Why did test lamps show 0V between live side and dead side?

[sparkybooth]

I removed a fuse and before reinserting did the following tests using test lamps. Live side - Neutral = 230V, Dead side - Neutral = 0V, Live side - Dead side = 0V.
I then used a multimeter to check these results as I was expecting a potential difference of 230V between Supply side and dead side.
I got Live side - Neutral = 230V, Dead side - Neutral = 15V, Live side - Dead side = 230V.
Why did I get 0V Live side - dead side using test lamps, but get the expected 230V when using a multimeter?

 

[littlespark]

You don’t test between the two sockets of a fuse.

Doing this with a load on the circuit passes the current through your test device as if it was part of the circuit.

 

[Lucien Nunes]

This was revealing the difference in sensitivity and input resistance between the multimeter and the test lamp. When connected between live and dead side of tbe fuse, the test device is in series with the load forming a voltage divider. The fraction of the total 230V supply that the test device sees depends on the ratio of its resistance to the total.

The test lamp had a much lower resistance than the load (at the moment of test) and saw negligible voltage, i.e. most of the 230V existed across the load and the stray capacitance of the circuit. The multimeter had a much higher resistance and saw effectively all of the 230V, with hardly any of it dropped across the load.

Then with the multimeter connected Load - N, even the stray current on the circuit induced presumably from other live circuits nearby, was sufficient to register 15V. The test lamp's low resistance shunted this without registering any visible reading.