My 2nd-year instructor went over this one in class...
The intent is to avoid the male-PVC/female-metal construction because the male adapter threads are prone to breaking off - often due to thermal expansion or impact on the installation.
Using a female PVC adapter and a chase nipple (short metal conduit with both ends threaded) makes for a sound installation.
This applies mainly to explosion-proof and cast-aluminum FS boxes since they have female threaded openings.
[This message has been edited by u2slow (edited 09-19-2003).]
