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BANGKOK 21 November 2018 02:39


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About Crossy

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  • Birthday 04/04/1958

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    Pathum Thani, LoS

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  1. Crossy

    MOVs in an outdoor outlet

    AliExpress have them from various sellers @ USD 0.40 - 0.50 a pop (search for "varistor S20K275"). How many do you need (I still have a few left)? Or the S20K250 should be fine. The S20K230 would likely be marginal on voltage rating.
  2. Crossy

    MOVs in an outdoor outlet

    Taking on board @maxpower's much appreciated comments we have this:- All the bits were "in stock" in the assorted stuff box (never throw anything away). The bolt next to the MOVs is blocking up a hole which I thought was a bit big to maintain integrity should the MOVs fail. A few small holes wouldn't be a big issue, indeed they could serve to let the "magic smoke" (smell of frying MOVs) out to alert you to their failure. Of course, this being Thailand the ground wire is brown (and bolted to the metal box) thus maintaining the black and white L and N convention. In reality I wouldn't bother for an outdoor outlet in a block wall or inside a mostly metal and glass light fitting (all our circular "used to be fluorescent but now LED" fittings have these MOVs on the incoming choc-bloc). But if you're going to have it in your lounge or other valuable places go with the metal box.
  3. What do Ford have to say about their OEM tyres failing so quickly? Even thumping a pothole at speed shouldn't cause things to de-laminate. Does the EV have a "real" spare? Bung it on and put the iffy one as spare (assuming it's holding air).
  4. Crossy

    MOVs in an outdoor outlet

    Bloody good point
  5. Crossy

    MOVs in an outdoor outlet

    I'm persuaded Since we probably don't want to do this, do you have a recommendation for a suitable thermal fuse that can be sandwiched between two 20mm MOVs? Ideally readily available here, if not then AliExpress or the like. EDIT Something like this? https://www.aliexpress.com/item/TF-Thermal-Fuse-10A-250V-Temperature-65C-85C-100C-105C-100C-113C-120C-130C-152C-165C/32893092186.html The 65C units would likely do the trick if the enclosure isn't getting too warm in operation. At 14 cents a pop we probably should be doing this. Is it worth glueing the fuse to the MOV?
  6. For the sake of everyone, could you provide a reference or link to the actual law.
  7. I did say "(one assumes)" That said. In the days before they farmed out the visa business I had cause to visit the consular section of the British Embassy on a number of occasions. There was invariably a fellow countryman with "two bagger" (one for you in case hers comes off) in the visa application line. Evidently beauty is in the eye of the beer-holder.
  8. Crossy

    MOVs in an outdoor outlet

    Fun eh? It is most definitely true that prolonged over-voltage does cause MOVs to overheat and potentially catch fire. It is also important to understand that these devices do wear out if subjected to many (should be thousands) surges and the wear out mechanism is a progressive reduction of the trigger voltage. So the scenario could indeed occur. At least in theory they are supposed to pop apart and go open circuit. If you are going to put these chaps behind outlets, make sure there are metal back boxes and I would avoid wooden walls. That said, these things are all over the place including in "surge arresting" power boards and plug-in arrestors. None of these that I've seen have any form of protection against the MOV going short, so one assumes they just catch fire (I've never seen one go like that). Of course, if you do add a fuse, you don't know if the protection has failed unless the fuse also cuts the power to the outlet. For our OPs application behind an outdoor outlet I would just do it. If you're building your own extension boards add a 5A fuse to the inlet side (before the MOV), that should open if the MOV fails and still let you have a kW of connected load.
  9. Crossy

    MOVs in an outdoor outlet

    Pretty much. As I noted earlier the 8kA beasties are cheap enough to do a full 3-leg job although most "surge supressors" do only have one (tiny) MOV L-N.
  10. Check your mobile data really is completely disabled. Even tiny amounts of data can swallow your balance if you don't have a data plan. Failing that time to visit a DTAC outlet and see what they say.
  11. Crossy

    MOVs in an outdoor outlet

    I bought a bag of these chaps http://www.mynpe.com/mynpe/more.php?data=116450101007 8kA rating, 12 Baht a pop from NPE. Datasheet S20K275.pdf In your outlet connect three, L-N, L-E, N-E. Sleeve the exposed leads. Since you have a long run it may be a good idea to bash in a local ground rod and not use the ground in the cable (if there is one). This is what I did when our gate controller got fried by a surge. The supply run is about 60m, easily enough to pick up nasties on it's way from the house.
  12. I wouldn't travel without one. The one time my girlfriend (now wife) had problems (not immigration, lost bag) whilst airside was the one time her phone was out of battery. Cost us a load of hassle and time (but no money).
  13. A (one assumes) relatively young, attractive Thai lady travelling alone sets just about every flag that a UK IO has available, it really can be like entering a high security zone. Smart move, I hadn't thought of using a UK SIM
  14. @wgdanson why "confused"? Our OP didn't mention that his lady would have either a mobile or his mobile number.
  15. It could be low voltage, but without a meter (yes, it is a meter, a metre is a unit of length) you're not really going to get far. That said, all our LEDS are good down to 90V, so if it's really that bad you may well have noticed other issues. Digital multimeters can be had for a few hundred Baht, even Tesco have them.