# [EVDL] High voltage wiring next to low voltage wiring



## EVDL List (Jul 27, 2007)

Hello Corbin,

When we install industrial wiring with different voltage and phasing range, 
it is best to group the same voltage wires together in a separate conduit or 
duct way. Each wire then can have its own voltage rating. Do not place 600 
voltage rating wire that carries a higher voltage then a lower voltage 
rating wire as for 12 volt.

You can group wires together with different voltages, if all the wires are 
rated at the highest voltage. I use 600 volt double jacket wire that is 
design for chassis work. It has a thicker softer insulation than the wire 
that is design for conduit.

If the lower voltage wires are control voltages and communication systems 
between sensor and instruments, these wires should be shielded or sometimes 
double shield.

I run all my power cables, charging cables, high voltage, low voltage, 
communication systems and the Link-10 cable all in the same duct way that 
goes through the center console in the vehicle.

The comm wires and Link-10 cables are double shield where there is a 
floating ground shield around each wire which is bundle together, inner 
jacket and another ground shield that is only connected to the vehicle 
chassis ground.

I then install each cable and wire circuits in a separate black plastic 
thinwall flexible conduit made by Thomas and Betts or you can use wire loom 
you can get at a auto store. Thomas and Betts make black plastic conduit 
box connectors that will attach to these type of conduit. It makes a 
professional type of installation where you do not have any bare wiring 
showing.

I also run a counterpoise ground system in my EV. Instead of relying on the 
sheet metal of a vehicle to carry the grounding circuits, I run a No. 1 AWG 
39 strand insulated copper wire in a complete circle around the inside of 
the vehicle from the negative of the 12 volt battery or 12 volt DC-DC 
converter and then back again to the negative.

Each panel is ground by using a plated through bolt standoff that attaches 
the wire connector and take off to other equipment. Then I may have 
separate ground wires going to the negative too. I also ground all 
electrical enclosures and chassis plates at two points each.

In my comm system, I do not have any noise at all on my AM, even though the 
speaker wires which are also double shield run though the same duct way.

Roland







----- Original Message ----- 
From: "corbin dunn" <[email protected]>
To: "EVDL Discussion List" <[email protected]>
Sent: Friday, December 31, 2010 6:12 PM
Subject: [EVDL] High voltage wiring next to low voltage wiring


> Hi All,
> This might be a silly question, but I'm new to building my own EV. Is it 
> bad to have a single high voltage 2/0 wire right next low voltage wiring 
> for the car? Or, will there be some sort of back EMF noise that will 
> affect things? Or, is it okay to do this?
>
> thanks!
> corbin
>
>
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## EVDL List (Jul 27, 2007)

Hi Roland,
Thank you very much for the detailed explanation! I'll look into running my HV cables separate from the other ones.

--corbin



> Roland Wiench wrote:
> 
> > Hello Corbin,
> >
> ...


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## EVDL List (Jul 27, 2007)

Corbin,

I can't add more to the excellent technical explanation by Roland. I can add my experience with HV/LV wiring. 

I have a single 2" PVC conduit running from the engine compartment to the battery pack in the rear. The conduit contains the 144V traction pack wiring as well as several 12V wires. I have not had any problems with this set up (almost 2 years and 8000+ miles). 

The only EMF problem I have had is the static produced on the radio. To get around this I just use bluetooth streaming of internet radio or Pandora from my Blackberry to the radio. 

Barry Oppenheim
www.justanotherevconversion.blogspot.com
-----Original Message-----
From: corbin dunn <[email protected]>
Sender: [email protected]
Date: Sat, 01 Jan 2011 08:51:36 
To: Electric Vehicle Discussion List<[email protected]>
Reply-To: Electric Vehicle Discussion List <[email protected]>
Subject: Re: [EVDL] High voltage wiring next to low voltage wiring

Hi Roland,
Thank you very much for the detailed explanation! I'll look into running my HV cables separate from the other ones.

--corbin



> Roland Wiench wrote:
> 
> > Hello Corbin,
> >
> ...


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## EVDL List (Jul 27, 2007)

Corbin, you've had some good advice on this topic. I can try to add a 
few things, too.

It's generally good practice to separate high-power and low-power 
wiring. There are engineering reasons to do this (noise coupling, 
leakage currents etc.), but the main reasons are more a matter of 
safety, serviceability, and practicality.

Noise coupling
--------------
When two conductors are placed side by side, you have inductive and 
capacitive coupling between them. AC signals on one wire can cross over 
to the other wire. The closer the wires, and the longer they run 
together, the worse this coupling gets. The coupling causes radio 
interference, false readings on instruments, makes computers produce bad 
results, etc. So it's best to keep them apart.

If you're forced to run wires together, you can put a grounded metal 
shield between them to eliminate most of the capacitive coupling. This 
is the purpose of adding a foil or braided copper shield around wires.

You can arrange the wires in pairs, with identical and equal currents 
flowing in opposite directions, which cancels out most of the inductive 
coupling. For example, a +power wire goes out, and its -return wire 
comes back, tightly bonded or twisted together.

If the coupling problem is severe, do both. Pair all the wires, and 
twist the pairs together. Put grounded shields over them, and ground the 
shields at only one point (so there is no current in it, which would 
upset the balanced currents in the wires).

Leakage currents
----------------
No insulator is perfect; they all let a little bit of current flow. 
Normally, this current is too low to matter. But it can become 
significant if:

-the voltage between the wires is high
-the insulation is thin
-the wires are close
-the wires run together for a long distance
-the quality of the insulation is poor
-the insulation is wet, dirty, or damaged

Leakage currents don't usually affect high power circuits, but they can 
cause noise or false readings in low-power circuits. Leakage currents 
can also create a shock hazard, since even small currents can kill, or 
at least give you a nasty surprise when you least expect it.

Serviceability
--------------
Mixing high and low voltages can create servicing nightmares. A loose 
screw, errant solder blob, a bit of stranded wire, or carelessly placed 
tool or finger can short things that should *never* be shorted.

Safety
------
Finally, you want high and low voltages well apart in case of an 
accident. Things obviously get seriously mangled in a major crash. But 
you don't want a little fender-bender or big pothole to cause some cable 
to get pinched that shorts wires together.
-- 
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377	| There is a crack in everything
leeahart earthlink.net	| That's how the light gets in -- Leonard Cohen

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