Brymen BM235 10A fuse silently destroyed by a switched off UPS leakage current.. - Page 1
Forum section: electronics / beginners

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 01:25:37 pm
content: Hi,I have a Raspberry Pi plugged in a UPS which I switch off when not used.Recently I've noticed that the power on led of the Raspberry blinks and fadesaway every 5 seconds with the UPS switched off.I measured ground to live and ground to neutral on the UPS output socketand they show 229V!..Is this normal?Should I throw the UPS in the bin?When I switch on the UPS the connected devices work normally.I've tried to measure any leakage current to ground and the BM235 showed nothing, instead itstarted showing 'DIODE' when I connect the leads.. I took off the 10A fuse and it shows no continuity!Like its damaged. I doubt that more than 10A passed from live to ground on a switched off UPS.The fuse looks new, no explosion were heard, no sparks were seen.How is this possible ?Thanks.

author: Cnoob
author_rank: Regular Contributor
timestamp: March 05, 2019, 02:31:53 pm
content: You UPS may have your neutral isolated from your earth unlike true mains mine reads 247VAC between Live and Earth and 1.8VAC between Neutral and Earth which is a ghost voltage (induced Voltage).As for anything wrong with your UPS I don't much about them but it doesn't surprise me you are reading mains level voltages between your earth live and neutral.But your RPI is connected to your UPS by a USB connection and that's where your fault could be. leaky capacitors seem to cause problems a lot more now.As for your Meter, They don't have a manual on TME and my BM257 manual doesn't say anything about blown fuse indication, but I am going to take the fuse out of it and connect it inline in a circuit.

author: Cnoob
author_rank: Regular Contributor
timestamp: March 05, 2019, 02:53:54 pm
content: I took the out the 11amp HRC fuse the meters display read zero amps or as good as damm it.So I took the 400milli Amp HRC set the meter on milli amp range and plugged lead in Milli/micro circuit back onstill read zero current flowing.It could be a feature of your meter or something is wrong.

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 02:59:37 pm
content: The Raspberry Pi 3 is connected to the mains output of the UPS with its own power adaptor.Its not connected via USB.The fuse does not show any continuity. Its toast.I am at a loss how this fuse got damaged by connecting it from live to ground of the UPS !!

author: Cnoob
author_rank: Regular Contributor
timestamp: March 05, 2019, 03:14:16 pm
content: First off then your power adaptor is at fault.Second if you connected Live to ground/earth with your meter set and connected to measure current (Amps) then you shorted it and that would cause the fuse to blow. But If you were measuring voltages then it would not be the cause of your 11 amp fuse to blow.It isn't unknow that fuse just seem to go open circuit without a specific cause.

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 03:20:01 pm
content: I've connected live to ground while the UPS was plugged in on mains, but switched off.This is supposed a quality fuse that can stand at least 10 Amps for some time.The house RCD would have tripped for just a few milliamps.

author: stj
author_rank: Super Contributor
timestamp: March 05, 2019, 03:24:25 pm
content: the rcd wont trip, the output is isolated from it.the output may be spiking because of the battery monitoring circuit.if you had a scope you could see if it's very short pulses.

author: IanB
author_rank: Super Contributor
timestamp: March 05, 2019, 03:26:34 pm
content: A UPS is an "uninterruptible power supply". In other words it is not designed to be switched off when something is connected to it, because that would interrupt the power to device. I think you might be using it in a manner not consistent with its design.Secondly, it might be that the UPS has some kind of capacitor in the output stage, and if this discharged through a short circuit (a meter in the amps range is a short circuit) then it could easily blow a fuse.I would recommend you unplug devices from the UPS when it is not in use.

