The setup was somewhat different from usual. Rather than me playing electric guitar and being led by our usual worship leader, with his vocals and all-singing keys (which can provide drum sounds and bass sounds) he was absent and I was leading on electro-acoustic guitar and vocals.
We (sadly) don't usually have any foldback whatsoever. However, on Sunday I took my wedge monitor, which was fed with a mix of my electro-acoustic guitar, my mic and my wife's mic:
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Mic1 ==> DI_1 ==> Snake ==> FOH || ||==> Ch1 of on-stage mixer || || || ||==>Sole wedge monitor || || ||==> Ch2 of on-stage mixer || Mic2 ==> DI_2 ==> Snake ==> FOH Electro-acoustic ==> DI_3 ==> Snake ==> FOH || || ||========> Ch3 of on-stage mixer ==> Sole wedge monitor
For info, the FOH mixer is a Peavey 18 channel thing, and would have had phantom power enabled, in order to power the DI boxes, which are Behringer DI-100. The mics are Sennheiser dynamics.
Although I've consequently purchased an RCD, and resolved always to put it between my 4-gang power adapter and the wall socket, there is surely still an electrical fault somewhere. I haven't yet assimilated all of the mic shocks sticky post found within this section of the forum, but our church minister has been informed of the issue.
This evening I tested for continuity between the chassis of my mixer and the earth pin of its main plug. No continuity. The manual states "This product is equipped with a 3-wire grounding type plug; this is a necessary practice to prevent electric shock hazards to the operator, the microphone user, and the musicians who are wired to this unit." Nonetheless, taking the mains plug apart I found only two wires; one connected to live, one to neutral and nothing connected to earth. Further inspection yielded the double insulated symbol on the Phonic power supply that came with the mixer. Presumably that part of the manual is incorrect, perhaps having been copied from the manual of an older model.
I'd appreciate your thoughts on the above, and your wisdom in identifying next steps in the investigation. I can think of several, but don't have the expertise to know how to prioritise them (and I'm sure there will be additional steps to take):
- Testing for a good connection from the wedge monitor to earth. However, I don't know what exposed part of the wedge, if any, ought to be at earth potential.
- Testing the earth connections of the other components.
- Another church member has a device which can be used to test the room's mains sockets.
- Testing my 4-gang power adapter's earth.