Get your charge cables regularly inspected and tested!

[Glan gluaisne]

Every year I do a periodic inspection of all portable electrical stuff in the house, pretty much a PAT test, with a few extra checks. Had a near-failure this year, on an infrequently used 10m long Type 2 charge cable. In theory, anything over 1MΩ on an insulation test is a pass, but the majority of things I test tend to give a full scale reading for insulation resistance (199.9MΩ for my MFT). when I tested this 10m cable this year, I initially got an insulation resistance reading of just over 1MΩ, in theory a pass, but so far different from its usual reading of 199.9MΩ as to make me very suspicious that something was awry.

This cable was last used just before I sold my i3, so perhaps 6 weeks ago, and it may well have been raining at the time. I decided that water in the connector was possibly the most likely culprit, so took the connector apart, and sure enough it was very wet inside:

I'll leave this to dry for a few days and test it again. Judging by the light corrosion on some internal screws I'd say that it's been wet for some considerable time. Unlike the Dostar and Rolec connectors, that have a drain hole at the bottom, this connector does not, so any water that gets in cannot get out. I shall drill a small drain hole in the bottom before I reassemble it!

The moral of this story is to get your cables periodically inspected and tested. It only takes a few minutes to do, and is well worth it for peace of mind. I doubt there's a risk from having a degraded cable like this, but there is a possibility that it would just trip the RCB/RCBO, and so stop you being able to charge. Could be a nuisance if away somewhere and reliant on getting a charge from a destination charge point.

Finally, if anyone wants their cables checked (not ones tethered to equipment) and they are within reasonable travelling distance from me (roughly half way between Salisbury and Shaftesbury, just off the A30) I will happily test them for free.

 

[Glan gluaisne]

Just had a deeper look inside:

This cable has been coiled up in a cupboard inside the house since I sold the i3 earlier in November, yet it still has all this water around the contact pins. Clearly the O seals around the contracts don't seem to be doing much! I'll smear some silicone grease around the outside of these when I put it back together again, once it's dried out.

 

[Oil4AsphaultOnly]

Wouldn't storing them indoors be better advice (like storage shed, or just a weatherproof plastic bin? I never keep any portable cables stored outdoors.

Besides, however the moisture got in, that should be where it goes out.

 

[Glan gluaisne]

Wouldn't storing them indoors be better advice (like storage shed, or just a weatherproof plastic bin? I never keep any portable cables stored outdoors.

Besides, however the moisture got in, that should be where it goes out.

It's always been stored in the frunk of the car, in the dry (except for the past few weeks when it's been indoors in a cupboard), so the only time water can have got in was when it was being used. I left the i3 on charge on my spare charge point (other end of the drive, with a fixed plug) not long before I sold it, in order to ensure it was fully charged. My guess is that water got in then, as this isn't a cable that I've used a lot, it's really just a useful thing to carry, as being 10m long it often enables a charge from a charge point that's blocked by an ICE.

Not a clever design of connector, as the joint runs horizontally (as seen when plugged in) rather than vertically as many have the joint arranged. With no drain hole it's inevitable that water is going to remain trapped in there. I'm surprised by the amount of water around the contacts, though. That area is pretty well sealed up, with O seals around every pin, plus no obvious route for water to have got in that way.

 

[TSLA Pilot]

While meant as a public service, I presume none of this is a factor with Tesla's equipment?

This is the first I've ever heard of this issue so am curious.

Thx.

 

[Fredneck]

Wouldn't storing them indoors be better advice (like storage shed, or just a weatherproof plastic bin? I never keep any portable cables stored outdoors.

Besides, however the moisture got in, that should be where it goes out.

Unfortunately it is hard to make a waterproof enclosure. Water can get in if there is any slight compromise. That doesn't mean water will get back out.

I would not drill a hole in the housing if I would going to use it in any wet environment... such as outdoors. Even if there is no rain, dew can cause moisture to enter through a momentary gap such as pressure being placed on the pins while inserting or withdrawing the connector.

