Mixed voltages in cables

[Spudmiester]

Here's one chaps,

I was talking to a bloke the other day who claimed it was ok to have 415v AC and 24v DC running through the same cable (2.5,7 core) at the same time.
This was for a 3ph motor, with the 24v being for an early break control through a 4th pole in the isolator, and back to the contactor coil.
He has an NIC ticket on the job, so says its definitely ok.

Now, when I was at the water board, we had it drummed into us that this was a no no. They wouldnt even let us put mixed voltage cables in the same ducting.

All this was under the 16th edition by the way, and I want to know who is right, and has it changed under the 17th ?

Am hoping those with more regs know-how than me can help !

Will leave it with you , off for a curry and some beer !

 

[wayne]

the waterboard has there own rules seperateto the regs
look up the rules in the osg page 64 (old book new 17th not out yet)
post back if still unsure

 

[wattsup]

Normally, control voltage should be separate. But,... I'm not certain btw, if the interlock lv feeder is used on the same piece of equipment the mains feed is controling. I'm fairly sure it's ok to do so.

 

[Spudmiester]

cheers for the replies fellas !

 

[rumrunner]

hi
Absolute no no ,in my opinion,whatever ythe regs say ,and i would go as far as using screaned cable for the 24v, i have had variovs faults over the years ,mainly with plc controls where voltage has been induced from ac into dc lines,so for that reason alone i would not do it

 

[spark-doctor]

The regs say you can do if you comply with one of the conditions in 528.1 but as Rum says be careful. You could get some strange goings on.

 

[Spudmiester]

hi
Absolute no no ,in my opinion,whatever ythe regs say ,and i would go as far as using screaned cable for the 24v, i have had variovs faults over the years ,mainly with plc controls where voltage has been induced from ac into dc lines,so for that reason alone i would not do it

Cant say I would use screened, but certainly a separate SWA,as it was not driving a PLC input, but a contactor coil.


Rum is back lads !