Originally Posted by distoga
Code states you should never run more load than 80% of what a cable is rated for (ie, if it's 14 guage at 120v you shouldn't run a full 1800 watts but instead no more than 1440 watts.
I personally like a little extra headroom if possible because: 1) wire heating & cooling in vast amounts over 50+ years will cause fatigue in the metal and casing. 2) a heated wire to it's rated level will have more resistance and could /theoretically/ alter performance of equipment running off it. 3) if you ever need to pull wire again (say you want to add more equipment or a 220 volt subs and need another circuit) or you need to modify something, having some space/ability to do that can be helpful. With all these added up, having conduit and giving the wiring a little extra buffer doesn't hurt and costs just a few dollars and 10 minutes if that. Wishing you had some headroom for future use I've found is worth its weight in gold, so imho I'd go past code and have the flexibility that could really come in handy later.
I'm not sure, however you may be referring to a breaker's rating of 80%, or conduit fill de-rating.
This was what puzzled me;
make sure your conduit lets the wire breath a little.
Regardless, one should always dedicate each receptacle, thereby allowing the ultimate flexibility down the road. Never daisy chain, always bring each one to the nearest JB, then if needs change, it's easy as pie. I prefer up-sized, dedicated and isolated home runs. Thus, the ultimate in flexibility.
wire heating & cooling in vast amounts over 50+ years will cause fatigue in the metal and casing
No offense, however this is a non-issue if the installation is correctly performed. With aluminum usage in the 70s, expansion and contraction/dis-similar metals became an issue. With contemporary copper wiring, either solid or stranded, this is no longer a concern.
Wishing you had some headroom for future use I've found is worth its weight in gold, so imho I'd go past code and have the flexibility that could really come in handy later
You're absolutely correct. The NEC is a minimum standard, not an installation guideline. My ample A/V circuits are dedicated, isolated, and over-sized