Originally Posted by Hohenwald48
I don't know. Plugging a 15 amp cord into a 30 amp outlet sounds a lot like plugging a 30 amp cord into 50 amp outlet to me. But maybe not.
Not the same at all.
Plugging a 30 amp Travel Trailer into a 50 amp supply is safe. The modern TT power panel has a 30 amp main breaker. That means that the 30 amp cord to the TT can never be overloaded.
In power distribution there is a 10 foot tap rule for supplying power off a distribution bus. That rule allows a tap which is not sized for the main bus overcurrent protection to be used to supply a switch or breaker which has proper level of protection. The theory being that the tap conductors cannot be overloaded. I look at a 50 to 30 amp adapter for a TT with main breaker protection as being a similar situation.
Plugging an unprotected 30 amp cord into a 50 amp supply (not a TT situation) does have the danger of possible overload on the 30 amp rated cord. The 50 amp breaker would protect the 30 amp cord in the event of a dead short, but could allow long time overcurrent to overheat the cord.
A 15 amp cord fed by a 30 amp adapter does not have proper overcurrent protection. The small cord can easily be overloaded. The 30 amp protection allows 100% overload on the 15 amp cord. It also lacks GFCI protection as I mentioned in my previous post.