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Discussion Starter · #1 ·
Hey everybody!! I have a quick question, I want control a 110 volt strobe light with the Arduino relay shield. The relays are rated for 110volt 3 amp so that should not be a problem. My question is does it matter which wire on the power cord to the strobe I cut and run to the relay?? I'm guessing it doesn't since either will break the circuit but I want to be sure before I wire it up!! The circuit will be covered by a tombstone so there is no chance of anyone accidentally touching the wiring (except me!!). Thanks for your help!! HH
 

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You should switch (cut) the hot wire. If the plug is polarized, which means that one blade is wider than the other, the hot wire will be connected to the narrow blade.
 

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Really it does matter due to the fact that you want the power to switch on and off not the neutral. You could pick up a common neutral and get shocked because there is power at the prop. In DC it is common to switch the negative lead as to prevent welding of the contacts of the relay.
 

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When it comes to AC line voltage, it's never a good idea to assume that any neutral wire is safe to touch. You should ALWAYS treat every wire like it's hot, that's the safest practice and a very good habit to get into.
 

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I agree my point, is the power wire should be switched and not the neutral. If you check the light switches in your home you should find they switch the power and not the neutral. After all a relay is just a switch.
 

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Discussion Starter · #7 ·
Hey everybody!! Thanks for the responses!! The plug on the strobe light is polarized so I will be switching the hot wire!! i guess if you have something older without a polarized plug it would just be hit or miss!! I used to use some of my grandfathers old power tools that had the metal housings and two prong non polarized plugs!! Those things sure did make me nervous!! Lol!! Thanks again!! HH
 

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The reason for switching the hot wire in homes and buildings is consistency. Switching a fixture off allows you to work on the fixture or equipment with the power cut. That being said, it's never a good idea to assume anything when it comes to line voltage. Assumptions with line voltage can kill you. For the relay/prop application, again, really doesn't matter which line is cut, your props are not part of your house wiring.
 

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Well I would like to see what would happen if you switched the neutral using a relay and grabbed hold of the hot wire. I bet you would become your own prop...........
 

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I would have to agree with bfjou812, electrically it makes no difference which wire you attach to the relay, it will work. However, from a safety standpoint it makes a big difference. If you switch the neutral you are left with the situation of having a fully energized hot leg in your prop. If you touch that wire while the prop is plugged in you (providing a great path to ground) will receive a nasty and, in some cases fatal electrical shock. Remember it only takes 0.1 amps of AC current through your heart to cause the heart to go into fibrillation. (A state in which the heart no longer rhythmically contracts pumping blood but, for lack of a better explanation twitches).
 

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Well I would like to see what would happen if you switched the neutral using a relay and grabbed hold of the hot wire. I bet you would become your own prop...........
Why on earth would you grab ANY bare wire with the prop connected to 110vac?
 

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Apparently you're missing the whole point. I don't know your profession , or your experience. I do know what I was taught , and you do not switch the neutral on 110VAC circuit due to potential hazards. I'm not going to continue this due to the fact there is some sketchy information given here. Just for the record , I usually agree with a lot of your suggestions J-Man. I'm not trying to start SHI# STORM here..............
 

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I never looked at this discussion as a s*** storm. If this was house wiring I completely agree, as I mentioned. But this is not wiring connected to any house circuits. As another example, almost all outdoor light strings have a non-polarized plug, depending on which way you plug it in, either wire could be hot. So if you had a light string come apart and it was plugged in would you grab the bare wire?
BTW, just for the record, I was a commercial HVAC technician for 37 years. I worked with high voltage equipment on a daily basis. Number one rule, you never assume anything when working with line voltage, you use a meter first because you never know what someone else has done and you never trust any switch or disconnect.
 

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Hey everybody!! I have a quick question, I want control a 110 volt strobe light with the Arduino relay shield. The relays are rated for 110volt 3 amp so that should not be a problem. My question is does it matter which wire on the power cord to the strobe I cut and run to the relay?? I'm guessing it doesn't since either will break the circuit but I want to be sure before I wire it up!! The circuit will be covered by a tombstone so there is no chance of anyone accidentally touching the wiring (except me!!). Thanks for your help!! HH
I wouldn't cut the wire on my strobe at all. Just make an outlet box and switch that instead.
 

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Discussion Starter · #15 ·
Hey Bosco!! Good idea!! That may be what I will do!! If I have enough room!! Everything is mounted inside the tombstone so I am kind of limited on space!!
 
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