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 03:33:13 pm
content: This is a very simple and cheap UPS. Are you sure that the output is isolated from mains?"I would recommend you unplug devices from the UPS when it is not in use."That is the way that you use your devices in a blackout though...Maybe an output capacitor blew the fuse. This is not your usual fuse though.There was absolutely no sparks or noise. Strange.When I connected only the first lead of the multimeter to the UPS live,it started doing a thing like autoranging, bust fast.

author: IanB
author_rank: Super Contributor
timestamp: March 05, 2019, 03:39:25 pm
content: Quote from: hgg on March 05, 2019, 03:33:13 pmI don't think you understand. In a blackout, the UPS is supposed to provide full mains power on the output from its internal battery. In other words, devices are meant to be plugged into it when it is switched on, not when it is switched off. What would be the point of having it, otherwise?QuoteIt's pretty certain that full mains power from the output would blow the fuse...(Under no circumstances should you ever connect a DMM to a power output socket while the DMM is set to measure current.)

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 03:46:03 pm
content: "In other words, devices are meant to be plugged into it when it is switched on, not when it is switched off"I understand. The UPS has a switch off though and I have not read anywhere that you should not switch it offwith the devices plugged in."(Under no circumstances should you ever connect a DMM to a power output socket while the DMM is set to measure current.)"Maybe you did not understand.I connected the DMM between live and ground to see if there was any leakage current.Is there a capacitor connected between live and ground inside the UPS?

author: Cnoob
author_rank: Regular Contributor
timestamp: March 05, 2019, 04:18:01 pm
content: QuoteWithout seeing the circuit we don't know.As you said it's cheap, one cost cutting exercise is the use of autotransformers.And you found out the hard way not to use a meter too short out the Live to Earth.

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 04:21:26 pm
content: I guess you are both right.I've shorted live to earth...

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 04:32:35 pm
content: I did not expect to be any current though with the UPS switched off.That fuse is a beast. I had a very hard time breaking it open with pliers!Maybe that is why it was so quite. The only thing I can see is someblack grains.Is there any remote possibility that this would be genuine ?https://www.ebay.com/itm/Bussmann-DMM-B-11A-1000V-DMM-11A-Multimeter-Fuse-for-Fluke-87-V-88-V-287-289-179/261536107575

author: Cnoob
author_rank: Regular Contributor
timestamp: March 05, 2019, 04:46:37 pm
content: I suspect those ebay fuses are too cheap But I will leave it up to you.If you want to measure earth leakage put the meter inline with earth wire or use a clamp meter.Rule of thumb (but not always) measure current on the low side/return.

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 04:54:35 pm
content: Indeed.I measure leakage with a clamp meter.In this case the UPS was off, it could not power on any device, apart from the blinkingled of the Raspberry barely, and I was curious to see why there was 230V betweenground and live and ground and neutral but with no power to turn on even the Raspberry.But in order for the fuse to blow there should have been a capacitor between live andground inside the UPS. Is this even possible? Wouldn't that short the output duringnormal use?I still don't understand how the fuse blew...

author: Cnoob
author_rank: Regular Contributor
timestamp: March 05, 2019, 05:10:56 pm
content: If your earth is connected to part of the UPS circuitry, then there is your potential current path.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 05, 2019, 05:40:27 pm
content: A extension mains socket or single socket with included switch either for testing or turning off all loads when UPS is completly powered off is also suitable.

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 05:51:58 pm
content: UPS OFFGround - Live : 230VGround - Neutral : 230VLive - Neutral : 0VI've connected an incandescent bulb between live and ground and the house RCD tripped.The UPS does not isolate mains when switched off but it cannot also power anything fromlive to neutral. I have two devices connected. A 3D printer power supply which is earthedand the Raspberry Pi with its power adapter which is not earthed. The Raspberry powerON LED switches on and fades off every 5 seconds, only when one of its USB ports is connectedto the grounded 3D printer. So it looks like its a kind of grounding issue.I think I will include a main power switch as well.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 05, 2019, 06:05:22 pm
content: QuoteThis is a dangerous move :S You've conected a resistive element between live and ground, so current will flow and RCD trips , probably more current and arcing :S The RCD has a self-test button to check this feature. Use the NCV / EF ( Non Contact Voltage) to check isolation, but some cheap UPS have no isolation , even in the battery terminals .About earth check if not creating ground loops due to bad adaptor for the RPI, or use a 5V power supply that has grounding so the same loads has the same ground from the UPS.

