Will hot/live go into NO and neutral into COM, to switch over 200v? Can someone explain please. I saw in some places it says natural into NO but what into com?

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    \$\begingroup\$ Depends. Are you trying to blow the fuse/breaker, or run electronic equipment? \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 29 '14 at 14:04
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    \$\begingroup\$ Hell no - that'll cause an instant short circuit, melted wires, fires, and blown fuses. Live goes into COM, and "switched live" comes out of NO - or the other way around, it doesn't matter. Neutral stays well away from the relay. \$\endgroup\$ – Majenko Oct 29 '14 at 14:04
  • \$\begingroup\$ @IgnacioVazquez-Abrams pretty sure I'm trying to run a component. \$\endgroup\$ – dan14941 Oct 29 '14 at 14:07
  • \$\begingroup\$ Then your component has to be somewhere in the circuit. \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 29 '14 at 14:08
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    \$\begingroup\$ It always worries the hell out of me when someone obviously lacking in basic electrical knowledge is messing around with mains. Professionals exist so that novices don't kill themselves and all those around them with dodgy wiring. \$\endgroup\$ – Majenko Oct 29 '14 at 14:19

A relay is just a switch - just like a light switch. It interrupts or connects the connection of LIVE (or "hot") to your device. Neutral remains connected direct to your device at all times.


simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Should I put electrical tape over the NC part of the relay? \$\endgroup\$ – dan14941 Oct 29 '14 at 14:13
  • \$\begingroup\$ I don't know. What is your relay? How is it mounted? What connections are you using? \$\endgroup\$ – Majenko Oct 29 '14 at 14:13
  • \$\begingroup\$ So far it's not mounted or connected cuz I didn't want to start a fire but I think I'll just put some tape i case. \$\endgroup\$ – dan14941 Oct 29 '14 at 14:16
  • \$\begingroup\$ Please post an image of your relay, and describe how you think you are going to attach the wires to it. \$\endgroup\$ – Majenko Oct 29 '14 at 14:17
  • \$\begingroup\$ If you connect the COM terminal to hot/live, then one or the other terminal will always be live. Which it is depends on whether the coil is powered or not. If you like, you can use this to run a small light to tell you that the load is off. \$\endgroup\$ – AaronD Oct 29 '14 at 14:20

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