however it would have no way of knowing if you are a big fat valve amp drawing the current or a human getting electrocuted. . Edited March 10, 2015 by spacey Quote Link to comment Share on other sites More sharing options...
danthevan Posted March 10, 2015 Author Share Posted March 10, 2015 Fair point Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 Is it waterproofed ? Covered ? If not add that in and well, see yer in the next one bud. Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted March 10, 2015 Share Posted March 10, 2015 Could you not diffuse an mp3 and mime..? It's much simpler. A decent genny will have an earthing point, which should be connected to 'ground', or, in this case, to the flatbed. The planking, if it's wood, will likely be an insulation, however, so you'd be insulated anyway. Major earthing shocks are not a common occurrence with this type of equipment, as long as it's installed by someone competent. Miming is still much, much simpler. Quote Link to comment Share on other sites More sharing options...
amnesia Posted March 10, 2015 Share Posted March 10, 2015 The 'earth' is the chassis of the flatbed - its a reference potential, rather than actual dirt. The fact it sits on rubber tyres doesnt matter. Connect the 'earth' of the generator to the chassis of the flatbed. Any leakage current to 'earth' will then trip your protection - which you must make sure you have. I think RCD's work on the fact that current in the live conductor must be equal and opposite to the current in the neutral conductor. If this is not the case, then the current flow is 'probably' going through what should be dead metal (eg appliance chassis) and this causes the RCD to operate. Quote Link to comment Share on other sites More sharing options...
danthevan Posted March 10, 2015 Author Share Posted March 10, 2015 There must be a 'safeish' way of doing it, as it's been done by plenty in the past. The other thing i was thinking of was a sinewave inverter, but not sure what size it would need to be to run 3 amps and a PA, and whether there would still be the same earthing issues. Liking the iPod idea although don't quite think it would cut it! Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 Better still, battery equipment, the risk of creating a large toaster on wheels is not worth it. Quote Link to comment Share on other sites More sharing options...
danthevan Posted March 10, 2015 Author Share Posted March 10, 2015 @Amnesia, Going on your theory (to get it right in my head!) would we be better playing on a wooden bed truck, or a metal bed? Quote Link to comment Share on other sites More sharing options...
amnesia Posted March 10, 2015 Share Posted March 10, 2015 Makes no odds what you stand on...you've metal strings in your hands. Running a generator can be done as safely as being in a fixed instalation. Using an inverter will still need your 'earthing' and protection to be properly considered as the fault current will still be enough to turn your hair curly. People live on canal boats with 240V supplies - and standard practice is to have an isolated connection to the shoreline 240V supply. In other words true 'earth' isn't connected to the boat 'earth'. Earth of the generator connected to flatbed chassis, connected to the earth of your equipment mains plug. Proper protection in place and its all good. Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 The issue is, the Human body creates a very good earth conducting point, it is a bag of water, hence why so many people get electrocuted each year. 240v, no actual earth point (clue is in the name "EARTH") is in my opnion playing a bit close to the wind. Add in the fact it might start raining and you have all the recipee for a fry up. Quote Link to comment Share on other sites More sharing options...
charic Posted March 10, 2015 Share Posted March 10, 2015 Wireless? Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 [quote name='charic' timestamp='1425992555' post='2713124'] Wireless? [/quote] Belt for the braces ! Quote Link to comment Share on other sites More sharing options...
danthevan Posted March 10, 2015 Author Share Posted March 10, 2015 I do actually have a wireless kit, never thought of that! Quote Link to comment Share on other sites More sharing options...
amnesia Posted March 10, 2015 Share Posted March 10, 2015 Spacey - Yes we conduct electricity very well. 240V with no earth point is not a problem in itself - look at your dvd player for instance - lots of those units with METAL cases have two wires in only - no earth. Those cases float. Earth desn't have to be dirt. There is NO connection to true earth / ground / dirt on a canal boat for instance - and people aren't being randomly electrocuted on those. You just need a reference point for your protection circuits to operate against. The typical domestic protection operates due to an imbalance in current flow between the 'live' conductors. The green / yellow conductor is just a voltage reference point. The Earth only forms a return path when one of the other live conductor develops a fault whereby it comes into contact with the earthed chassis of an appliance (for instance). If it rains and you're stood outside with essentially 'open' electrical equipment, then you want your bumps felt. Charic - wireless is fine until you touch your amp to check why its gone off. Quote Link to comment Share on other sites More sharing options...