 

[Glan gluaisne]

While meant as a public service, I presume none of this is a factor with Tesla's equipment?

This is the first I've ever heard of this issue so am curious.

Thx.

I've no idea. The cable that came with my M3 isn't a Tesla product, it's a standard Mennekes one. At collection we were told there were two different makes of cable, a blue one (the Mennekes one) and a black one, and that if we had a colour preference we should barter with each other to swap them around (this was at West Drayton). My Tesla (Mennekes) cable has never been used, but tested out perfectly (as I'd expect for something fresh out of the bag).

I have absolutely no idea if any of the other brands of charge cable that have been supplied are as bad as the 10m one I've just tested, or not. The failing I found would not be apparent in use, as it was still technically a pass, as the minimum allowable insulation resistance is 1MΩ, but in my view, a connector with that much water in it is unacceptable, especially as it has been stored indoors, in the dry, for several weeks now.

There is no requirement for people to have any portable appliance inspected and tested, although there is a very strong recommendation that all domestic electrical installations should be given a periodic inspection at least every ten years, and my own very strong recommendation is that this needs to be done every five years, now we have RCD protected installations (that's based on personal experience of having seen a fair number of failed RCDs/RCBOs, that outwardly seem OK).

If what I found this afternoon saves someone having a failure to charge, or an RCD/RCBO trip, then it will have been worthwhile. If it results in people looking more closely at their cables, and perhaps opting to get them inspected and tested that's great. I should stress that I'm in no way trying to line the pockets of those that wish to make a profit from this sort of testing - anyone with suitable test gear can do this testing very quickly and easily.

 

[Glan gluaisne]

Unfortunately it is hard to make a waterproof enclosure. Water can get in if there is any slight compromise. That doesn't mean water will get back out.

I would not drill a hole in the housing if I would going to use it in any wet environment... such as outdoors. Even if there is no rain, dew can cause moisture to enter through a momentary gap such as pressure being placed on the pins while inserting or withdrawing the connector.

Many Type 2 connectors have a drain hole in the underside, specifically to let water out that gets in. This is the first Type 2 that I've seen in the past 6 years or so, that has no drain hole. Even our standard outdoor electrical outlets have a drain hole drilled at the lowest point, both to allow any moisture to get out, and allow the inside of the enclosure to breathe, with changes in atmospheric pressure. Often the positions for these holes are just marked, and it's up to the installer to drill a hole of around 2mm to 2.5mm at the lowest location.

In the case of this connector, there were literally puddles of water inside it, despite it having been indoors for around a month or more. That tells me that the design is flawed, and as this was a purchased, pre-made, Type 2 cable, there seems a fair chance that others will have the same problem.

 

[Oil4AsphaultOnly]

Unfortunately it is hard to make a waterproof enclosure. Water can get in if there is any slight compromise. That doesn't mean water will get back out.

I would not drill a hole in the housing if I would going to use it in any wet environment... such as outdoors. Even if there is no rain, dew can cause moisture to enter through a momentary gap such as pressure being placed on the pins while inserting or withdrawing the connector.

No, not waterproof, weatherproof: resistant to UV, rainfall, snowfall, and road salt. Those dark colored storage bins that keep the weather out, float in a flood, but aren't airtight.

 

[Glan gluaisne]

Just to close this off, I left the connector apart overnight, having washed all the wet areas off with IPA, to encourage them to dry out. Reassembled, with silicone grease around the O rings and all seems fine, the insulation resistance is back to being off the scale (as it used to be).

I did find two small partial holes on the underside of the connector, both at the lowest part of dips in the moulding. These were too small and deep (I think) to be mould ejection pin marks, and I suspect they may have been intended to go right through to the inside of the plug. This would make a lot of sense, as other Type 2 plugs I've seen (other than the fully potted Tesla ones) have similar sized drain holes. Both holes have been drilled out to 2.5mm, so with luck the problem shouldn't happen again.

I'd still suggest that it is a very good idea to regularly test cables like this, along with any other portable appliance. It doesn't take more than a few minutes, but does need some basic test gear.

