Guest Posted October 28, 2008 Posted October 28, 2008 [quote name='Mottlefeeder' post='310821' date='Oct 20 2008, 08:42 PM']The earth connection to the equipment is there to make sure that if there is a fault, the fault current will be high, and will blow the fuse quickly, which disconnects it. A plug-in tester is fine, provided you know what it is testing. The ones that have three lights on them will confirm that you have an earth connection, but will not tell you whether it is the last strand of a frayed cable (no use at all) or a thick cable with good connections at both ends. When you turn up at a venue, any test device that does not measure how good the earth is (earth fault loop impedance) is probably no help to you at all. Granted, it will tell you if there is no earth at all, but then so will your plug-in RCD which will not latch in.[/quote] Good point, you can get martindale testers which provide more detailed results but they are expensive! I was just recommending them as a belt AND braces approach. I used to build hydraulic pumps a while ago and to test then we used 'snap boxes' basically you put the bear wires of the 3 phase cable in them, one particular pump motor had a very long cable on it so i cut it short and striped the cable to put it into the test box. What i failed to realize was i had picked up the offcut and put that into the test box. Of course when i traced the cable to find out why my motor wouldn't run i grabbed hold of the 3 phase supply. It threw me a good distance across the workshop where i lay slumped against a wall, conscious but unable move while my heart did a good impression of a drunken drummer Ive always been a little more cautious since Quote
51m0n Posted July 31, 2009 Posted July 31, 2009 It was all so simple when I was gigging a lot in the early 90's, course we was immortal too so none of thie lectricity gubbins could harm us, however dodgy the toilet we played in. I have no idea how I have survived this long - really My boy just got told he'll have to have his lovely LH500/Berg rig PAT tested if he wants to use it at the local Rock School course/gig. Shame, I think Herbie F would have liked it ! Quote
High score Posted July 31, 2009 Posted July 31, 2009 [quote name='woolleydick' post='307577' date='Oct 16 2008, 08:28 AM']Thought I had better share this. I know there have been previous threads but when it comes to this sort of thing there is no problem repeating the advice. In mid song last night (first track of the rehearsal) I went to move the mic' on it's stand in front of my amp as I was not happy with the tone. I experienced a serious electric shock which caused me to spin round holding the mic' stand and fall over onto it. At this point I stop remembering anything until I came round surrounded by freaked out band members calling for an ambulance. They tell me they first thought I was having some sort of fit until they touched me and also received a shock. They then "pulled the plug" on the stage power. I was probably live for around 10 seconds max (to them it seemed longer). Any longer than this and I suspect I would not be telling you about this. I reportedly stopped breathing for a few seconds after the power was disconnected. I suffered multiple burns to my hands and chest (from falling on the mic' stand/mic' and still being in the circuit). We locked the rehearsal facility (which was designed and built by the lead singer), and the full investigation starts today as to where the fault comes from. I will let you know the results. NOTE - I did not have my own RCD in the circuit nor did the PA. I suspect the rehearsal facility does not have a functioning RCD. Always check you are properly protected before you start. I was seconds away from death last night - please do not repeat my experience Thanks. PS the Status Streamline survived unscathed although I did change the strings and clean off the scorch marks from the neck once I got home.[/quote] Sorry to hear about this but you had a very very lucky escape but at least you live to fight another day....... I have done live sound for many years and would always insist the band used my connecting cables to connect their kit to regardless of what the venue had because I ensured the wring could handle heavy current without overheating and always used rcd on every single extension. This might sound a bit anal but I lost count the number of times I saw players with pints on their amps as well as the inevitable piss head wandering around front of stage with beer in hand !! If your mate wired this up as an installation, he clearly does not know what he is doing nor has he had it checked out by a qualified sparky. Something seriously wrong if the stand and mic have gone live................ Lastly, you should still get checked out cos severe shock can create irregular heart beat as well.......... Quote
ironside1966 Posted July 31, 2009 Posted July 31, 2009 A Tip When wiring a plug always make the earth long enough so that it is the last to go should the cable get pulled. As a rule I always leave a good cm or two extra length on the earth. Quote
bassace Posted July 31, 2009 Posted July 31, 2009 Ah, the well known Bowie song 'The man who failed to earth'. Quote
BarnacleBob Posted July 31, 2009 Posted July 31, 2009 And leave quietly! remember way back in 90s playing the staff club for the Bar-L prison nr Glasgow and ready to kick off picked up a mikestand to move it and POW!!! My thumb was resting on the E of my Steiny( still have the scar) and it felt like I had been grabbed around the body and was being lifted up, didn't shake or anything just totally paralysed and nobody realised anything was wrong til smoke started coming off me. My girlfriend, a nurse, who didnt normally come to gigs was the only one to realise what was happening and screamed to turn the power off. When the power went off I just fell straight forward stiff as a board comedy style into the keyboards Anyway Ambulance called etc and, I heard later, as it mee-mawed its way to the local Royal Infirmary the entertainments convener asked our guitarist "What time do you reckon that boy'll be back, then?" Twitched for weeks after that!! BB Quote