author: hgg
author_rank: Frequent Contributor
timestamp: March 05, 2019, 06:18:38 pm
content: Its a crappy UPS.I will use a mains switch for now and I will buy a better UPS with proper isolation.What is the worst case scenario if the RCD had not tripped?

author: IanB
author_rank: Super Contributor
timestamp: March 05, 2019, 07:02:23 pm
content: Quote from: hgg on March 05, 2019, 06:18:38 pmI'm not sure why you think a UPS is meant to provide isolation. A UPS is not an isolating device, it is a backup power device. A UPS is meant to be installed and operating 24 hours a day to protect critical equipment that is not meant to be have its power interrupted.You are using a the UPS in a manner not intended. I do not see why a more expensive UPS will be any different. A good UPS should not even have an on/off switch, since that leaves open the possibility of accidentally interrupting the power to the protected devices.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 05, 2019, 08:43:56 pm
content: The idea of mains switch is to use between the UPS and the Loads you want to disconnect, instead of turning off the UPS. Besides the battery if SLAB or AGM needs maintenace charge to avoid wear over the time

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: March 06, 2019, 02:06:54 am
content: Quote from: hgg on March 05, 2019, 05:51:58 pmThat sounds suspiciously like a Y cap issue with the wallwart providing 'half live' leakage current that slowly charges a smoothing cap on the RPi's 5 or 3.3 v rail until there's enough to trigger an on board voltage regulator (buck switching type?) into life to provide a pulse to drive the LED which then discharges the smoothing cap and the cycle repeats over and over (the classic relaxation oscillator effect).With most (likely all) line interactive UPSes, only the Live output is switched from the incoming mains across to the inverter output. The earth and neutral remain connected with the neutral side of the inverter output bonded to the incoming neutral (which is crossbonded in the mains supply wiring to the earth either at the consumer unit or even as far back as the sub-station (or pole transformer or whatever).There's normally a 'disable switch' on a UPS so that when the protected load(s) are switched off, you can still keep the battery pack float charged without risking a pointless discharge of the battery in the event of an outage during times when backup power isn't being called for (and also when you want to move the UPS from one location to another or even put it into temporary storage or transport it across town or county from one location to another - longer term storage requires removal/disconnection of the battery pack).Bearing the fact of the single pole changeover switching in the UPS, it's extremely important that you don't reverse the Live and Neutral connection to the mains supply. The better Line Interactive UPSes actually incorporate mains polarity connection fault detection LEDs to warn of such problems. If you have the Live/neutral reversed, this could readily account for the winking LED via the Y cap in the RPis's smpsu wallwart.

author: viperidae
author_rank: Frequent Contributor
timestamp: March 06, 2019, 02:45:55 am
content: Could be the ups is only switching the neutral line. That would explain the voltages.

author: hgg
author_rank: Frequent Contributor
timestamp: March 06, 2019, 04:28:16 am
content: Quote from: IanB on March 05, 2019, 07:02:23 pmExactly, especially when it has one and does nothing...It gives you a false sense of security when it just isolates between live and neutral.They should have at least put a huge sticker on it with a warning.I've just checked my UPS on my main computer which is a much more expensive unitwith a pure sinewave output and when you switch it off you have proper isolationfrom the mains. Its off. You have to press the power off button for at least 20 secondsin order to switch it off, so you can not turn it off by accident.

author: hgg
author_rank: Frequent Contributor
timestamp: March 06, 2019, 04:48:30 am
content: Johnny B Good:" Bearing the fact of the single pole changeover switching in the UPS, it's extremely important that you don't reverse the Live and Neutral connection to the mains supply. The better Line Interactive UPSes actually incorporate mains polarity connection fault detection LEDs to warn of such problems. If you have the Live/neutral reversed, this could readily account for the winking LED via the Y cap in the RPis's smpsu wallwart."viperidae :"Could be the ups is only switching the neutral line. That would explain the voltages."YES, YES!That was the problem.I reversed the mains plug on the wall and everything works fine now.No mains output when switched off and no blinking LED on the Raspberry Pi.Thank you!!They should specifically mention that this UPS needs a proper live/neutral wiring!

