electrical query

[glynnffc]

Is it detremental to run both A/C and DC through the same conduit?
I seem to remember something about having to keep them apart, but can't find any specific references in any of my books.

 

[nimbusgb]

50 hz AC may impose noise on DC circuits but I dont think this will be too much of a problem, the biggest concern may be that in a failure situation you could conceivably end up with the mains AC getting shorted to the low voltage DC side of things which could be dangerous.

 

[VicS]

They should be kept apart. Seems sensible to me.

ISO 13297 says:

"11.3 An a.c. circuit shall not be contained in the same wiring system as a d.c. circuit, unless one of the following
methods of separation is used.
a) For a multicore cable or cord, the cores of the a.c. circuit are separated from the cores of the d.c. circuit by an
earthed metal screen of equivalent current-carrying capacity to that of the largest core of the a.c. circuit.
b) The cables are insulated for their system voltage and installed in a separate compartment of a cable ducting or
trunking system.
c) The cables are installed on a tray or ladder where physical separation is provided by a partition.
d) A separate conduit, sheathing or trunking system is used.
e) The a.c and d.c. conductors are fixed directly to a surface and separated by at least 100 mm."

 

[Stemar]

[ QUOTE ]
the biggest concern may be that in a failure situation you could conceivably end up with the mains AC getting shorted to the low voltage DC side of things which could be dangerous.

[/ QUOTE ]This is why I wouldn't do it, though I can't help feeling that if that kind of failure of wires in a conduit occurred, the wrong kind of electrickery would be the least of my worrries. I suspect I'be far too busy trying to keep the sea out /forums/images/graemlins/shocked.gif

I would certainly keep AC as far away as practicable from VHF and transponder cables, though.

 

[Ceirwan]

Keep them seperate, mistakes could easily happen if they are together!

 

[glynnffc]

Thanks for all the replies guys. It seemed sensible to keep them apart and now I'm sure.

 

[William_H]

I reckon this is one of those rules easy to write and be very conservative, but not so easy to comply with in a small boat. Chafing failure of one wire against another seems to be the concern. Unfortunately now the rule is written you would feel obliged to comply. Seperation would give a huge safety margin which might be out of proportion to the danger of the the 240v cable chafing on some other metal part causing a shock hazard.

good luck olewill