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Low Earth Orbit
Lighting & Electrical
Why An Open Neutral Kills 120V Devices
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<blockquote data-quote="Langston Holland" data-source="post: 58713" data-attributes="member: 171"><p>The Test</p><p></p><p><strong>The first one to answer the (18) questions correctly wins the circuit analyzer or ONE MILLION DOLLARS</strong>[SUP]*[/SUP]</p><p></p><p>Aleš, John and Mike are disqualified just because and my budget for shipping is about $20. <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile :)" data-smilie="1"data-shortname=":)" /></p><p></p><p><u>Assumptions</u>: (<a href="http://soundforums.net/lighting-electrical/4812-why-open-neutral-kills-120v-devices-post33409.html" target="_blank">refer to open neutral demonstration board schematic</a>).</p><p></p><p>B = Incandescent light bulbs rated at 120V, 25 watts. All are in working order and maintain constant resistance regardless of applied voltage.</p><p>TP = Test Point that will accept multimeter probe.</p><p>Switch closed = Circuit connected (solid line)</p><p>Switch open = Circuit broken (dashed line)</p><p>N = Neutral</p><p>L1 = 120V relative to N, 240V relative to L2.</p><p>L2 = 120V relative to N, 240V relative to L1.</p><p>The dash between like components means "through".</p><p>Each bulb means all (10) bulbs! <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile :)" data-smilie="1"data-shortname=":)" /></p><p></p><p><u>Concepts</u>:</p><p></p><p>Series means one after the other. The bulbs B5 and B6 are connected in series. If a bulb in series stops passing electricity, the other bulb turns off.</p><p></p><p>Parallel means each bulb is wired identically to the others. The (4) bulbs B7 - B10 are wired in parallel. If a bulb in parallel stops passing electricity, the others still work.</p><p></p><p><u>Relevant portions of Ohm's Law</u>: (once R is known, solve for I, then E)</p><p></p><p>Resistance = R = E^2/W</p><p>Current = I = E/R</p><p>Voltage = E = IR</p><p></p><p><u>Questions</u>:</p><p></p><ol> <li data-xf-list-type="ol">What is the resistance of a single bulb?</li> <li data-xf-list-type="ol">What is the series resistance of B5 and B6?</li> <li data-xf-list-type="ol">What is the voltage between TP1 and TP3?</li> <li data-xf-list-type="ol">How much voltage does B5 see?</li> <li data-xf-list-type="ol">How much voltage does B6 see?</li> <li data-xf-list-type="ol">What is the parallel resistance of (2) bulbs?</li> <li data-xf-list-type="ol">What is the parallel resistance of (3) bulbs?</li> <li data-xf-list-type="ol">What is the parallel resistance of (4) bulbs?</li> <li data-xf-list-type="ol">With S1 - S5 closed, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 - S4 closed, S5 open, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 open, S2 - S4 closed, S5 open, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 - S2 open, S3 - S4 closed, S5 open, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 - S3 open, S4 closed, S5 open, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 - S4 open, S5 open, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 open, S2 - S4 closed, S5 closed, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 - S2 open, S3 - S4 closed, S5 closed, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 - S3 open, S4 closed, S5 closed, how much voltage does each bulb see?</li> <li data-xf-list-type="ol">With S1 - S4 open, S5 closed, how much voltage does each bulb see?</li> </ol><p></p><p>* At my discretion.</p></blockquote><p></p>
[QUOTE="Langston Holland, post: 58713, member: 171"] The Test [b]The first one to answer the (18) questions correctly wins the circuit analyzer or ONE MILLION DOLLARS[/b][SUP]*[/SUP] Aleš, John and Mike are disqualified just because and my budget for shipping is about $20. :) [u]Assumptions[/u]: ([url=http://soundforums.net/lighting-electrical/4812-why-open-neutral-kills-120v-devices-post33409.html]refer to open neutral demonstration board schematic[/url]). B = Incandescent light bulbs rated at 120V, 25 watts. All are in working order and maintain constant resistance regardless of applied voltage. TP = Test Point that will accept multimeter probe. Switch closed = Circuit connected (solid line) Switch open = Circuit broken (dashed line) N = Neutral L1 = 120V relative to N, 240V relative to L2. L2 = 120V relative to N, 240V relative to L1. The dash between like components means "through". Each bulb means all (10) bulbs! :) [u]Concepts[/u]: Series means one after the other. The bulbs B5 and B6 are connected in series. If a bulb in series stops passing electricity, the other bulb turns off. Parallel means each bulb is wired identically to the others. The (4) bulbs B7 - B10 are wired in parallel. If a bulb in parallel stops passing electricity, the others still work. [u]Relevant portions of Ohm's Law[/u]: (once R is known, solve for I, then E) Resistance = R = E^2/W Current = I = E/R Voltage = E = IR [u]Questions[/u]: [LIST=1] [*]What is the resistance of a single bulb? [*]What is the series resistance of B5 and B6? [*]What is the voltage between TP1 and TP3? [*]How much voltage does B5 see? [*]How much voltage does B6 see? [*]What is the parallel resistance of (2) bulbs? [*]What is the parallel resistance of (3) bulbs? [*]What is the parallel resistance of (4) bulbs? [*]With S1 - S5 closed, how much voltage does each bulb see? [*]With S1 - S4 closed, S5 open, how much voltage does each bulb see? [*]With S1 open, S2 - S4 closed, S5 open, how much voltage does each bulb see? [*]With S1 - S2 open, S3 - S4 closed, S5 open, how much voltage does each bulb see? [*]With S1 - S3 open, S4 closed, S5 open, how much voltage does each bulb see? [*]With S1 - S4 open, S5 open, how much voltage does each bulb see? [*]With S1 open, S2 - S4 closed, S5 closed, how much voltage does each bulb see? [*]With S1 - S2 open, S3 - S4 closed, S5 closed, how much voltage does each bulb see? [*]With S1 - S3 open, S4 closed, S5 closed, how much voltage does each bulb see? [*]With S1 - S4 open, S5 closed, how much voltage does each bulb see? [/LIST] * At my discretion. [/QUOTE]
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Why An Open Neutral Kills 120V Devices
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