In article ,
Scott Lurndal wrote:
When wire is referred to with a hyphen (e.g. 12-3), that means that
there are three AWG12 conductors encased in an outer jacket. Typically,
such cables are type "NM" (non-metallic sheathed) or "UF" (underground
feeder). w/G adds a non-jacketed conductor in the outer jacket that is
designated the grounding conductor. Most XX-3 w/g cables include red,
black, white and unjacketed conductors.

THHN is a wire "type" code used for single conductors that are routed
typically through some form of chase (electrometallic tubing (EMT) or
nonmetallic tubing, wiremold raceway, etc.).

THHN may not be used without an enclosing raceway of some form (note
that if your light fixtures are mounted end-to-end and there is a nipple
or length of EMT connecting them, then the fixtures themselves become a
raceway and THHN is allowed from the head fixture through the rest in
the row).

Thanks for the clarification. Sitting here in the UK I'd been wondering
what all your american abbreviations meant :-)

--
Stuart Winsor

Midland RISC OS show - Sat July 9th 2011