1. #1
    Hello guys,

    I have a small mill and the power supply was so bad to the workshop last timethat I used it that even my grinder kept dimming the lights and the whole lotkept tripping the whole workshop. At that point due to fear of damaging themachine I un-plugged it and left it.

    Now I have a new supply to the workshop I am rewiring it.I have heard a lot on here about electrical noise and am concerned, this my situation.My PC for the machine is under the machine mounted to the PC housing is a 4-waysurge protection extension lead which I plug the control box into, the PC and the monitor. Thecontrol box it right next the machine and the monitor, keyboard on top of thecontrol box. What I would like to understand is if I am risk of power supplycables outside control box causing a noise issue. Some of you reading this may wellbe having a good laugh at this point but I do not know the firstthing about electrical noise!
    As always any help will be appreciated

  2. #2
    Steve we need more information - isn't always the way!

    How is your workshop fed power?
    Is it from one 'way' on your house 'consumer unit' ?
    If so what is the fuse there rated at,
    What size (in terms of copper cross sectional area) is the cable to the workshop
    How long is it?
    When this cable arrives at the workshop is it terminated in a smaller consumer unit?

    I assume (dangerous!) that you have a separate lighting and power circuit - is the power a radial circuit or is it a ring main?

    How are you providing an earth? Are you 'exporting' an earth from the house or do you have a ground spike at the workshop?

    To keep your mains 'clean' you need to avoid heavy loads switching on and off being associated with the circuit you are concerned about. Frequently causes of electrical noise in a domestic situation are things with motors, as the motor shoves spikes onto the mains at start up. So washing machines, dish washers, fridges, freezers can all be troublesome.

    Let us know a bit more about the wiring so a more informed comment can be made.

  3. #3
    Hello Andrew
    Many thanksfor such a detailed reply.
    I will tryand tell you what if think we need here.
    We have a100amp overhead supply into the house PME supply. The work shop in question isvery small only 20ft x 8ft on the consumer unit we have a 50amp MCB for thesmall workshop going into that we have a 3 core 10mm2 SWA cable going 70meters, at the workshop end is a 6-way consumer unit. I only need a couple ofsockets. I have a twin socket (socket 1 on a 20amp MCB) that I was thinking ofkeeping for the CNC, plugging the 4-way surge protection lead into it and then puttingthe monitor, PC and the control box into the extension lead. I only have onstrip light with a plug on the end that I was going to plug into the secondtwin socket on its own MCB. There is no ground spike at the house or workshopwe understood the PME supply to be sufficient I am not sure only going on whatthe electrician told me. The workshop is a metal container and I have an earthspike on the shelf doing nothing, if need be I could bang it in the ground. Ifso would I put the cable into the consumer unit or just fix it to the shippingcontainer itself? Perhaps I am heading in the right direction or doing a no no!

    Many thanks


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