If I have a 1kV DC circuit, does the ground wire need to be rated for the full 1000V?
The circuit is pretty simple, two wires from a power supply to a resistive load.
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\$\begingroup\$ The ratings depend on the application and size of power source but I suspect your power is tiny. Ther ground insulation properties depend on a ground fault open cct. And how likely that may occur. \$\endgroup\$– D.A.S.Commented Sep 5, 2019 at 20:47
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\$\begingroup\$ You might want to consider SHV connectors/cables, depending on what your system looks like pasternack.com/… \$\endgroup\$– llamaCommented Sep 6, 2019 at 15:35
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\$\begingroup\$ Presumably when you say "ground" you mean the common lead (ie: the normal return path for the current) and not a bonding wire, safety ground, etc(?) \$\endgroup\$– J...Commented Sep 7, 2019 at 17:18
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2 Answers
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Consider this:
You have your 1kV power supply, with an impressively insulated wire going out to a resistor. Coming back, you have a return wire with light insulation because, hey, it's grounded!
Now the ground wire breaks at the power supply.
Your "safe" ground wire is now at 1kV. Is that light insulation sufficient?
answered Sep 5, 2019 at 19:58
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7\$\begingroup\$ Also, if you're working with 1kV voltages and don't immediately know the answer to this question, I think you probably should be seriously considering stopping the project right now and taking some time to study. This isn't the kind of lesson you want to learn the hard way, and with kV scale power there are a myriad of hard lessons that are just waiting for someone to murder. \$\endgroup\$– J...Commented Sep 6, 2019 at 15:10
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1\$\begingroup\$ @J... The op wrote "If.. ". So clearly it's an academic/ genuine question. Why the sarcasm...? \$\endgroup\$ Commented Sep 7, 2019 at 16:35
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1\$\begingroup\$ It is not intended as sarcasm. It is intended as Socratic question, to provide a thought framework for the OP to find the answer themselves. \$\endgroup\$ Commented Sep 7, 2019 at 16:58
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\$\begingroup\$ @Soldersmoke I wasn't being sarcastic. It's genuinely hazardous to be designing, building, modifying, or hacking high voltage equipment or circuits without the prerequisite understanding of how to safely and correctly do such work. My comment is there as a cautionary statement - that OP really needs to be careful working with kV power, particularly given that they're already into said system and have demonstrated, with their question, that they do not have a sufficient understanding of electrical safety. If they did, they wouldn't need to ask such a rudimentary question. \$\endgroup\$– J...Commented Sep 7, 2019 at 17:16
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\$\begingroup\$ @Timwescott ah yes, Socratic. I think I too will try those on this forum, based on your lead. Should be fun. Thanks ! \$\endgroup\$ Commented Sep 7, 2019 at 17:20
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If the 1kV is AC, the peak voltage may be even 1,4 KV. If the power supply ground is on the same reliable ground as the resistor which is grounded directly at one end (f.e. one common metal casing for power supply and resistor), the ground wire does not need any isolation at all resp. the ground "wire" is the metal casing that does not have an insulation. The high voltage in a microwave oven of 2000 resp. 4000V is grounded at one side at the metal casing which is connected to PE. Only the insulation of the other "hot" wire coming from the high voltage transformer is rated for that high voltage.
But - as mentioned in the first answer - if the ground could be interrupted, both wires must be insulated for the high voltage. For a metal casing of a MW, it is highly unlikely - if not impossible - that the metal casing will be separated by fault in a way to endanger the user with high voltage. There would be leaking MW radiation as well.
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\$\begingroup\$ I would not design such a supply to be referenced to earth ground. Rather, I would have the supply floating from ground. \$\endgroup\$ Commented Sep 6, 2019 at 22:23
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\$\begingroup\$ Too many "if's" I'm your answer. Lost you after just 2 sentences \$\endgroup\$ Commented Sep 7, 2019 at 16:38