HV in conduit or not? or what?

Technical discussion on converting internal combustion to electric
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Peter C in Canberra
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HV in conduit or not? or what?

Post by Peter C in Canberra »

Hello All,
I've bought all the big ticket items, go the motor in and now I'm getting down to the finer detail planning of layout etc. However, in Canberra there is only one completed EV to look at. So I come to a question....

I have several meters of the 50mm2 cable from ZEVA, black and orange. The cells will be behind the back seat in the spare wheel well and hatch area, just about everything else in the front. I will get proper cable glands for where the cable passes to the underside of the car and roughly follows the path vacated by the exhaust pipe. So, do people just use the double insulated cable directly clipped to the metal under the car or does it get further protection in a conduit? If it is passed through conduit doesn't this give it more scope to move and abrade or fatigue than if it were pinned at frequent intervals against the underside of the car tucked up in the tunnel? If it is tucked up without conduit is there a good source of clips of the right size to match the cable diameter? Are the clips (with or without conduit) just attached with self tapping screws?

I have the red emergency disconnect button and will have this on the driver's side of the tunnel next to the gear lever. That would be an exposed live connection under the car. Do people put a cover of some sort over that? If so, is there a neat way to do it that I could copy?

I will have the mains connection under the fuel filler lid but the charger will be in the engine bay. Consequently I need to also run mains cable to the front following the same path as the high voltage DC. Are there particular rules to do with mains? Do I use 15 amp house wiring cable? That has solid cores so it might be less tolerant of vibration than 15 amp flex. Should I prefer that? Would either be required to go in conduit with the same concerns about this allowing more vibration and less ability to inspect?

Thanks for tips and comments!
Peter.
Daihatsu charade conversion 2009-18, Mitsubishi iMiEV 2013-2019, Holden Volt 2018-2019, Hyundai Kona 2019-present on the ACT's 100% renewable electricity.

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Johny
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HV in conduit or not? or what?

Post by Johny »

Hi Peter.
I think the conduits are necessary. I'll be interested to see others comment on this as well.
If you use PVC and size it correctly then the wires will be pretty tight and have very little tendency to move. Most electrical suppliers (Middys) sell a slippery goo that you can coat the cables in to pull them through if it's very tight. Conduit clamps and self tappers should be fine except, of course, where you are maybe going into the floor. Bolts and nuts with shake-proof washers are the go there (bolt on inside of car). Where you can, you could use large cable ties with common sense telling you if the metalwork is too sharp to safely use them.

Since the car is a plug-in appliance you can use standard 3 wire flex for the mains. I would put it in a conduit as well. It must run in it's own individual conduit though. Since it will be enclosed, go up a size - use a 15 Amp flexible cable.

The disconnect button. You should be able to find a small plastic case to mount it in, then use the same mountings to secure it to the car. The case I have in mind is the same size that industrial emergency stop buttons come in.
This ones on the dear side ($26):
http://au.farnell.com/imo/bg1/enclosure ... dp/9940073

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HV in conduit or not? or what?

Post by drowe67 »

Hi Peter,

I routed my cables out of the driver side panel of the boot towards the rear wheel (I didn't want the gland facing forward) then did a left turn and up through the exhaust tunnel.

I used an extra layer of flexible conduit where the cables would rub against the car, and that was just some plastic grey water pipe as I got sick of spending big $ at the the electrical shop!

I used these cable clamps to secure the cable under the car:

Image

My mechanic gave them to me (he used them for securing brake lines on a hot rod), so I assume they are available from auto parts stores.

I used the existing mounting points and bolts from the exhaust system where available and a bolt drilled through from inside where there was no convenient hole. A self tapper doesn't sound strong enough to me, the cables are quite heavy, and thr ends would poke through into the cabin.

Make sure the cables don't touch any brake lines - I got pinged for that on my inspection.

I would route the AC charger cable inside the car under the carpet, say along the passenger side. It helps if you pull the seats out to route cables internally.

I too located my circuit breaker/emergency disconnect in the trans tunnel. I was slightly uncomfortable with this location. I insulated the terminals with some (i) a layer of flexible conduit (grey water pipe fitted nicely) then (ii) large heat shrink (electrical wholesaler) on top. I then bolted a metal plate (from the exhaust system) underneath for mechanical and water protection.

But I like the idea of enclosing it in a box better.

- David
Driving an EV every day
http://www.rowetel.com/ev.html

Peter C in Canberra
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HV in conduit or not? or what?

