I have seen plenty of SMPS with inputs labeled L, N, and E/GND, yet they are designed to run on American style 240VAC (ie fed by two hot wires, both 120VAC from ground). I think more appropriate labeling would be L1 and L2, but that would confuse some people wiring in a hot and neutral.

When you consider how easy a product built with this supply could get powered with the N terminal connected to a hot line (240V circuit, incorrect cord or outlet wiring, etc.), it would almost be negligent to not tolerate that condition. By designing it such, the manufacturer reduces its liability and offers a more flexible product.

I have seen plenty of SMPS with inputs labeled L, N, and E/GND, yet they are designed to run on American style 240VAC (ie fed by two hot wires, both 120VAC from ground). I think more appropriate labeling would be L1 and L2, but that would confuse some people wiring in a hot and neutral.

When you consider how easy a product built with this supply could get powered with the N terminal connected to a hot line (240V circuit, incorrect cord or outlet wiring, etc.), it would almost be negligent to not tolerate that condition. By designing it such, the manufacturer reduces its liability and offers a more flexible product.

One possibility why the RTN is connected to E is to protect the isolation from ESD. That can be inconvenient for some applications. There are plenty of supplies available that float.

I have seen plenty of SMPS with inputs labeled L, N, and E/GND, yet have been designed to run on American style 240VAC (ie fed by two hot wires, both 120VAC from ground). I think more appropriate labeling would be L1 and L2, but that would confuse some people wiring in a hot and neutral.

I have seen plenty of SMPS with inputs labeled L, N, and E/GND, yet they are designed to run on American style 240VAC (ie fed by two hot wires, both 120VAC from ground). I think more appropriate labeling would be L1 and L2, but that would confuse some people wiring in a hot and neutral.

When you consider how easy a product built with this supply could get powered with the N terminal connected to a hot line (240V circuit, incorrect cord or outlet wiring, etc.), it would almost be negligent to not tolerate that condition. By designing it such, the manufacturer reduces its liability and offers a more flexible product.