900 watt Trans...

Discussion in 'Landscape Lighting' started by jbailey52, Jan 5, 2007.

  1. jbailey52

    jbailey52 LawnSite Bronze Member
    Posts: 1,089

    Can someone explain the use of an 'extra' common in the cast master series 900 trans? if each common still can only handle 300 watts, what is the use of the 4th common? I know it obviously has a good purpose, but im just not sure in what situation you would use it? Thanks!
     
  2. Allure

    Allure LawnSite Senior Member
    Posts: 426

    You could have 4 home run wires & hook each to it's own common so long as you don't exceed the transformers capacity.

    For example you might have 4 wire runs & each is 175 watts. You can't hook two to one common because it would exceed the max watts so you would use all 4 commons.
     
  3. jbailey52

    jbailey52 LawnSite Bronze Member
    Posts: 1,089

    Wait... you can have more then one home run in a common, as long as it doesnt exceed the 300 watts for that common and/or the 25 amp limit... remember they say "up to 7 #10 wires will fit"
     
  4. jbailey52

    jbailey52 LawnSite Bronze Member
    Posts: 1,089

    I know im missing it... but if the forth common doesnt expand the max watts.. I dont see whats its usefullness is.
     
  5. Allure

    Allure LawnSite Senior Member
    Posts: 426

    say you have 4 wire runs & each is 175 watts. you would have to use all 4 commons. You can't put two of those wires on the same common because that would be 350 watts which exceeds the commons 300 watt capacity.
     
  6. jbailey52

    jbailey52 LawnSite Bronze Member
    Posts: 1,089

    Ok Ok I see... That does make some sense... well it makes sense:)

    I was confused before because I thought you were saying that you could only have one cable per wire (wattage permitting) per common. For example having a 100 watt 10-2 and a 65 watt 10-2 and a 90 10-2 can all be on common one, permitted they are under 300 watts (Or the max of the terminal)
     
  7. Duekster

    Duekster LawnSite Fanatic
    from DFW, TX
    Posts: 7,961

    Yep, some loads allow you to de-rate the neutral but it is becoming more common not to allow derating because many over loads happen on the neutral. :nono:


    Low voltage and DC is something I should spend more time learning. :sleeping:
     

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