Author Topic: I accidentally shorted live with neutral. Did I damage something?  (Read 1016 times)

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Offline HeisenTopic starter

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Hey guys,

I have a very old APC UPS (RS 1000) with no batteries installed. It has a surge protection socket at the back. My intention was to use it for an oscilloscope I am about to buy. Where I live the mains voltage is not that stable. So I ended up testing it with my multi meter. I switched on the UPS put my leads in the live and neutral at the back and I heard slight buzzing/squealing noise, when I looked at my multi meter it was on continuity |O. My house circuit breaker wasn't tripped.

After that I measured with the correct way and it works fine. Tested with the load works okay.
So the short was for around 3-4 seconds before I realized. Could there be any damage to the UPS? Can I use it for my oscilloscope?

Thanks. 
 

Online Jeroen3

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Re: I accidentally shorted live with neutral. Did I damage something?
« Reply #1 on: January 15, 2020, 08:35:35 pm »
Any decent UPS has some overload protection. Single shot, like a fuse. Or resettable by a thermal/magnetic breaker or electronic circuit.
This looks like a decent UPS, and it has an overload LED. Damage to the UPS is unlikely.

Your multimeter on the other hand...
 
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Offline HeisenTopic starter

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Re: I accidentally shorted live with neutral. Did I damage something?
« Reply #2 on: January 15, 2020, 08:47:52 pm »
Your multimeter on the other hand...

Working Okay.  :-DMM
 

Offline bdunham7

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Re: I accidentally shorted live with neutral. Did I damage something?
« Reply #3 on: January 16, 2020, 04:46:52 am »
The continuity setting isn't a short--current would be a short--and many meter are pretty well protected even on continuity.  If you want to blow things up properly you'll have to use the AMPS function.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
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Offline tkamiya

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Re: I accidentally shorted live with neutral. Did I damage something?
« Reply #4 on: January 18, 2020, 11:45:43 pm »
Yup, everything should be fine.  Lucky you because if your multimeter was on lower OHM measurement or current measurement, it would have either damaged the meter or melted the fuse inside. 

Even if that happened, current was in order of milli-amps.  There is no way UPS could be damaged.

I've done that kind of thing many times.  I have several cheap meters for times I'm not so sure what I would encounter.  Nice bench meter comes out only when I'm sure what I'm looking at, or when accuracy is required.
 


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