I would say yes. Treat the whole car as an appliance - it has a metal case and can't be certified as double insulated, so the case must be earthed.
Things get more complex for a boat, where galvanic corrosion in salt water needs to be considered, but for a car I'd certainly connect the body to the earth in the connector.
Pete
How about a nice hefty battery cable to a proper Anderson connector? You can keep only the low voltage on the car then and there'd be next to no voltage drop on the extra length of cable with the low current of a charger and the large CSA. You'd also have the added bonus that you could use the connector for a plug in set of jump leads. I keep meaning to get around to doing this on my kit-car.
SteveW
Or milk-float style?
In message , "Dave Plowman (News)" writes
I can go for several months without driving my car, but I do have a good battery in it (and a solar plug in the cigarette lighter charger). I just don't have problems
I've got a fairly high quiescent draw on it - lots of extra junk fitted. ;-)
No one has suggested an earth rod :o)
That is a seriously inefficient charger.. 40x240 >> 70x72
Adam
Pete Verdon wibbled on Wednesday 16 December 2009 20:05
I would agree with that. Earthing the car will be a better bet IMHO than trying to insure that there is no way that a mains cable entering the car cannot become damaged on a sharp with of metal and become live.
Another way would be to take the double insulated approach, but to use SY flex to take the mains in and earth the braid.
That flex doesn't meet the mechanical protection criteria of the IEE regs in way that armoured does, but looking at it objectively, if the outer sheath does become cut, it will provide some mechanical and electrical protection.
But the obvious belt and braces approach, as others have mentioned is to talk SELV into car.
Might be worth having a look at some engine preheaters - those are mains - see what they do regarding earthing.
Tim W wrote: Earthing the car will be a better bet IMHO than
As long as you're not planning to take the SY flex into the battery charger, which would defeat the double-insulated properties of the charger and be more dangerous!
It's worth pointing out that the reason Caravans and motor homes are required to be earthed is because human beings occupy them naked and wet when the mains electricity is connected.
In Dave's case, he's going to be fully dressed and he's going to disconnect the mains before he gets into the car, so the risk of electric shock is minimal.
However, there's no obvious downside to fitting a 3-pin inlet to the car and earthing to the chassis/body. He should not under any circumstances, however, consider modifying the charger from Class II to Class I (i.e double insulated to earthed).
Cheers, DaveyOz
Dave Osborne wibbled on Thursday 17 December 2009 17:43
No, I was thinking of the SY flex being the flying lead used to plug the charger into the house supply - that being the bit that is vulnerable to chafing. The charger and its immediate wiring can be secured and protected.
I'm not sure I entirely agree that feeding an earth shielded flex into a Class II appliance makes it dangerous though. What failure scenarios could that cause that would result in a dangerous condition?
Class II appliances are designed such that if a live wire goes astray inside the unit, there is no external metalwork which can become live. (this is not, I stress, saying that there would be no external metalwork at all).
In the event of a fault the unit will simply stop working or pop a fuse (thermal or over-current), rather than become hazardous to touch. This allows the manufacturer of the product to make the internal chassis live, to have various different bits of internal metalwork at different potentials, etc.
This, in turn, facilitates value engineering the design for minimal production costs. It also allows the product designer to create a product with mixed metal and plastic components (e.g. a hand-held electric drill) without needing to ensure that there is contiguous earth bonding within the unit.
By introducing an earth wire (or indeed armour/screening) into the interior of the unit, you would then effectively make it a Class I appliance. You would then have to make an electrical safety reassessment of the product design. Depending on the nature of the product this could be straightforward or it could be virtually impossible to achieve without extensive design reworking.
Dave Osborne wibbled on Thursday 17 December 2009 19:37
Yes - I agree with all of that in spirit. But I don't make formal electrical assessments when I build mains devices from scratch, other than common sense, sensible design and good workmanship. I've applied more consideration in my devices to making sure that a SELV part cannot reasonably contact a mains part (due to wire falling off) than I've observed in at least one appliance I took to bits once which had all the relevant markings on it.
