I have a portable 2500 watt generator for use when we have hurricane induced outages. It has a 110 or 220 outlet choice. In the past I used an extension cord and the standard outlet to power a refrigerator and maybe a radio or lamp. The house we bought recently has a generator transfer switch designed to power a few selected circuits that is "powered" by a 30 amp 4 prong connector. the Generator output is a 4 prong - 20 amp connection. The generator came with a plug to use with it. Can I safely use that plug mounted on a heavy duty cord that interfaces with a 30 amp rated, 4 prong female plug? Thanks in advance for your evaluations!