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 06, 2019, 12:25:05 pm
content: Normally that feature is on the manual of the UPS or in the low end model of some know brands, eg, APC surge outlets with small batteries:https://www.apc.com/kh/en/faqs/FA158817/

author: johnkenyon
author_rank: Regular Contributor
timestamp: March 06, 2019, 02:12:03 pm
content: Quote from: Johnny B Good on March 06, 2019, 02:06:54 amEasily retrofittable - wire a red mains neon indicator (with integral resistor) between the incoming neutral and ground., and mount it on the rear or front panel, labelled "L-N reversed" or "P-N reversed"

author: hgg
author_rank: Frequent Contributor
timestamp: March 06, 2019, 05:28:35 pm
content: Not a bad idea at all.I think I will do it.Problem Solved.One question remains though!When I connected the 40 watt light bulb from live to ground the RCD tripped immediately.When I connected the BM235 the fuse blew before the RCD had the chance to trip.The RCD needs less than 30mA to trip, usually 25 to 28 if its in a good condition.So the fuse blew with 230V and less than 30mA for a few milliseconds.Does this make any sense?Was the fuse faulty or is there something I do not understand? (probably..)

author: IanB
author_rank: Super Contributor
timestamp: March 06, 2019, 07:28:54 pm
content: It was a fast blow fuse. Maybe the fuse blew before the RCD had time to act?

author: hgg
author_rank: Frequent Contributor
timestamp: March 06, 2019, 08:23:49 pm
content: Fast blow fuse, but with how much energy?From its data sheet : "Intended to carry 100% of rated current indefinitely." which is 11A.The RCD tripped with less than 30mA @ 230V in a couple of milliseconds.How much energy did the fuse receive in order to blow before the RCD?Its obviously less than the energy received by the RCD.Somebody to do the math?

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 06, 2019, 09:10:37 pm
content: Look at page 2 of the datasheet , the graph and watch the time vs possible Amps on the fuse and compare to the RCD one :http://www.cooperindustries.com/content/dam/public/bussmann/Electrical/Resources/product-datasheets-a/Bus_Ele_DS_1047_DMM-B.pdfEnough energy to prevent further damaged to meter or user

author: IanB
author_rank: Super Contributor
timestamp: March 06, 2019, 09:10:49 pm
content: Quote from: hgg on March 06, 2019, 08:23:49 pmThe RCD willalsotrip with 30 A in a couple of milliseconds. It will trip with 300 A in a couple of milliseconds. How do you know how much current actually was present when the RCD tripped and when the fuse blew? (You said a 40 W bulb tripped the RCD, so that was 40 W / 230 V = 170 mA. Already much more than 30 mA.)Bear in mind that based on the previous comments in this thread where you had the mains polarity reversed, it appears you had the full power of the mains live conductor available to supply current. If you connect that to earth/ground you could expect to see hundreds of amps flowing in cases where the earth conductor is bonded to neutral at the supply.Since you blew a 10 A fuse, you can deduce that much more than 10 A flowed through the fuse at the time it opened.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 06, 2019, 10:11:48 pm
content: The BM235 has low-z mode but be carefull AutoV (LoZ). Check page 7 of its manual .