As I wrote initially, if anyone wants to test their cables, or anything else, and they live near enough to me, then just contact me and I'd do the inspection and testing for free - no strings attached. Alternatively, you might consider asking a favour of who ever does workplace PAT testing, as the testing needed is pretty much the same (as long as they understand how the two pilot pins/sockets are connected).

 

[kuruma]

rather than fishing for those of us nowhere near where you live, could you teach us how to fish?

A link to a good recommended vid on how to do this yourself would be appreciated.

Thanks very much for posting the warning though.

 

[Glan gluaisne]

rather than fishing for those of us nowhere near where you live, could you teach us how to fish?

A link to a good recommended vid on how to do this yourself would be appreciated.

Thanks very much for posting the warning though.

Not fishing for anything, I'm retired, happen to have some test gear (and the knowledge to use it) and was just offering a free safety inspection/test for anyone nearby - no strings attached, I've never charged for doing electrical work for anyone in my life.

The procedure for inspecting and testing cables is to first clean the outside of the cable and have a good look at it, all over, to check for damage, internally twisted cores, any indication that the outer sheath of the cable has pulled free from the strain relief inside the connectors and damage to the connectors themselves.

If all looks OK, the you need some test gear that's capable of checking both continuity, low values of resistance and an insulation test to at least 500 V. Check each core of the cable end to end for continuity and check the end to end resistance of the power cores. The resistance measured is low (it should be around 0.0034Ω per metre of cable length for 6mm² cores used in the majority of charge cables, plus a bit for contact resistance). An ordinary multimeter is unlikely to be able to measure this.

Next, check the insulation resistance at 500 V, between each of the live conductors (L1, L2, L3, N) and PE, plus between each of the live conductors themselves. A single phase cable will only have two live conductors, L1 and N. The minimum acceptable insulation resistance is 1 MΩ, but the reading should be a great deal higher than that. Anything less than a few tens of MΩ would make me suspicious that there was either the start of some sort of insulation breakdown or that water had got in some how.

The main problem for those wanting to DIY test cables will probably be the lack of suitable test gear. The actual testing only takes a few minutes for anyone with the kit. The description of PAT testing in Wikipedia is reasonably useful and much of it applies to charge cables: Portable appliance testing - Wikipedia

 

[NorfolkMustard]

I don't think Kuruma was suggesting you were fishing for business/kudos Jeremy rather it was a reference to the "give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime" saying

 

[Adopado]

rather than fishing for those of us nowhere near where you live, could you teach us how to fish?

... rather than fishing on behalf of those of us ... (Think this was the meaning.)

Actually Jeremy does feed us some great fish ... but he does teach us to fish too from time to time!

 

[Chronic]

Every year I do a periodic inspection of all portable electrical stuff in the house, pretty much a PAT test, with a few extra checks. Had a near-failure this year, on an infrequently used 10m long Type 2 charge cable. In theory, anything over 1MΩ on an insulation test is a pass, but the majority of things I test tend to give a full scale reading for insulation resistance (199.9MΩ for my MFT). when I tested this 10m cable this year, I initially got an insulation resistance reading of just over 1MΩ, in theory a pass, but so far different from its usual reading of 199.9MΩ as to make me very suspicious that something was awry.

This cable was last used just before I sold my i3, so perhaps 6 weeks ago, and it may well have been raining at the time. I decided that water in the connector was possibly the most likely culprit, so took the connector apart, and sure enough it was very wet inside:

View attachment 488176

View attachment 488177

I'll leave this to dry for a few days and test it again. Judging by the light corrosion on some internal screws I'd say that it's been wet for some considerable time. Unlike the Dostar and Rolec connectors, that have a drain hole at the bottom, this connector does not, so any water that gets in cannot get out. I shall drill a small drain hole in the bottom before I reassemble it!

The moral of this story is to get your cables periodically inspected and tested. It only takes a few minutes to do, and is well worth it for peace of mind. I doubt there's a risk from having a degraded cable like this, but there is a possibility that it would just trip the RCB/RCBO, and so stop you being able to charge. Could be a nuisance if away somewhere and reliant on getting a charge from a destination charge point.