JanSpeeltBas Posted July 31, 2009 Posted July 31, 2009 Many moons ago I played a session on a borrowed Bassman 135 with a faulty fuse, vibrating loose. Tried to reinsert, touched it and woke up 10 feet from the amp...afterwards all my longforgotten childhood memories came back to me.. :wacko: .my trusty Tokai survived it too... Quote
Zoe_BillySheehan Posted July 31, 2009 Posted July 31, 2009 eek :| just read this. Glad your ok though! apart from the burns Z x Quote
BarnacleBob Posted July 31, 2009 Posted July 31, 2009 (edited) It was a Steinberger not a burns Boom, Boom BB Edited July 31, 2009 by BarnacleBob Quote
Mr. Foxen Posted July 31, 2009 Posted July 31, 2009 A mate managed to blow up his Peavey by running most of a PA off it at practice, the trip went, here is his drummers (my ex drummer who forgot his kit to a gig)'s account: 'the power transformer was red hot 15 minutes after the amp transistors had cooled down but even after that had cooled, still no go and we bypassed the trip we removed the connectors and, erm, connected them :)' His suggestion to fix being bypassing the trip that had tripped, then wondering why it still broke. Quote
iamapirate Posted July 31, 2009 Posted July 31, 2009 crazehhhh!! I had something happen to me similar, but completely musically unrelated and not very life-threatening... kinda. I was basically trying to move a computer desk out of the way. Now screwed onto the back of it were 3 wires in some kind of white plastic transluscent box. So I thought to myself - take it off with a screwdriver, surely! (with the mains still on) I proceeded, thinking it was some kind of internet cable fix (The rabbit has bitten many a cable in this 'ere house) only to find to my suprise that it was mains electricity that my Dad had decided to make a cable with - a kettle-to-kettle lead. So the wires connected, sparks flew (one down my hoodie sleeve - burning me - no marks) and others going everywhere - a couple on my face. The funny thing was that because they were metal screws, if I hadn't chosen to use the plastic screwdriver, (I was offered 2 different sizes - decided to take the one that was larger that hapened to be plastic), or only used 1 hand to unscrew it, or if I hadn't worn that particular hoodie, then I would have risked having an electrical spark in my eye, or having mains running down both my hands and through my body... which would suck! Come to think of it, i keep getting shocks from the HiFi every now and again. Also, when I was 6 I once got a shock from an 'unbulbed' lamp. AND my guitarists' JCB extension gave me a huge shock about a year ago *runs to get a surge RCB thingy* Quote
woolleydick Posted August 1, 2009 Author Posted August 1, 2009 Hi folks as an update, we finally traced the fault to a 4-way extension block. This unit, bought in the UK and of a reputable brand was a filtered type. The filtering was achieved by a capacitor on each socket between live and earth. One of these caps had shorted thus connecting live and earth. Now of course we do not know why it shorted, it is extremely unlikely that it did it all on its own. Quote
TimR Posted August 1, 2009 Posted August 1, 2009 (edited) [quote name='woolleydick' post='557641' date='Aug 1 2009, 10:33 AM']Hi folks as an update, we finally traced the fault to a 4-way extension block. This unit, bought in the UK and of a reputable brand was a filtered type. The filtering was achieved by a capacitor on each socket between live and earth. One of these caps had shorted thus connecting live and earth. Now of course we do not know why it shorted, it is extremely unlikely that it did it all on its own.[/quote] An RCD fitted to that type of filter can sometimes nuciance trip as there will be earth leakage through the capacitors under usual working conditions. Normally it wouldn't be a problem, but when multiple devices are plugged in to it each with their own filters this can lead to high earth leakage currents. Often people will just take the RCD out without checking further for a real fault. Some types of equipment just have high leakage currents and cause problems when using RCDs, washing machines and fridges can play havoc with them. I am surpised that the fault current was still low enough not blow the fuse. If you do get a frequenly tripping RCD, use it to determine which bit of kit is causing the trip, by plugging each bit of kit into in turn until you find the offending article. Don't use the offending article until someone who knows what they are doing has checked it out. Shocks are an occupational hazzard to me, but luckily I've only had 2 'cup of tea' shocks in 15 years. That smell of your own burning flesh and feeling of galloping horses on you chest are not pleasant. I had an interesting gig where we were late on and the dep keyboard players amp kept cutting out. He had to keep his foot on the mains plug and everytime he moved his foot it cut out. We were then further delayed while I rewired all four of his mains plugs. After fixing the one that was showing problems I thought it wise to check the others and found they were all in as bad condition. Keep music Live not LIVE..... Edited August 1, 2009 by TimR Quote
RAY AGAINST THE MACHINE Posted August 1, 2009 Posted August 1, 2009 [quote name='stylonpilson' post='307583' date='Oct 16 2008, 08:34 AM']Scary stuff. Glad you're okay. S.P.[/quote] +1 Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.