How can I build my own over voltage protection circuit up to 480 VAC

I am rigging up a portable test panel, will be using a true-meter APM that will do up to 600 VAC or 600 VDC. I would like to be able to use it to measure typical U.S. 120 VAC or 240 VAC and 480 VAC. Looking for recommendations on how to build a simple economical circuit such that a fuse would blow if input voltage exceeds ~500 VAC or 500 VDC.

For 480 VAC, is that RMS so would peak voltage be 679 V and would that matter or make things more complicated in building a fuse-able circuit that would trip? The sole purpose being I'd rather blow a $1 fuse than my$70 volt meter.

• How much current? I've used back to back lnd150's as input protection... good to ~400V, maybe one could put two pair in series? – George Herold Mar 12 '18 at 16:11
• datasheet for apm-volt-apn says the imedance is 1.5 megaohm, so a few milliamps if not microamps. And the max over voltage rating is stated as 800V. – ron Mar 12 '18 at 16:46
• Did you consider ultra rapid cartridge fuses and metal oxide varistors? – Jeroen3 Mar 12 '18 at 18:58
• no i did not, it has been ~20 years since i messed with stuff like this in school – ron Mar 13 '18 at 15:54