Finally, if anyone wants their cables checked (not ones tethered to equipment) and they are within reasonable travelling distance from me (roughly half way between Salisbury and Shaftesbury, just off the A30) I will happily test them for free.

Very interesting, could you make a YouTube video explaining how we can do this ourselves?

 

[Oil4AsphaultOnly]

Very interesting, could you make a YouTube video explaining how we can do this ourselves?

Jeremy's post seemed pretty thorough, and he was also very clear that the issue isn't the procedure, but the required test equipment to carry it out. I own a few multimeters, and none of them are capable of carrying out the [500v insulation] tests that he suggested.

 

[Glan gluaisne]

Yes, sadly a multimeter isn't really much use except for continuity testing in this context. It also probably won't be able to detect a high resistance in any of the power conductors, as even my 10m lead only has a conductor resistance of ~0.034Ω, and few multimeters are accurate below about 1Ω or so. A small increase in the end to end resistance is often indicative of a bad connection or internal damage in the cable, than may create a hot spot and lead to further damage (the classic case are all the many Rolec RCBO N failures, caused by internal overheating).

It used to be that electricians carried around a van load of test gear, with a bit of kit for each job, so typically an Avo (used for voltage and resistance measurements) a Megger (used for insulation resistance testing, a four terminal earth electrode test box (used to test TT earthing installations), plus a collection of various cable adapters, indicator light boxes, earth leakage simulator boxes, etc . Nowadays everyone uses a multifunctional tester (MFT) which pretty much does everything needed. Mine is old, but still in calibration, and is fairly typical. It will measure very low resistance, insulation resistance at 500 V, continuity, as well as do various automatic tests on things like RCDs, measurement of earth electrode resistance for a TT installation, check loop impedances on live circuits etc. It also stores all these measurements and will download them to a PC, so it makes doing routine testing a doddle, as all you need to do is note the order in which circuits were tested, and then use the downloaded data to generate the numbers for the certificate.

Sadly, even a cheap MFT is several hundred pounds, and the better ones are not much change from £1k, so they aren't really the sort of thing a DIY person may typically bother to buy. I keep test gear mainly because, prior to the introduction of Part P (in England and Wales,) I could legally do all our electrical work, and that for friends and family.

Since then I've used it mainly for doing safety checks, both on our own installation, and that of friends and family, but also on a voluntary basis for those unable to afford to get these done. Every house should have an Electrical Installation Condition Report (EICR), used to be called a periodic inspection, done no more than every 10 years, and ideally every five years now that many installations have RCDs. RCDs need to be self-tested at least once every 6 months, although the self-test doesn't fully test the thing, and they can fail such that they still seem to work when self-tested with the button.

The worst stuff I see is probably portable appliances that have been misused, had new plugs badly fitted etc. Next worst is bodged DIY, or just plain unprofessional, wiring alterations made to domestic installations. It's really pretty rare to find any house that's more than a few years old that doesn't have some dodgy wiring, probably a consequence of someone buying stuff from one of the DIY sheds and just installing it without enough knowledge to ensure that the work they have done is safe. Given the high cost of test equipment, it's not likely that many DIY installations are ever tested properly, either.

 

[rotor2k]

Just to clarify, when you say 500V test, is your test equipment generating 500V? Isn't that super dangerous?

 

[Glan gluaisne]

Just to clarify, when you say 500V test, is your test equipment generating 500V? Isn't that super dangerous?

Yes, it does generate 500V for a few seconds, and yes it will give you a bit of a nip if you touch the live connections during the test!

The secret is to NOT touch the test lead tips when pressing the test button...

 

[rotor2k]

The answer is NOT to touch the test lead tips when pressing the test button...

Haha!

Genuine question: could you measure how many electricians have died from shocking themselves with the 500V test, vs how many people have died from equipment that didn't have the 500V test? In other words, is the test more dangerous than just not doing the test?