There are pros and cons to each kind of switch, so you should explore each of these options when trying to decide which one works best for your needs. Automatic transfer switches are very convenient in that you do not have to be physically present to flip the switch if your main power source loses power. If you are away from home during an outage, your major appliances can keep running with no interference. In addition, an automatic switch will sense when it needs to switch power.
An automatic power transfer switch will power up the alternative generator when there is a brownout. However, if the intermittent power outages cease after a period of time, the power will not switch to the generator. With a manual switch, you have to switch the power from the main power source to standby. Manual switches are designed to prevent the two power sources from running simultaneously because this can be dangerous to both you and your equipment.
You can also get a combination automatic and manual switch. With this switch, you still get automatic functions of starting, shutting off, monitoring and activating the switch. However, other functions must be run manually. The benefit of any of these switches is that you do not need to run extension cords in and out of the building in order to power the generator. Using cords can be dangerous because they can be exposed to standing water or some other danger such as debris after a storm.
You can even use a power transfer switch with a portable generator. However, you are most likely to use a manual switch with a portable device. In fact, many homes still have a manual switch because automatic switches tend not to have some advanced monitoring features. It is important that you consider all the pros and cons of any kind of transfer switch before you decide which is right for you. You can then make sure it is compatible with the generator that best fits your needs so that you are never without power.

