II have about junction box and the nema 4x question

Can't understand the question in #1

#2; IP65 is not the same as NEMA 4X because:

a) The hose-down test requirements are not even close to the same. The NEMA 4 test is 100GPM of water at 60PSI from any direction. IPx5 is tested with the equivalent of a shower head at low pressure. IPx6 is brief submergence, so it is generally accepted that this should pass the NEMA 4 test, but even that is not guaranteed. Besides, "NEMA" means nothing any more. NEMA was never a testing authority, it was a set of voluntary guidelines and test procedures. But some time ago, UL adopted the NEMA test procedures and numbering system. UL, being an independent testing authority, is more stringent about the testing. So although many IEC manufacturers claim to have NEMA 4 when they have IP65, their UL files will often show only UL type 12, and that is the value that really counts.

b) The "X" in NEMA 4X is for corrosion resistance and lists a host of chemicals that it must be impervious to. IP65 does not address corrosion in a manner ever remotely similar. IP66, because of it's designation for use in "heavy seas" includes a test for salt corrsion that is equal to the NEMA 4X, but not specifically other corrosives. However, most IP66 rated products are non-metallic and made of the same materials as NEMA 4X, so everyone sort of accepts the likelihood of them passing.

"...products are non-metallic and made of the same materials as NEMA 4X,..."

Not all NEMA4X panels are non-metallic. You were correct in stating that the X designates non-corrosive, but that doesn't mean non-metallic. Actually, most of the NEMA4X panels I furnish are 304 stainless steel. I have furnished a few in aluminum, more in fiberglass but most stainless steel.