Post by Peter C in Canberra »

Thanks Dave,
I'll be careful to avoid the brake lines-good tip. Ditto about the self tappers-that was just lazy thinking-i'll use a proper bolt. I'm now thinking to use some of the flexible plastic stuff with a split up the side that was used originally in the car for bundles of wires, the thinner size is a snug fit over the cables. It has not become brittle in the last 20 years so it will probably last OK and there was more of it at the autoshop. I think I really only need an extra layer of protection against chafing since the cable will be well protected up in the tunnel.
thanks,
Peter.
Daihatsu charade conversion 2009-18, Mitsubishi iMiEV 2013-2019, Holden Volt 2018-2019, Hyundai Kona 2019-present on the ACT's 100% renewable electricity.

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acmotor
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HV in conduit or not? or what?

Post by acmotor »

Reading some of the emergency response services policy on EVs and hybrids reminds us why orange is the colour for conduits (not necessarily wires). Simply, these are potentially dangerous and should not be cut or handled if damaged.
To me, this 'orange' could well be 'painted' on to a grey or black conduit or the conduit wrapped in orange PVC tape (if you can find any).
This is all an essential message to the public and emergency services.

Any EV that is inspected and passed without 'orange' is a bad promotion for EV safety. I would like to speak personally to any 'electrical' inspector who has signed off on non orange.

I would always 'conduit' cables from a mechanical point of view as well as the second layer of electrical insulation.

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Post by acmotor »

I recall working on a motor control installation in Chiba, outside Tokyo a few years ago. It was a new installation in a new factory.

Japan has 200V 3 phase power in most areas.

I was to set up a 15kW VFD running a induction motor under computer control on a centrifuge as part of a package I was commissioning.

The local sparky had provided a 3 phase connection to near the controller location before I arrived and I needed to shut the power off to make the final connections.

I followed the wires along after finding their ends live but at least pvc taped. They were 50mm sq x 3 roughly twisted together individual wires with no overall jacket or conduit. They were tied (quite neatly) with fencing wire to the steel frame of the factory shed and went out to a juntion box at the corner of the building 50 metres away.
Great, open the box - no switch ? just a bundle of twisted and taped cables from around the building. Some went off via circuit breakers to various circuits however the ones of interest to me went straight off to the street via a shallow duct. I followed this and found it went to a power pole, up the side (still no conduit) and wrapped around the street wires !

I quizzed the sparky about this and the translation was "it's fine, that's normal, But I couldn't have the power turned off as that would require shutting down several street blocks." I guess that meant it was live installed as well.

Needless to say, I fitted some HRC fuses and a switch at the VFD end. All done live for a little excitement.

The point of this story ?

When the voltage is lower, so are the standards. Oz people would have had kittens to see the lax installations in Japan.
Mind you, their single phase is often down to 90V, even less on the end of an extention cord. But the currents !!! Extension cords were more like welding cables !


I feel that many EVs are wired to 12V wiring standards, not 72, 144 or more. Yet system voltages are for ever climbing.

If you use respect for pack voltage and correct practice with your wiring. e.g. with conduits and waterproofing and human contact exclusion, then the higher voltages are not an issue.
Also, as I have said before, don't assume that electrically isolating the battery pack from chassis will cover up other bad electrical practice !

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Post by Electrocycle »

yeah I saw some pretty crazy electrical stuff in Japan.
There was a nice outdoor washing machine and drier setup at a Ryokan (Japanese Inn) we stayed at, where they were powered by an extension lead / power board that sat out in the rain with plants growing through it!
Most of the cable was still coiled around a drum and the whole lot ran really hot!
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HV in conduit or not? or what?

Post by Thalass »

Tuarn: Perhaps AEVA could produce a Standard Wiring Practices Manual for convertors? Each aircraft manufacturer has a series of "chapter 20" standard practices manuals, one of which is wiring (along with structures, engines, etc), so something similar for EVs would be a great step in proving both that the AEVA are serious about safety, and provide a solid guide for both converters and inspectors.

Things like conduit colour, minimum distance between tie points. Separation of power and data lines (though that's not a concern for most conversions). Whatever the safety team can come up with, I guess.

I'll drive an electric vehicle one day.

Peter C in Canberra
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HV in conduit or not? or what?

