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This question already has an answer here:

My multimeter is rated for 600V but I need to measure a 10kV AC source. I was thinking of building a voltage divider but I wouldn't know how many resistors it would take to safely measure this high of voltage.

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marked as duplicate by JYelton, Elliot Alderson, Huisman, Renan, evildemonic Jul 3 at 20:11

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • \$\begingroup\$ @JYelton I have read that thread and that is why I was inclined with building a voltage divider however the amount of resistors needed to build a divider that would work in this scenario I am unsure of. \$\endgroup\$ – user225747 Jul 3 at 17:51
  • \$\begingroup\$ The second answer to the duplicate thread tells you exactly how many resistors and of what value are needed. \$\endgroup\$ – Elliot Alderson Jul 3 at 17:55
  • \$\begingroup\$ The second answer of Measure high voltages with a multimeter is poor... it doens't account for the mismatch of resistors' capacitance: this is AC! Better read A way to measure unknown high voltages with an oscilloscope \$\endgroup\$ – Huisman Jul 3 at 18:06
  • \$\begingroup\$ @Huisman - if you are referring to my answer, the probes say they are good for 60 Hz. Agree, they are no good for higher frequencies. \$\endgroup\$ – Mattman944 Jul 3 at 18:23
  • \$\begingroup\$ @Mattman944 No I was commenting on Elliot Alderson's remark: The second answer to the duplicate thread is poor. \$\endgroup\$ – Huisman Jul 3 at 18:31
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10 kV AC is measured using a voltage transformer.

enter image description here

Figure 1. Source: gfuve.com.

The Model GFJDZX0978-10BG voltage transformer is single-phase multi-winding whole sealing epoxy pouring product. It is used both indoor and outdoor for measurement of voltage and electric energy as well as relay protection in the electric system of rated frequency 50/60Hz and rated voltage 12kV or below.

10 kV measurement is not something you do with a few 1/4 W resistors and a hobby multimeter.

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  • \$\begingroup\$ so you're saying it can't be done or shouldn't? \$\endgroup\$ – user225747 Jul 3 at 17:55
  • \$\begingroup\$ @wofeji Not if you want to live. \$\endgroup\$ – DKNguyen Jul 3 at 17:58
  • \$\begingroup\$ If it's a 10 kV battery powered electric fly-swat you're probably OK. If this is medium voltage mains power then you don't go near it. I've seen how this stuff is properly terminated. It's big, bulky and expensive. \$\endgroup\$ – Transistor Jul 3 at 17:58
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You can easily make a 50kV probe for free (surplus/scrap junk yard) or

specs=?

Depends on your Probe Load R specs. Typ. 1000:1 probes are designed for 100 M, which you can make with a string of 500V or 1kV cheap resistors inside a polycarbonate tube with polycarbonate hand shield.

Using rubber wire tip >10cm from hand position

Alligator clamp for ground to Blk wire.

But all sources of grid power at >=600Vac have Arc Flash minimum distances with fire protection gear , so,I trust this is not your goal.

I have measured 200kVac using a very large size low pF Cap transform to low voltage. This works better than a voltage transformer.

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  • \$\begingroup\$ Make a precision parallel-plate capacitor, to provide 1uA into the 10MegOhm of the DVM. At 10,000 volts and 377 radians/second for 60Hz, you need C = I / dV/dT = 1e-6/ [10,000 * 377] or about 1/3 picoFarad. How precise must you measure? or this just a relative-change monitoring? \$\endgroup\$ – analogsystemsrf Jul 4 at 5:22
  • \$\begingroup\$ Yes in HVAC bushings they do exactly this with a porcelain(glass) gap capacitor to external LV cap \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 4 at 5:24
  • \$\begingroup\$ Or you can get Mica caps rated to 30kV about 3cm long. (That’s What Tesla used.. 99.9% pure Mica) \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 4 at 5:30
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You can buy a HV probe for your DMM. Fluke 80K-40 High Voltage Probe. https://www.amazon.com/Fluke-80K-40-High-Voltage-Probe/dp/B000LDQ672/

If you are a hobbyist this might be more than you want to spend, but how much is your life worth? Please don't fool around with building your own voltage dividers at this voltage unless you really know what you are doing.

Here is a less expensive model. B&K Precision PR 28A High Voltage DMM Probe, 40kV, X1000 Attenuation: https://www.amazon.com/Precision-PR-28A-Voltage-Attenuation/dp/B004PA02Q8/

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  • \$\begingroup\$ This is the same answer as the accepted answer for the duplicate question. And your links will be dead and useless if Amazon changes its listings...the necessary information should be part of the answer itself. \$\endgroup\$ – Elliot Alderson Jul 3 at 18:11
  • \$\begingroup\$ Sorry, I answered before it was flagged as a duplicate. The first sentence does say a HV probe for your DMM. And I listed the Fluke PN. I will edit to list the PN for the other example. \$\endgroup\$ – Mattman944 Jul 3 at 18:18
  • \$\begingroup\$ I flagged at 2019-07-03 17:38:46Z, this answer posted at 2019-07-03 17:58:42Z. \$\endgroup\$ – JYelton Jul 3 at 18:21
  • \$\begingroup\$ I will delete if this is bothering you. \$\endgroup\$ – Mattman944 Jul 3 at 18:26