On 02/06/2019 12:52, Cursitor Doom wrote:
On Sun, 02 Jun 2019 11:03:03 +0100, Jim K.. wrote:

How much should the op spend on a "proper multimeter" to do the
job properly?

You don't have to spend a fortune. I use one of these for anything to do
with the mains: https://tinyurl.com/y49d475v

But cheaper still options are available.

The Fluke 101 could be worth considering. Joe Smith ran a series of high
voltage tests on a range of "cheap" (under 50 USD) multimeters and this
was a clear winner after testing up to 13 KV.
https://www.youtube.com/watch?v=RBkjr3b5hQo

Officially this isn't available in the UK but can be found from
apparently reputable UK suppliers on Ebay for under £50.

It has rather limited features so might not meet everyone's needs. In
particular it does NOT measure current but this has the advantage that
there's no danger of putting it across the mains with the leads in the
'amps' socket because there isn't one.