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Thread: LUT-MLC - No Neutral

  1. #1

    LUT-MLC - No Neutral

    Hi-I've been poking around some of the threads trying to get a handle on the LUT-MLC placement - particularly in a setup where I don't have a neutral.

    I have 2 scenarios - easiest is PD-5S-DV-WH with an LED bulb that doesn't go 'off', but glows dimly (so I believe I need the shunt capacitor to absorb the trickle current).

    Reading the install instructions, it says to install the MLC between the neutral and the hot-switched cable. If I don't have a neutral, can I still use it? (so I have 2x black (1 hot, 1 switched) and the ground).

    I have exactly the same scenario installing a MSCL-OP153M digital dimmer with an LED downlight - so again, with no neutral I'm wondering if I can use the MLC to help.

    Thanks in advance for pointers/advice.

  2. #2
    Senior Member
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    There is a neutral in the circuit somewhere. You may have to install the MLC at the fixture.
    Convergence Technologies Raleigh, North Carolina
    www.convergenceusa.com

  3. #3
    Got it - that makes sense. And there was me hoping to have a clean white wire in the box :-)

    Just to make sure I understand the principle (not an electrician)

    -The inbound hot wire brings the AC from the panel into the switch
    -Mechanical switches would typically just break the circuit , and with an incandescent bulb there isn't enough power to light it up. So no problem.
    -With these digital switches combined with LED's, if there is insufficient minimal load (i.e. I dont have enough fixtures) to absorb the excess ‘trickle’ (that the switch uses to power its LED, radios etc), then this current passes through the switch, over the 'switched' wire , passing the current to the bulb (and hence the glow)
    -By installing the MLC between this outbound, switched wire and the neutral, it absorbs the low current into the shunt capacitor , and then dumps its out over the neutral line (instead of the fixture/bulb)

    And if I’m doing at the fixture, I’m just dumping the current later in the outbound circuit to the bulb. Got it. I think :-)

  4. #4
    Senior Member
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    2,587
    Mechanical switches completely cut off power to the load. There is no glowing because there is no power at all.

    The 'trickle' is used to power the electronics in switches/dimmers. This occurs regardless of how much load you have. This is why you should always pull the gap switch when changing bulbs, etc.

    If you don't meet the minimum load, electronic switches/dimmers can't turn themselves completely off. With LEDs or CFLs you may see a glow. It is also there with incandescent but probably not enough to be visible. The MLC electronically fools the switch into thinking the minimum load is there.

    So the next question is, "Why don't they incorporate the MLC into the switch/dimmer itself?" I have no idea.
    Convergence Technologies Raleigh, North Carolina
    www.convergenceusa.com

  5. #5
    Makes sense-thanks everyone!
    Presumably this is what the ‘supported bulbs’ do vs non supported (they either don’t light below a minimal current, or they have their own LUT-MLac built in)

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