Is it good practice to tie the conductors for each circuit together?
Singles in trunking
- Thread starter ban-all-sheds
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Having worked where they were not my gut feeling is yes. But the whole idea of bunching cables has a load of pros and cons.
In auto electrics where something has burn out one notices it only seems to burn out away from the harness and the harness tightly wrapped seem to conduct the heat away better than when the wire is in free air.
But in conduit the reverse seems to be true I will assume because of two fractures.
1) They are not tightly bunched so there is not the conduction found with a harness.
2) All cables tend to be used not just a few. Where in the motor vehicle the time each circuit is used is very short.
I had many an argument where I would prefer tray work and SWA cables as there don't tend to effect each other in the same way and easier to make drops. The guy I worked with liked trunking and conduit and said the conduit did a better job. However when fitters moved the machine 6 inches I know which was easier to move.
We would sit there and about every 3 foot tape the cores together. But come back in a years time and there always seemed to be another cable threaded between them. But no one ever owned up to it! So to move them the tape would all have to be removed before we could pull them back.
There was also a tendency to assume three wires taped together were part of same circuit. However on a number of times this proved not to be the case.
So the tape together or not tape together really depends on the foreman and how he runs the job. I hate trunking as the amount of voltage induced (or capacitance) in the wires without being connected to anything is too high to be safely workable and so one has to turn off the whole system to just terminate one set of wires. And of course any unused have to be earth bonded.
Give me SWA or SY on tray any day.
In auto electrics where something has burn out one notices it only seems to burn out away from the harness and the harness tightly wrapped seem to conduct the heat away better than when the wire is in free air.
But in conduit the reverse seems to be true I will assume because of two fractures.
1) They are not tightly bunched so there is not the conduction found with a harness.
2) All cables tend to be used not just a few. Where in the motor vehicle the time each circuit is used is very short.
I had many an argument where I would prefer tray work and SWA cables as there don't tend to effect each other in the same way and easier to make drops. The guy I worked with liked trunking and conduit and said the conduit did a better job. However when fitters moved the machine 6 inches I know which was easier to move.
We would sit there and about every 3 foot tape the cores together. But come back in a years time and there always seemed to be another cable threaded between them. But no one ever owned up to it! So to move them the tape would all have to be removed before we could pull them back.
There was also a tendency to assume three wires taped together were part of same circuit. However on a number of times this proved not to be the case.
So the tape together or not tape together really depends on the foreman and how he runs the job. I hate trunking as the amount of voltage induced (or capacitance) in the wires without being connected to anything is too high to be safely workable and so one has to turn off the whole system to just terminate one set of wires. And of course any unused have to be earth bonded.
Give me SWA or SY on tray any day.
T
tonyelectric
Hi BAS
I was at a school in their DT shop yesterday and had to pull a trio of wires back through the trunking to move a lathe isolator about 10ft along, all the sets of 3 lives feeding each isolator had been taped every 2 ft or so, which I thought was neat until I started pulling it back and they crossed and stuck solid. In the end had to pull off 10ft+ of very well painted on trunking lid, then had a similar difficulty putting in an earth for the new isolator position, so I would say no for the sake of the future user.
You could use numbered tapes or sleeves to identify sets
I was at a school in their DT shop yesterday and had to pull a trio of wires back through the trunking to move a lathe isolator about 10ft along, all the sets of 3 lives feeding each isolator had been taped every 2 ft or so, which I thought was neat until I started pulling it back and they crossed and stuck solid. In the end had to pull off 10ft+ of very well painted on trunking lid, then had a similar difficulty putting in an earth for the new isolator position, so I would say no for the sake of the future user.
You could use numbered tapes or sleeves to identify sets
These days it is considered best to just lay them in.
In the past they used to be taped.
I have done it both ways.
These days I don't bother.
In the past they used to be taped.
I have done it both ways.
These days I don't bother.
As implied above it's ok taping/tieing them together as long as it is done before the cables go in to ensure that there are no tangles with other circuit cables which can be a pain.
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