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Wire Voltage Rating

Discussion in 'Electronic Design' started by Bobd, Jul 18, 2005.

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  1. Bobd

    Bobd Guest

    We recently caught a purchasing error in production. 300V wire was
    accidently purchased instead of the specified 600V rated wire. This
    wire is used to connect a 3 phase 480V motor to a combination starter.

    After this occurred I tried to figure worst case scenario but am having
    trouble. If a single line voltage is 277 to neutral, is the 300 volt
    wire okay in this case?

    If line to line is 480V, wouldn't two 300V wires really be 600V
    protection from conductor to insulator (for line 1) to insulator to
    conductor (for line 2)?
  2. colin

    colin Guest

    277v is bit close for comfort isnt it, what is the maximum the line to earth
    can go to under fualt conditions ?
    ie floating nuetral, short from line to nuetral and or line not conected to
    source etc?

    I'm not familiar with practice regard to specifiying cable voltage ratings
    with regard to safety factor/derating for curent/temp/being enclosed etc.

    so I wouldnt be very happy to sign the aceptance.

    Colin =^.^=
  3. legg

    legg Guest

    This line of inquiry may be beside the point.

    What material does your UL file's constructional data sheet state is
    to be used?

    Similar UL wire styles with differing voltage listings differ usually
    in one significant physical feature - the thickness of the insulation
    layer. It may be acceptable to sleeve the erroneous material to meet
    constructional data statement wording - check with your liason officer
    for the file in question.

    This won't save you any money, but might allow deadlines to be met.

  4. John G

    John G Guest

    277 volts is the RMS line voltage not the Peak which is 277 x 1.414 =
    391, so your 300volt insulation is not satisfactory for one line to
    ground under good conditions.

    Sack the specifier and buy the correct wire, is the only good advice.
  5. Rich Grise

    Rich Grise Guest

    Nah, don't sack him - do the fix, and take the cost out of his
    paycheck. >;->

  6. keith

    keith Guest

    Oh, my! I thought 600V wire was required for 120V service. It seems
    someone unloaded stuff they couldn't sell. Well, just hook two wires in
    series. ;-)
  7. Bobd

    Bobd Guest

    I spoke to a UL person today. He told me 300V and 600V wire are tested
    the same if it has the AWM (Appliance Wire Manufacture - i believe)
    mark. Both are subjected to a 2000V dielectric test!
  8. legg

    legg Guest

    Is the UL person OKing the substitution?

  9. John G

    John G Guest

    If it is labelled 300 volts then thats the evidence that will be used
    against You when there is a fatality.
  10. Guest

    If there's any accident insurance & criminal justice will likely look at the
    rateing. Not that the cable happends to be the same as the 600V version.

    Useing it is like playing poker..
  11. Terry Given

    Terry Given Guest

    and thats really the only way to look at it.

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