Flame detector wiring connection

[shkoko2000]

Dear all,
In our site, we have 12 flame detectors(IR type) connected directly to plc (direct wire for each detector).we will add another 12.
My question is if we connected them to junction box and then connect them to plc right or wrong. If there a standard determine how to connect the wire (directly or through junction box) and what is this standard.

 

[Bit_Bucket_07]

Insufficient information to offer an opinion.

 

[shkoko2000]

Why? And what the additional information you need to give ur opinion

 

[Bit_Bucket_07]

What kind of flame detectors? What kind of PLC inputs?

If you're talking about discrete inputs from a flame detector relay, then terminating the wires in a junction box isn't a problem.

 

[shkoko2000]

The flame detector is IR 3112 general monitors.the plc card is digital input 1756-IB32.and if there a standard determine weather i connected it directly or to junction box.

 

[mocca-fixer]

Dear shkoko, from what I recall using a junction is not a problem, but be aware of the length of the wire. The signal can be lost if the travel distance is greater than 100m. Have a nice day!

 

[shkoko2000]

There is one from the existing flame that connected directly has distance over 400 m

 

[shkoko2000]

And working properly

 

[Bullzi]

Using Junction Boxes have there positives and negatives. What you do really depends on how you want the system to work.

The positives are you can change where the signal terminates easier. The transition from conduit to tray cable is easier with a JB.

The negatives: Longer cable runs. Most of the time this isn't a issue, especially for digital signals. Analog signals can be affected by the longer cable runs. Another issue is with more connections also comes more points of failure. Many times I have chased down a problem only to find a loose terminal in a JB that is causing all the problems.

 

[shkoko2000]

If there a standard related to use junction box

 

[Bullzi]

Not that I know of. That would more likely be a company standard.