author: Electro Detective
author_rank: Super Contributor
timestamp: March 06, 2019, 10:32:30 pm
content: Low Z mode is great for stray leakage and confirming capacitive ghost voltages, but will trip the RCD every time, unless DUT is isolated from the mains.FWIW: some meter brands need to cool down (up to one hour) after using Low Z mode on mains voltages,as resistance readings in Ohms mode may not be stable or accurate with the user believing he/she has a lemon meterI've played with UPS units in the past and noticed on some that the input Live and Neutral can be wrongly wired by the manufacturer,especially "international market wiring colour scheme" snafus > black and white vs brown and blue vs red and blackvs drag revue pink and purpleAND I've observed Live and Neutral flipped/reversed on the UPS output during a power outage as referenced to the input sine waveSome can be wired properly so that input and output POLARITY is correct, with some expected voltage/current phase shift difference expectedBy saying 'Some can wired be properly' I mean if the rewire does not affect the battery charging circuit and battery if there are common connections.If the UPS output runs through an isolation transformer, like some APC SmartUPS and similar Compaq/HP IIRC, those are easy to correct -if- they are out of wack.Yes, some are, most not, luck of the draw.Still, their transformer output is isolated (many times via two 120v legs plus CT feeding 240v to L and N output) with earth/ground still connected at the wall socket,so the connected load/equipment won't careAll my blab above assumes correctly wired wall socket/s, IEC kettle cord leads, decent power strip boards,with no moisture or short causing dirt/metal particle ingress anywhere.and non flipped or poorly repaired DIY extension cords (classic widow makers)@ hgg: we may never know if the meter fuse blew because of what happened somehow with the UPS, or from a previous test, a severe meter drop/vibration,or the fuse was a rare dud,or someone borrowed the meter and zapped it with voltage on the current setting, whatever...The good news is that it got you pumped to find out what the go was, and corrected a far bigger problem/issue...than worrying about the euros you will blow on another fuseYES, they are WAY-Y-Y overpriced for what they are,another necessary credit cardrapeitembut still a bit cheaper than buying a replacement meter and or blowing money at a hospital/funeral...and the sellers know itThe sneaky cheaper knockoff fuse floggers aren't doing the electronics community any favours either**** them

author: hgg
author_rank: Frequent Contributor
timestamp: March 07, 2019, 06:29:49 am
content: If I read the fuse datasheet correctly, it can hold 125 Amps for 40ms.The 30mA RCD can hold for the same amount of time 150mA (500% of its rated trip current)The 40W incandescent lightbult had an initial cold resistance of 97Ω, which means thatit drew 2.37Amps when it was connected between live and ground.When the fuse was connected from live to ground it was a dead short (almost)How can we calculate the amperage at the time of the short?The device was connected to a 10A fuse which did not blow.(I am trying to understand because there was not the tiniest spark when I connected themultimeter probes and one probe was barely hanging by itself on the ground terminal.)

author: Cnoob
author_rank: Regular Contributor
timestamp: March 07, 2019, 09:05:57 am
content: QuoteThat could suggest the fuse was already broken.And why the RCD didn't trip it could be that when you shorted it out there was already another current path to complete the circuit.You tripped the RCD with a light bulb, you may have blown a expensive fuse by shorting mains level voltages and you wired up your UPSincorrectly.To me that suggests you should leave mains and mains level voltages alone.

author: Jeroen3
author_rank: Super Contributor
timestamp: March 07, 2019, 09:14:12 am
content: If I switch off my UPS, it goes into bypass mode. Maybe only interrupt neutral indicates a problem inside the UPS?If I want to power down anything behind my UPS, I have to switch if off, and unplug it.

