Wiring for a 100 Amp Mobile Cart

Discussion in 'Electrical Forum discussion & Blog' started by VP Coffee, Apr 21, 2011.

  1. VP Coffee

    VP Coffee New Member

    Messages:
    3
    Location:
    North Carolina
    Hey All,
    First off, I have no intention of doing a lick of this work myself! I'm just involved with a project and I'm curious about how this is going to get done.
    We're installing a couple pieces of equipment on a mobile cart in a museum. A 220, 30 Amp espresso machine, and a 120/208, 30 Amp Coffee Brewer.

    The cart has a couple other miscellaneous pieces of equipment and they all lead back to a 100 Amp panel in the cart.

    The cart needs to plug into a receptacle in order to receive power...
    I've seen 100 Amp cord caps and receptacles, but I'm curious as to what kind of wiring is going to have to be pulled for the receptacle!? Currently there are two single gang boxes at the location, but they have at the most, 10 gauge solid copper wire in there.
    Is it true that a 100 Amp receptacle will need #2 Wire? Is this going to be a nightmare for the museum to get that size wire pulled through the existing conduit back to the main panel?

    Any discussion would be appreciated. I learn a lot from the back and forth on these forums and appreciate it.

    Thanks,

    Nick
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    Welcome to the forum

    You have two different voltages, one 240 volt 30 amp and one 208 volt 30 amp meaning that you will have two cords which is not allowed.

    For the branch circuit number 2 aluminum is not large enough unless the calculated load is 90 amps or less.
    If using copper then number three would be what is need if the calculated load is more than 85 amps.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    A new 100 amp 240 load is quite an addition....have you checked to see if the panel will support that additional load? And yes, I think # 2 is probably what you need. Our electricians wil give you better info on that soon.
  4. VP Coffee

    VP Coffee New Member

    Messages:
    3
    Location:
    North Carolina
    Maybe while we're at it, someone can help me properly verbalize the difference between 220, and 120/208
    The 220 is a two hots and a ground appliance, and the 120/208 is two hots, and a ground, and a neutral (L6-30 bs L14-30). Why do I always have a hard time getting electricians to understand what I'm talking about? Is there a different terminology I should use?
    And in regards to the supply, I sure hope they're able to accommodate! This is a new construction and they were informed a long time ago. Problem is, the cart wasn't around and sometimes specs just aren't enough.
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    220 or 240 will come from a delta transformer and 208 will come from a wye transformer.
    208 will be 120 per leg to neutral and 240 will be 120 to neutral on two legs and 208 on the high leg
    The appliance will mandate if a neutral is needed in either a 240 volt or 208 circuit. You and God only knows what you are talking about with (L6-30 bs L14-30).

    Maybe so
    You said in your first post that both of these appliances goes to one 100 amp panel. If this is true then either the 240 or the 208 voltage will be used not both.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,534
    Location:
    Cave Creek, Arizona
    Normally a system has either 208 or 240, but not BOTH. In most cases the appliances can run on whichever you have, but the performance may be different depending on the appliance and which power you have. The wire size to the outlet will be determined by the amp load on the panel, and the circuit breaker feeding it, and NOT necessarily the main breaker in on your "cart". Is the coffee brewer 208 OR 120, or does it have a 208 heater and 120 v. control circuit? How many wire connections does it have? Two or three plus the ground?
  7. drick

    drick In the Trades

    Messages:
    392
  8. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    I should have known that but for some reason my mind went to line 6 30 amp and line 14 30 amps.

    Thanks for the heads up
  9. VP Coffee

    VP Coffee New Member

    Messages:
    3
    Location:
    North Carolina
    I was wondering if God was going to chime in on that...

    So when I'm dealing with espresso machines, as a general rule, they are Italian made products. No neutral. Often they are field wireable for single, or triple phase. So when designating to an electrician the power requirements, I would request a 30 amp, 208 receptacle for single phase, and a 30 amp 240 for triple?

    The brewers are typically American made and are also often field wireable for single or triple phase. The control circuit is 110, requiring a neutral... So. 30 amp, 120/208 or, 30 amp 120/240?

    I usually just indicate how many wires I need.
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    If all the appliances are wired into one 100 amp panel on the cart then there will be only one voltage of either 208 or 240 but it will not be both.

    There is one voltage of 208/120 wye (pronounced “Y”) which will have a center tap neutral point and another voltage of 240/120 delta which will have the center of one winding tapped for the neutral point.

    These are two complete and different voltages and will not be mixed in the same panel.

    Each appliance will have a nameplate that designates the voltage, amps, and frequency of that appliance. If you have one appliance that requires 208 volts and another that requires 240 volts then the cart will require two different feeds to supply these appliances.

    To operate a 208 appliance on 240 volts the appliance will not last very long. To operate a 240 appliance on 208 and the appliance will not last very long.

    The requirement of a neutral will not mandate the voltage requirement of an appliance. An appliance can be either a three wire (meaning no neutral) or a four wire (meaning a neutral is required) 208 or 240 volt appliance.


    EDITED TO ADD:

    Click on jwelectric on the left side of the page and the click on private message. Send me a PM to where in NC you are located and if yor are within an hours drive of Asheboro I will be glad to come help you with your problem for free.
    Last edited: Apr 22, 2011
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