I love the idea of using a 5v micro controller to control my 110v 10 amp outlets. My only concern is the high voltage frying my board and burning my house down. Any thoughts?
One of the biggest issues for any 'mains control' is providing isolation between the 'Mains' voltage (high voltage) and the 'control' voltage (low voltage).
While the design appears to have optical isolation between the input and the relay coil, there is very little 'physical' isolation between the coil voltage (supply or common) and the controlling voltage pins. (single header)
Unless the board has a cut in the fibreglass around the contacts, under some circumstances the mains voltage can 'track over' to the relay coil pcb trace or control traces.
(433Mhz controlled mains outlet showing the cut in the pcb for mains isolation ..... photo by me)
Not only does this render the optocoupler useless, potentially you could have mains voltage present on a control wire (or supply or ground).
It's unlikely to trip or blow any circuit breakers as the controlling device is usually fed from a floating power supply.
These relay boards also lack an earth plane which can provide a current path for any 'fault currents' to trip the circuit breaker.
Often the pcb trace size is not adequate for 10A, which may simply cause the trace to part/blow or at worst cook the pcb (modern pcb designs should not support combustion ... but do you really know.)
So the reality is they are only suitable for controlling low voltages in their present configuration DESPITE THE RELAY RATING.
One of the biggest issues for any 'mains control' is providing isolation between the 'Mains' voltage (high voltage) and the 'control' voltage (low voltage).
While the design appears to have optical isolation between the input and the relay coil, there is very little 'physical' isolation between the coil voltage (supply or common) and the controlling voltage pins. (single header)
Unless the board has a cut in the fibreglass around the contacts, under some circumstances the mains voltage can 'track over' to the relay coil pcb trace or control traces.
(433Mhz controlled mains outlet showing the cut in the pcb for mains isolation ..... photo by me)
Not only does this render the optocoupler useless, potentially you could have mains voltage present on a control wire (or supply or ground).
It's unlikely to trip or blow any circuit breakers as the controlling device is usually fed from a floating power supply.
These relay boards also lack an earth plane which can provide a current path for any 'fault currents' to trip the circuit breaker.
Often the pcb trace size is not adequate for 10A, which may simply cause the trace to part/blow or at worst cook the pcb (modern pcb designs should not support combustion ... but do you really know.)
So the reality is they are only suitable for controlling low voltages in their present configuration DESPITE THE RELAY RATING.
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