author: dmills
author_rank: Super Contributor
timestamp: March 07, 2019, 11:09:20 am
content: RCDs have TWO parameters, a rated trip current, often 30mA (actually this is a 'must trip' level, they generally go at half of this), AND a trip time....Common examples have a must trip time of 30ms, and will generally go in 20ms.These two parameters mean that there is ample time for a stiff mains supply to eat a 10A fuse and clear the fault before the RCD trips. Yea, sure, 1kA or so of PSC (Could be much higher if close to the incomer and using heavy cables) is way more then 30mA, but if the fuse opens and quenches the arc in under 10ms the RCD will probably not trip because the fault has not been sustained for long enough.You can actually buy time delay RCDs which are usefully deployed upstream of the usual sort as they provide substantial fire risk reduction while still providing the discrimination to avoid tripping the whole installation due to some stupid downstream fault that should just trip the local one. Standard sizes for these are (100mA, 100ms), (300mA, 300ms) and the biggie for large three phase jobs, (3A, 3 seconds).Note that a 30ms delay 100mA RCD does not provide useful discrimination with a 30mA, 30ms RCD because it is a crap shoot as to which one will trip first on a earth fault of more then 100mA.The fuse did its job, and THIS is why meters have expensive fuses on the high current ranges.Regards, Dan.

author: hgg
author_rank: Frequent Contributor
timestamp: March 07, 2019, 12:48:21 pm
content: "1kA or so of PSC" and not even the smallest spark on the multimeter leads?

author: Cnoob
author_rank: Regular Contributor
timestamp: March 07, 2019, 01:52:25 pm
content: I look at Bussmann's graph for that particular fuse which is call a clearance graph of time v current.Assuming I reading the graph right.I'm reading that graph as the time taken for the fuse to clear a fault condition and as this was a short circuit near instantaneous currents are involved. How high ? it depends on your impedance of your voltage source. I think it's safe to assume it's a high current and on the graph. A near instantaneous current of 150 Amps the fuse will act in 15mS. I suspect the fuse could act quicker but Bussmann are erring on caution.So it is quite possible for that fuse to blow before the RCD can trip.

author: dmills
author_rank: Super Contributor
timestamp: March 07, 2019, 03:35:44 pm
content: Yep, RCDs are not (Unless RCBOs) overload sensitive, they will pass a lot of current and merely get hot, overload protection is a different type of breaker.I would expect a LOT more then 150A in a dead short to 'earth' situation assuming TN-C-S or TN-S supplies are in use (TT, the fuse might not even have blown in a week! This is NOT a good thing!).Like I say, THIS is why good multimeters have expensive fuses, quite possible a kA or so flowed, but probably the only part that failed was the fuse, and it kept all the damage contained inside the fuse housing, quite impressive actually.Regards, Dan.

author: hgg
author_rank: Frequent Contributor
timestamp: March 07, 2019, 03:39:54 pm
content: Do you think that not seeing any sparks was expected ?

author: IanB
author_rank: Super Contributor
timestamp: March 07, 2019, 03:52:08 pm
content: Quote from: hgg on March 07, 2019, 12:48:21 pmQuote from: hgg on March 07, 2019, 03:39:54 pmYou tend to get more of a spark when breaking a circuit than when making it. I have shorted 240 V mains a couple of times in the past, and it was not very dramatic. I hardly noticed I'd done it until afterwards, when the fuse had blown or the breaker had tripped. Each time I had just barely touched a live wire against a grounded terminal and that was enough to trip the circuit protection.

author: hgg
author_rank: Frequent Contributor
timestamp: March 07, 2019, 03:55:19 pm
content: So it looks like that all this shows the safety of a good multimeter.I bought 2 of the ebay fuses but I am 99% sure they are fake.I just want to open them and compare them with the original.The original costs a Chinese multimeter..

author: Electro Detective
author_rank: Super Contributor
timestamp: March 10, 2019, 09:51:52 pm
content: Test them to failure (SAFELY) and take notes,then open them up and see how well the fuse housings and materials fared.If 'BS' spec 10 amp fake cheapie fuses blow at 8 amps instead of 10 amps reasonably fast, at a fraction of the cost,they are cheap and sort of do the job for the price, and a better deal than no fuse (or galvanised fencing nail) hey what do you want?If they are labelled 10 amps and blow at 12 or 15 amps, or your meter smokes first,don't waste your cash..and meter

author: rsjsouza
author_rank: Super Contributor
timestamp: March 10, 2019, 10:14:07 pm
content: Quote from: hgg on March 07, 2019, 03:55:19 pmI think that is the most interesting conclusion of all this. Lots of folks argue how idiotic or exaggerated our claims are for meter safety around this forum, but this scenario is a perfect example of how even a CAT I system can be quite powerful when doing a simple measurement.Would an el-cheapo meter or a fake HRC fuse kill you in the same scenario? Probably not, but it would give you a scare at a minimum and (big maybe) injure you if the case couldn't contain the energy.Regarding arc flash on regular outlets, I have had my share of very impressive events on both the typical 15A circuit and some higher ones (40, 80A).

