PVC pipe conduit for 12 volt cables

J

jaj63207

Member
Joined
Dec 2, 2006
RO Number
24411
Messages
122
I am in the process of installing a Xantrex Marine 2000. Using 4/0 Ancor cable. Can I safely use a 2 foot section of Schedule 40 to route the + and - cables for a portion of the trip through the engine compartment. Carver 3607 with Crusader 350's.

Thanks,
Jimmy
 
My only concern would be that eventualy the ends of your Schedule 40 would wear through the protective insulation on your wires over time..
It would take very little vibration to start the wear process..
 
I think if you used a packing nut on each end; or simply gooped it up really well with silicone caulk, you could prevent any chafe.
 
there are specs for the size and type of conduit to be used. Heat buildup in the confined space is a primary consideration. look here
 
Looks like two 4/0 cables in a 2 1/2 pipe will have plenty of tolerance. Bruce, you and some of the other guys on this forum amaze me with the amount of knowledge you have. You just don't know how much I appreciate your sharing that knowledge. This inverter install is major deal for me and ya'll have certainly made me feel better about reducing the oddds of smoking something in the system and passing survey should I ever decide to sell the boat. Many thanks.
Jimmy
 
quote:
Originally posted by pdecat

there are specs for the size and type of conduit to be used. Heat buildup in the confined space is a primary consideration. look here

Click to expand...


THANKS!!!
Just printed that and put it in my boat folder.
 
i would almost think that pvc wouldn't be such a great idea.....in case heat were to build up in your cable for some reason.
i had done some re-wiring on mine and covered everthing with that "split-loom plastic stuff that you see in automotive applications all the time.
then i read somewhere that that was a stupid idea---that plastic crap can turn an overheated wire into a dripping, melting, spreading fire.
i ripped it all out. all of the wires are now visible. after rethinking the whole thing....everything being visible seemed better. easier tracking problems...etc...etc..
just a thought...
 
Wires need to be supported--either with clamps, in races or in conduits. Remember that "Conduit" is gray PVC pipe. Each foot of 4/0 cable weight is about 3/4 lb (the two wires are 1.5 lbs a foot)--so if you are supporting it with either nylon cable clamps or SS Cushion clamps you probably want to support it at least every 6".
 
The gray PVC conduit that Bob speaks of is sunlight resistant, so that is what you should use. It comes in 10' joints. 2" will have plenty of room for two 4/0 cables, even cable with thick insulation. You can get 2" terminal adapters which will glue on and have threads on the end. You can then get 2" plastic bushings which screw on the threads to avoid having a sharp edge which might cut the insulation over time. All these materials are available from any electrical supply house. Plenty of boats have chases built in that serve the same function as the PVC conduit, there is no reason you can't do this.
 
My invereter install manual also suggested that you twist the cables if you have much of a run - I believe it's to reduce the inductive effect of the cables being close together.
 
Never heard of that one. Unless it's close to the compass I can't see why it would matter, either. But if that's what they want, I'd do it.
 
Twisted pairs have self-cancelling inductive fields.

From a NASA document on EMP protection for rockets:

"Shielding guidelines were established after the critical failure of AC-67. In order to reduce magnetic induced voltages in cable wires, it is possible to design cables such that the induced voltages can be self-cancelling. This is completed through twisted-pair wiring enclosed by a copper braid shield. The following shielding list can be applied to all launch vehicles."

So you see; it really is rocket science! ;)

--

Twisting reduces incoming and outgoing high frequency interference. It is generally a good idea in DC/low frequency AC wiring.
 
So, unless you're near the compass, what's the problem with an inductive field?
 
"what's the problem with an inductive field"

Well, first, I think that twisting is a good idea. What this does is reduce in and out RF interference. You get the inductive field regardless (:)), but by shaping it to act as a low pass filter, you "clean up the power supply" as a nice side effect ( and incidentally, to a small degree, reduce the damage from a glancing lightning hit ). Another possible answer to your question is that this field ( which you cannot get rid of ) represents part of the power loss in cables.

Note that with devices such as inverters that demand high current, pulsing DC, you produce Radio Frequency Interference. By twisting the power leads to the ( for example ) inverter, you stop ( greatly reduce ) the power supply leads from radiating rather strong RFI.
 
It ain't rocket science, telephony guys started it over a 100 years ago.
 
You must log in or register to reply here.
Back
Top