PARALLAX Power Supply ATS503 120/240V 50 Amp Transfer Switch

I replaced my 501 box with this one because a relay had failed and I could not find a replacement relay for the 501.It was very easy to install. So far so good with the 503 box.

Works fine but wiring not the same, had a hell of a fight. Totally different design from 501.

It does exactly what it was intended to do.The application was for a class a diesel motor home ... to transfer current from either 50 amp home power or 50 amp diesel generator power to be used within the motor home

Used on motorhome

I rarely write reviews but felt I had to in this case to warn others. I installed this transfer switch in my RV to switch between inverter and shore power. It worked great for a few days then stopped switching (stuck on shore side even if inverter power is present and shore is not). I called the manufacturer and after a few debugging steps they concluded the device was faulty and had to be replaced but they said that since I bought it from Amazon they would not honor the warranty. Amazon's great customer service took care of me but be aware that this device and the manufacturer support (for Amazon orders at least) seems unreliable.

I purchased this to replace an older 501 model. From what I could tell the 503 has the same footprint but beefier switches so hopefully it will be a better part. Only time will tell but it installed quickly and seems to be working great.

Bought this to replace an ATS501. This unit is bigger and all of the internal parts are much bigger and more robust. It is a much more heavy duty switch than the one it replaces. In a large motorhome this switch does the job!

When I received the ATS503 i noticed that one of the circuitry boards was not attached to it. So I reconnected it and installed it. But the item does not work. Hoping to send back for an exchange.