I've built Class I and Class II appliances and applied the relevant engineering considerations to both.
My argument is that in this scenario, we have introduced an extraneous metallic part - yes. But that part is earthed by design. I see very little that can go wrong.
OK - if we were selling this to the general public, one would expect to make a formalised assessment. However, as always, this is a one off for personal use. It is of course down to whether the OP feels happy with doing such stuff (this is a DIY group), but being aware of the cautions given I think he's got reasonable grounds to make a judgement.
I'm merely presenting the engineering argument "what could go wrong"?
(As I said, I intended the SY flex to connect between the mains supply and a recepticle in the car - but as we're starting to discuss the case of modifying a Class II device, then why not - it's interesting.)
If we reduce the argument further, noone should put a plug on a class I device because they might wire it incorrectly?
I'll just add, this is a "friendly argument" AFAIC as there's no way for you to deduce that from the tone of my tapping ;->
Cheers
Tim
The mains lead twixt 13 amp socket and Buccaneer inlet will be 1mm TRS. The back of the chassis plug covered by a strong plastic box with a side exit stuffing gland which the supplied mains lead on the charger will come out of - a distance of only a few inches. Likely behind the boot carpet - although that's not yet decided.
No real problem with anything you've said, Tim.
Unfortunately I can't take the discussion much further as I've never worked for a company which mass-produces stuff to Class II, so it's all personal opinion and speculation from here-on-in ;-)
I do suspect that when you say you've "scratch built to Class II" (to paraphrase), you should probably say you've "scratch built without earth". I think that you couldn't reasonably argue that you've scratch-built a Class II appliance because the standard will likely have all kinds of subtleties like creepage, clearance, dielectric strength of plastics, flame-retardance, etc, etc. which you will not have been in a position to consider (you don't have full specs for the materials used) or test for (you likely don't have access to a proving laboratory with all the required equipment). Also, I suspect that some of the tests are destructive, so essentially Class II is a type approval.
I agree that if you're "scratch-building without earth" then it is reasonable to apply good engineering practice and common sense. Very often you're not reinventing the wheel, so you can confidently follow standard practice. I would, however be very cautious about dismantling an existing Class II appliance and re-engineering it because it may not be obvious what abominations have been made to the design as part of a value-engineering exercise which would not have been considered had the item been an un-enclosed or Class I product.
For example, if I were building a piece of equipment into a 19" rack enclosure and I had an SMPS which happened to be Class II, I would be inclined to leave it in its own plastic case and install it in the rack enclosure as a "black box" taking care to interface to the existing inlet and outlet connections and fixing it down with (say) a cable tie rather than screwing into the case.
If OTOH the SMPS was Class I, I would consider dismantling it and discarding the case (particularly if I needed the physical headroom). In this case I might well discard the inlet connector and the outlet cable and wire to it as if I bought it as an unenclosed product.
Either way, the "whole thing" would be a Class I appliance.
Cheers, DaveyOz
While wandering up the highstreet in Canterbury yesterday, I noticed a mobile police station that had a 240v inlet. Above it was a large sticker describing all the earthing setup that was required before use.
Would have taken a photo but it was snowing and they appeared busy with a rather "happy" guy from the pub so I passed them by...
Might be worth a look should you come across something similar :)
Darren
That sort of thing is likely to have 13 amp etc sockets within it. So 'caravan' type regs would apply. Working in TV, I've seen plenty of trucks that have 240 volt circuits within them - and it's usual to fit a CU with full RCD protection. But a bit overkill for what I'm doing.
I dunno, you could have it between the front seats in place of the flux capacitor :-)
Many many years ago when I had a vehicle with an unreliable battery I did something like that. Two radio aerials on the car roof one connected to + other to the body work. Hanging in the garage a couple of wire coat hangers stuck in a wooden beam and connected to the charger. aerials touched hangers and connection made without faffing around with plugs.
G.harman
In message , " snipped-for-privacy@gglz.com" writes
Worse than that, it varies between models from the same manufacturer. Bloody stupid idea.
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