Post by Peter C in Canberra »

For what it's worth, I started this thread and can now report that I have started wiring up with some 70mm2 fine stranded, double insulated cable I found at a local metal recycler. It has a blue covering so I have put it into some 25mm, flexible, orange, UV-stablised, corrugated conduit ($10+$7postage on Ebay). For some reason orange flex was much more expensive than grey at the local lighting shop. I'm using orange for both + and - runs, IE the entire high voltage DC circuit and will mark the polarity some other way. With the traction battery system floating independent of the chassis I can't see any reason why the + is any more or less dangerous than the -ve.
Peter.
Daihatsu charade conversion 2009-18, Mitsubishi iMiEV 2013-2019, Holden Volt 2018-2019, Hyundai Kona 2019-present on the ACT's 100% renewable electricity.

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Post by Rob M »

Hi Peter C,
True, positive and negative can be equally as dangerous from an electrocution point of view.
There is a need to mark positive and negative so a wrong connection is avoided. A serious spark would occur if two banks of batteries were connected together in series instead of parallel, especially if the fuse was inline somewhere else.
Cheers
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Post by HeadsUp »


i am all for using orange conduit , but PVC conduit will melt and burn if the cable overheats , that shouldnt ever happen if we have short sensing contactors. but........

i want to find orange heatproof non conductive conduit if possible

anybody seen such a thing ?

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Post by acmotor »

In a way, it is why wiring is done to acceptable standards e.g. AS3000 or similar.
A wire should be selected never to overheat under working conditions and should be fused or current limited so that it will never suffer a fault condition that will melt its insulation let alone its conduit.

Conductive conduits (for most applications) were ruled out a long time ago as the insulation properties of (e.g. PVC) are very desirable for electrical safety. 105°C seems to be an acceptable short term max temperature for PVC conduit. Some fibreglass, silicon rubber and epoxy based conduits go over that.

HeadsUp, I understand your heat point but design for working and fault conditions should mean that you never get to that 'hot' condition.
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Post by fuzzy-hair-man »

Am I correct in assuming that most of the PVC conduit and pack to controller or controller to motor wiring is going outside of the vehicle? If so I'd be a little concerned about how well the conduit will stand up to being hit by stones, my experience is that PVC doesn't stand many stone hits before it breaks.

There seems to be a reluctance to put this wiring inside the car, is there a particular reason for this? given that it is well insulated, is it unsafe to have this in where the people are? or is it just following the convention set by fuel lines, brake lines, and exhaust all being outside the car?

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Post by HeadsUp »

fuel lines running through the interior of the vehicle means unvented fuel / gas can accumulate , open a car door , interior light turns on - kaboom

at least fuel lines under a car are vented.

brake lines are run inside chassis rails wherever possible.

electrical is a different catagory . but personally i would still like double insulation of HV and protected cabling under the car for LV

LV cables are too thick to run under the carpet are they not ?
LV run under the car will probably have an almost straight line run whereas through a car interior there is more lumps bumps twists and turns resulting in longer cable and more voltage drop.
cable run under the car is more easily inspected for damage than if it was run under the ( flammable ) carpet

personally i am hoping to have a thin walled steel conduit with cable run inside for LV DC running under the car

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Post by Johny »

Personally I think it's a matter of practicality. Trying to run a 18-25mm conduit inside the car is difficult. As HeadsUp says, under the car is a reasonably straight line and is easily inspected.

Peter C in Canberra
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Post by Peter C in Canberra »

...and the route previously followed by the exhaust pipe is available, reasonably direct and generally fairly well protected.
Peter.
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Post by weber »

Go to Bunnings (etc) and ask in the building supplies section, for a steel top-hat ceiling batten. This is about 40 mm wide and about 25 mm high and comes in a 6.1 metre length. It's coated in zinc-alume and then blue anti-glare. I get the staff to cut it in half with their aviation-snips so I can fit it in the van. Very cheap.

The thing is, it fits beautifully over the top of 20 mm PVC conduit, rigid or corrugated, to give it added mechanical protection while still giving you the double insulation properties of the conduit. It has flanges that let you easily tek screw or pop rivet it to whatever surface you're running it on, and you don't need saddles for the conduit. It is easily cut with aviation(tin)-snips to go round corners piece-wise if necessary.

I assume that where folks are writing "HV" they really mean what is called "LV" in the electrical industry and in all relevant Australian Standards, namely DC between 120 and 1500 V or AC between 50 and 1000 V. And what you are calling LV is really ELV (extra low voltage).

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