# Snubber maximum ratings

I'm developing a home automation system, and using a triac to power on/off some lights.

My problem is that lights from other rooms when switched on/off are producing noise/spikes and flashing the lights turned on by the automation (triac).

I added a snubber like this, and it is all good now. My point is how to calculate the ratings of the RC components.

The answer is "calculate the necessary power dissipation, and after that the RC", but considering that spikes are randomly and in rare situations I'm using a 0805 resistor and a 0805 capacitor.

My voltage is 220Vac. The resistor has Umax = 150V. I'm using it and it is working as expected. Aparently the lower voltage is not a problem for the spikes.

Can I desconsider the resistor Umax for spikes, and use it definatevly in my system? I'm assuming the RC will dissipate a very low energy.

• Why are you using such small components for the snubber? – ThreePhaseEel Dec 25 '18 at 23:10
• because I want a small device as possible – BrunoAraujo Dec 25 '18 at 23:18
• Please be smart and use 2 resistors in series for a 300V rating. That Vmax limit is not a joke. A professional job would even have slot cuts under the middle of each resistor to avoid creapage currents on the surface of the board. One arc across one resistor and you have a fire hazard. If the capacitor has at least a 500V rating then the fire hazard is very small. – Sparky256 Dec 26 '18 at 4:04