amnesia Posted March 10, 2015 Share Posted March 10, 2015 (edited) Wireless also means that should an amp develop a fault - the indication of that fault is that it goes quiet - but the amp stays energised with its case possibly live. What the first thing you do? Go and have a fiddle with the knobs. Cue curly hair. Edited March 10, 2015 by amnesia Quote Link to comment Share on other sites More sharing options...
danthevan Posted March 10, 2015 Author Share Posted March 10, 2015 (edited) Cheers guys. So generator is ok as long as earthed (bonded to truck), and if anything stops working, get the drummer to touch it before you do. Sorted Edited March 10, 2015 by danthevan Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted March 10, 2015 Share Posted March 10, 2015 (edited) [quote name='danthevan' timestamp='1425993233' post='2713143']...if anything stops working, get the drummer to touch it before you do... [/quote] Hurrumph..! Edited March 10, 2015 by Dad3353 Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 A canal boat has a correctly fitted and referenced RCD circuit by a qualified electrician, Somehow I think the Generater will be just lifted on the lorry ten minutes before to stop it getting nicked and a four way slung out. Comapring this to a correctly fitted system and saying it will be fine, never really works out in the real world, what you going to do if the Genny is not bonded to the lorry and tested by an electrician and signed off with a certificate. Hope for the best is the answer . Quote Link to comment Share on other sites More sharing options...
amnesia Posted March 10, 2015 Share Posted March 10, 2015 (edited) [quote name='spacey' timestamp='1425993635' post='2713149'] A canal boat has a correctly fitted and referenced RCD circuit by a qualified electrician, - You can do all your own wiring on a boat. There are rules but nowhere near as controlled as a normal domestic property. Somehow I think the Generater will be just lifted on the lorry ten minutes before to stop it getting nicked and a four way slung out. Comapring this to a correctly fitted system and saying it will be fine, never really works out in the real world, what you going to do if the Genny is not bonded to the lorry and tested by an electrician and signed off with a certificate. Hope for the best is the answer . [/quote] A slight off-topic distraction - You can do all your own wiring on a boat. There are rules but nowhere near as controlled as a normal domestic property. I'm not suggesting just a plug and play approach - obviously it needs to be checked by someone who knows what they are doing, but who do you get to do it? A domestic sparky? An autoelectrician? I'd have no problem running a generator on a flatbed, but my background would give me the confidence to know it was safe (or not). Edited March 10, 2015 by amnesia Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted March 10, 2015 Share Posted March 10, 2015 [quote name='spacey' timestamp='1425993635' post='2713149'] A canal boat has a correctly fitted and referenced RCD circuit by a qualified electrician, Somehow I think the Generater will be just lifted on the lorry ten minutes before to stop it getting nicked and a four way slung out. Comapring this to a correctly fitted system and saying it will be fine, never really works out in the real world, what you going to do if the Genny is not bonded to the lorry and tested by an electrician and signed off with a certificate. Hope for the best is the answer . [/quote] Indeed, or if the lorry is driven by someone with no adequate training or licence, a major accident could ensue, maiming or killing many innocent bystanders. The clue is in the term 'competent'. If it's, as you suggest, lashed up by just anyone, there's a potential hazard. If it's done correctly, by a competent, experienced person, the risks are mitigated. Everything in life has potential to go badly wrong. Should we all stay in bed..? Quote Link to comment Share on other sites More sharing options...
spacey Posted March 10, 2015 Share Posted March 10, 2015 Someone qualified to sign off 240V equipment, I am sure they are some regulations as to who can do such work . However I can not see them going to any such lenghs, these things are usually organised by people who smoke too much gear to worry about the band getting electrocuted . Then the other sceanrio, billy bodgit wires it up and says its fine, is he is going to prison if anything goes wrong ?. I would say, battery amps, it is going to need a fair sized genny to power a full band and PA rig, then there is the issue of it frying your bespoke amp head if it breaks and goes native. Quote Link to comment Share on other sites More sharing options...
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