woz 44 #1 Posted October 8, 2016 hi, our house is fed with 3 phase it runs straight into 3x 25 amp wire fuses from there it goes to my old workshop.again to wire fuses..iv moved the workshop to a bigger shed..iv run a 6mm 5 core cable accros to the new shed from the 25 amp fuses in the house.....in the new shed iv used a 64 amp twist on/off switch then to a plastic box as described below 16A 5 pin socket 3P + N + E IP44 (no overload protection) 32A 5 pin socket 3P+N+E IP44 ( no overload protection) 4 Pole RCD 63A 30mA 2 Pole RCD 63A 30mA 2 x 16amp MCBs 2 x 240V 16A 3 pin Commando Industrial Socket IP44 (RCD and overload protected) Enclosure dimensions: H 240mm, W 190mm, D 150mm Dimensions with sockets: H 240mm W 300mm D 150mm. We can change sockets on request, please send us a message prior to buy. 400V3phase16A&32A 5 Pin RCD Industrial Socket +240V16A 3pin .Distribution board. my 300 amp butters mig/400 amp inverter stick and plasma all work fine no issues........ yesterday i bought a BIG horizontal 3 phase band saw,it was getting dark when i got home so unloaded it straight into the old shed on wire fuses,plugged it in and it worked great..today i managed to get the saw into the new shed, plugged it in and it just pops the rcd..i have turned the master switch to off on the band saw and it still trips the rcd...if i run the saw with our standby generator it works fine any ideas could well be a big help Share this post Link to post Share on other sites
Stormin 4,458 #2 Posted October 8, 2016 Has the pug got wet/damp over night? 1 Rocboni reacted to this Share this post Link to post Share on other sites
Rocboni 257 #3 Posted October 8, 2016 (edited) Must have an Earth fault, it will run off a generator fine as it has no RCD? Along with your old workshop? Does the bandsaw have a Neutral, I'm guessing a neutral to earth fault as live to earth would result in a bang! Try to isolate sectons of the circuit. Edited October 8, 2016 by Rocboni Share this post Link to post Share on other sites
woz 44 #4 Posted October 9, 2016 5 hours ago, Rocboni said: Must have an Earth fault, it will run off a generator fine as it has no RCD? Along with your old workshop? Does the bandsaw have a Neutral, I'm guessing a neutral to earth fault as live to earth would result in a bang! Try to isolate sectons of the circuit. your right..............i'll post a few pics tommororow...........its got a control panel/box and where the main power comes in above that where the power was distributed the negative had been piggy backed accross to the earth? it looks factory? i snipped the loop and it works fine...it has had a new power cable and plug fitted and im guessing the previous owner thought it was knackered and stuck it in the auction........3 phase scares me to death ......thanks for your replies chaps warwick 1 Rocboni reacted to this Share this post Link to post Share on other sites
meadowfield 1,900 #5 Posted October 9, 2016 Definitely earth leakage, is there a neutral in the wiring? Should just be three wires and and earth. Your incoming should bring neutral in as a tap from the transformer. my lathe is a 4 pin plug, of which one is earth. The motor is delta configuration and uses three wires. Any combination works, if the motor spins the wrong way then swap two. sounds like a simple wiring issue (hopefully) Share this post Link to post Share on other sites
Rocboni 257 #6 Posted October 9, 2016 There's no way that the earth should be connected to the neutral at the machine, (although your earth is basically your Neutral at the DNO cut out) this is what will be causing the tripping as the RCD will be seeing this. meadowfeild, Saw may require a Neutral for the control circuit if modern contractors ect are used. If just a straight DOL starter only 3 phase and earth. Share this post Link to post Share on other sites
Rocboni 257 #7 Posted October 9, 2016 15 hours ago, Stormin said: Has the pug got wet/damp over night? Leave the dog out did we? 1 Stormin reacted to this Share this post Link to post Share on other sites
Stormin 4,458 #8 Posted October 9, 2016 5 hours ago, Rocboni said: Leave the dog out did we? Share this post Link to post Share on other sites
woz 44 #9 Posted October 9, 2016 (edited) this is the bottom right of the control box where the power comes in...the blue (negative) which was looped to the earth, iv snipped the loop and taped it ,, the blue looped cable looks factory,was run up into the conduit and is in the same shrink wrap as the earth,,,could there be any reason that it has been wired like this?? Edited October 9, 2016 by woz Share this post Link to post Share on other sites
Rocboni 257 #10 Posted October 9, 2016 Fantastic bandsaw, the loop does look like original as it has the crimp ferrules, however it should never of had this, the only reason I can see is if some one wired it without a neutral supply and was pulling a reference to ground so that the control circuit works, an electrician would not do this, its a big no no! Very dodgy. I would suggest you snip the ferrules off, strip the cable and put it back into the DIN rail terminals, you stick a screwdriver into the square hole to release the clamp. Share this post Link to post Share on other sites
woz 44 #11 Posted October 9, 2016 (edited) ill do a propper job of removing the neg/earth loop..i wasnt sure about the wiring so just snipped it to try it...the farms on very dodgy old wiring so iv had to learn how to wire the shed etc.at the time.i really didnt see much point in hammering a 5ft earth rod through stoney ground......im glad titch nagged me about rcd's and earths now really Edited October 9, 2016 by woz Share this post Link to post Share on other sites
