50 Amp CW Surge Protector Question ?

[jpf]

We have the 50 Amp Surge Guard exterior protector we generally use with the 3400.
I have occasionally used 30 amp with the up front 30 to 50 adapter when that was all that was available.
My question is; can anyone shed some light on whether the 50 amp surge protector can be used on a 30 amp rig ??
ie; plugged into 50 amp power at the pedastal, through the surge protector, and stepped down by a 50 to 30 adapter to a 30 amp cord to a 30 amp rated trailer ?

Thanks for any help with this....

jp