I have a query regarding connection between instrument and junction box.
With my experience till now i have been using till now single pair cable to connect between instrument and junction box for connecting conventional type instruments

But now in one of the Pre Bid Engineering jobs i am doing, client has specified 2 X 2 X 1.13mm cable to connect between instrument and junction box for connecting conventional type instruments

I cannot understand the reason behind this for using 2 pair cable!
If i go ahead with 2 pair cable...i am a bit confused to follow same spare philosophy even at multi pair cables side!

Can anyone clear my doubt please.

 

perhaps the end user wants some spares.

--
Bob

 

I cannot see any point in installing 2 pair cable for a two wire transmitter. In a well design system the cable runs from transmitters should be 50 - 100m maximum. Any damaged cable could then be easily removed and replaced. Personally I have not seen single pairs damaged except for fire damaged cables which were then easily replaced.

 

Since the labor involved usually costs more than the wire, I routinely pull in spares, especially on difficult runs. It can save quite a bit of downtime and is really handy when someone wants just one more feature. I have yet to regret it.

Regards
cww