Neutral on the left (as you are facing the plug and the grounding pin is on the bottom) is normal here in the US. It's not uncommon (as in my house, built in 1972) for the electrician to install the outlets upside down with the grounding pin on the top. So without polarization it's good to check.
Your PSU will either work or not work - there's no harm in trying it. I believe that vendors (especially generic whitelabel vendors in China) may sometimes overstate their current capacity because they figure that nobody can possibly be using all that current and if they are, how are they going to know our PSU is to blame???
I have a Prusa i3 with a Magma hot end connected to RAMPS 1.4 electronics. I haven't measured current consumption but the heated bed is supposed to draw 11A at 12V and the nozzle heater should draw 6A. I started out with a generic 400W PSU that claimed to provide 20A on the 12V rail. I connected both the mainboard 12V and what is usually the "high current" 12V (from a 4-pin or 6-pin Molex connector with yellow and black wires) and everything worked ok but I could never reach the full temperature with both heated bed and nozzle, even after waiting an hour or more.
So yes, if you actually have a PSU that supplies 20A as stated you should be fine. If the manufacturer is lying about the capacity you may end up with insufficient current.
The Magma comes with a fan and if the fan is blowing directly on the nozzle, it may be nearly impossible to get higher temperatures, but after switching to an Antec Basiq 500W power supply I did not have any problems, and suddenly my time to heat the bed dropped from 30 minutes to 2 minutes. So I am quite positive the 400W power supply was simply not performing as rated.
In my opinion it's worth soldering after crimping particularly for heater connections. 2 square mm wire is approximately equivalent to AWG14 (1.63mm diameter) which should be sufficient (I'm using stranded AWG14 for my RAMPS to heated bed connection, which is probably overkill). That is also a commonly used gauge (per wire) for small appliances and PC power cords, so should be sufficient.
Your PSU will either work or not work - there's no harm in trying it. I believe that vendors (especially generic whitelabel vendors in China) may sometimes overstate their current capacity because they figure that nobody can possibly be using all that current and if they are, how are they going to know our PSU is to blame???
I have a Prusa i3 with a Magma hot end connected to RAMPS 1.4 electronics. I haven't measured current consumption but the heated bed is supposed to draw 11A at 12V and the nozzle heater should draw 6A. I started out with a generic 400W PSU that claimed to provide 20A on the 12V rail. I connected both the mainboard 12V and what is usually the "high current" 12V (from a 4-pin or 6-pin Molex connector with yellow and black wires) and everything worked ok but I could never reach the full temperature with both heated bed and nozzle, even after waiting an hour or more.
So yes, if you actually have a PSU that supplies 20A as stated you should be fine. If the manufacturer is lying about the capacity you may end up with insufficient current.
The Magma comes with a fan and if the fan is blowing directly on the nozzle, it may be nearly impossible to get higher temperatures, but after switching to an Antec Basiq 500W power supply I did not have any problems, and suddenly my time to heat the bed dropped from 30 minutes to 2 minutes. So I am quite positive the 400W power supply was simply not performing as rated.
In my opinion it's worth soldering after crimping particularly for heater connections. 2 square mm wire is approximately equivalent to AWG14 (1.63mm diameter) which should be sufficient (I'm using stranded AWG14 for my RAMPS to heated bed connection, which is probably overkill). That is also a commonly used gauge (per wire) for small appliances and PC power cords, so should be sufficient.