… before anyone asks i am more than qualified to answer this have years of experince as a sparky and network engineer.
Sorry, but your statements demonstrate that you are
NOT qualified to offer advice. Clearly you are one of those sparkies that is the bane of my life - the ones that
THINK they know how to do networking because "it's just more wires".
One of the worst things I get to do in the day job is "work with the sparky" installing a network. Sometimes they provide the containment (compartmentalised dado trunking for example) and I provide the cable and terminate it, sometimes they pull all the cable and I terminate it, sometimes they've terminated one end and I do the other. I did get to know one sparky well who I was happy with (but then he closed up shop and went abroad), but in general I "dislike" working with sparkies like this as far too often they demonstrate attitudes like yours and aren't prepared to learn.
On one job I came close to telling the customer that I was leaving site unless the sparkies stopped and ripped out all the data cable they'd pulled in (and I'd then install cable properly) such was the way they were treating it (they didn't treat the power cabling any better, and it was sub-freezing temperature).
rj45 cat5 uses only wires pins 1,2,3 and 6 for all speeds if you are referring to gigabit then most infrastructures dont have a backbone to support full gigabit it is for servers and fibreoptic networks.
Three statements, 0/3 for correctness. Like I say, stick to the electrics unless you are prepared to learn even some basics about networking. Bet you can't come up with a sub-gigabit network that uses all four pairs ? Or just two pairs but not 1&2,3&6 ?
The reason structured cabling conects all 4 pairs regardless of what it's being used for
now is precisely to avoid the problems that came up frequently in the past when each type of networking used it's own cabling standard. If you connect all 4 pairs (and for good measure,
TEST the installation properly) then the user doesn't have to guess now what he might want next year, or the year after that, or ...
Why would you run a extra wire when you can split off cat5, your speed will not be affected
Because speed
WILL be affected, and the cost of pulling in and terminating two cables instead of one is next to nothing in the grand scheme of things.