Transfer Switch
What is the cheapest, most compact, simplest transfer switch I can buy? It only has to switch 120V, 15 amps max.
Forum Discussion
The neutral should be switched because of neutral/ground bonding concerns and the possibility of reverse polarity power sources and so forth. If the transfer is between a built-in generator and shore power, the generator will have neutral and ground bonded, but the RV should not have them bonded for the shore power connection, hence the need to switch the neutral. With some inverters, grounding either of the output terminals (to the negative DC input, which is generally also the chassis ground) will let out the magic smoke, so it's necessary to switch the neutral there as well. That leaves precious few cases where it's not necessary or at least highly advisable.
That being said, transferring power does not require switching the neutral in the most general case; there's no way to backfeed power (or feed power) through an open circuit, such as there would be if the hot were disconnected. There's an analogous situation to a common neutral shared by two different power sources in the two 12V systems of motorhomes: the chassis ground is the neutral for both the house and the chassis systems, and they don't interact with each other unless otherwise interconnected.
As a practical matter, switch the neutral; it's neither particularly hard nor particularly expensive to do so, and never incorrect.
That being said, transferring power does not require switching the neutral in the most general case; there's no way to backfeed power (or feed power) through an open circuit, such as there would be if the hot were disconnected. There's an analogous situation to a common neutral shared by two different power sources in the two 12V systems of motorhomes: the chassis ground is the neutral for both the house and the chassis systems, and they don't interact with each other unless otherwise interconnected.
As a practical matter, switch the neutral; it's neither particularly hard nor particularly expensive to do so, and never incorrect.