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 10, 2019, 11:00:08 pm
content: I had one cheapo meter exploded while probing mains in Volts a long time ago, which gave a good jump scare (PS this are the older remains stored in garage so there might be some spider webs) : :[Edit here they are detailsDon't blame the spiders it happened well before they nest ...]https://www.eevblog.com/forum/testgear/new-aneng-q1-9999-counts/?action=dlattach;attach=458422https://www.eevblog.com/forum/testgear/new-aneng-q1-9999-counts/?action=dlattach;attach=458389https://www.eevblog.com/forum/testgear/new-aneng-q1-9999-counts/?action=dlattach;attach=458395

author: hgg
author_rank: Frequent Contributor
timestamp: March 11, 2019, 04:54:33 am
content: - "Regarding arc flash on regular outlets, I have had my share of very impressive events on both the typical 15A circuit and some higher ones (40, 80A)."Do you mind sharing the details?- "Test them to failure (SAFELY) and take notes,then open them up and see how well the fuse housings and materials fared."Will do.

author: rsjsouza
author_rank: Super Contributor
timestamp: March 12, 2019, 03:15:29 am
content: Quote from: hgg on March 11, 2019, 04:54:33 amI have shared it in one or two threads around here, but the short version is that, in at least two occasions, if I weren't using glasses I would have vapourized electrolyte and a blend of silicon/epoxy etched to the bottom of my eyes.

author: hgg
author_rank: Frequent Contributor
timestamp: March 13, 2019, 02:21:47 pm
content: johnkenyonThank you for the idea.The UPS already had a covered hole with the exact diameter of a mains neon indicator...This is how it was meant to be made...

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 13, 2019, 11:55:59 pm
content: Nice, and the meter? Get a decent fuse 10x38mm 11A fuse ( Siba, Bussman) for the meter and consider next time using an small extension cord with splitted cables ( earth, neutral and live) to connect a small load ( a 5V usb power cord) and only connect in series the matched color / type r of cable when using current, also consider using a clamp / current AC transducer eg:https://ebay.us/zEtvaFor even a clamp meter such the uni-t 210E.

author: hgg
author_rank: Frequent Contributor
timestamp: March 14, 2019, 04:53:19 am
content: The meter is waiting for the new fuse.I already have both the UT210E and a splitted earth extension cord...

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 14, 2019, 12:36:56 pm
content: Good another thing to explore with the extension cable is leaks between earth-neutral or earth-live, putting these pairs in the clamps, without any load attached.i follow previous post a recomendation for fuses, based on the jpscalibrationservices seller .

author: hgg
author_rank: Frequent Contributor
timestamp: March 14, 2019, 01:28:26 pm
content: He lists shipping for Greece from 11 pounds to 14 pounds which is crazy expensive for little a fuse!Obviously he makes money from shipping as well...

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 14, 2019, 09:11:20 pm
content: Another option maybe is tme:https://www.tme.eu/en/katalog/#search=siba%2011A&cleanParameters=1https://www.tme.eu/en/katalog/#search=bussman+11A&s_field=accuracy&s_order=DESCLook at the price difference

author: hgg
author_rank: Frequent Contributor
timestamp: March 15, 2019, 07:57:59 am
content: TME, thats where I bought the Bussmann fuse. (I am also waiting for 2 ebay fakes..)20 euros! double the price of the SIBA fuse.Am not sure though how the double price is justified...