Is it safe to wire separate plugs to two devices previously wired to the same plug?

[Strawberryman]

I have an old hifi system that has a record player stacked on top of an amplifier. Weirdly, both are wired to the same plug. I don't know whether they came like this or whether somebody did it post purchase for some reason (I inherited it from my grandma). I want to pass the record player on so I decided to wire them to separate plugs. However, when I opened the plug it became apparent that only the record player has an earth wire. So, my questions are:
1) In this setup, would the record player's earth wire have been acting as an earth for both devices?
2) how can I know if it is safe to wire the amplifier to its own plug without an earth and keep using it? It is a JVC R-S55L Digital Synthesiser Stereo Receiver

Thanks!

 

[Lucien Nunes]

No equipment would be supplied with two items wired to the same plug This was done by the purchaser perhaps because there weren't enough sockets, it's poor practice because the two cables aren't always effectively clamped.

The amplifier is of class II construction and doesn't need an earth. This is shown by the square-in-a-square symbol on the rating label on the back (check for it!)

The turntable may be class I and needs its earth for safety, but a more likely scenario is that it is also class II and has an earth only for functional reasons, to minimise electrical noise getting into the sensitive pickup wiring and onto the audio. It would not serve reliably as a safety earth for another connected piece of equipment, as the interconnection is not rated to withstand mains fault currents. Indeed the earth might not connect to the phono lead grounds, but only to the deck chassis and arm.

FWIW some turntables avoid the mains earth by providing a separate ground lead alongside the two phono leads connecting to the amp. That way if neither unit has a mains earth, they still agree on a common reference potential and that does nearly as good a job at keeping the interference at bay.

 

[Strawberryman]

No equipment would be supplied with two items wired to the same plug This was done by the purchaser perhaps because there weren't enough sockets, it's poor practice because the two cables aren't always effectively clamped.

The amplifier is of class II construction and doesn't need an earth. This is shown by the square-in-a-square symbol on the rating label on the back (check for it!)

The turntable may be class I and needs its earth for safety, but a more likely scenario is that it is also class II and has an earth only for functional reasons, to minimise electrical noise getting into the sensitive pickup wiring and onto the audio. It would not serve reliably as a safety earth for another connected piece of equipment, as the interconnection is not rated to withstand mains fault currents. Indeed the earth might not connect to the phono lead grounds, but only to the deck chassis and arm.

FWIW some turntables avoid the mains earth by providing a separate ground lead alongside the two phono leads connecting to the amp. That way if neither unit has a mains earth, they still agree on a common reference potential and that does nearly as good a job at keeping the interference at bay.

Hi. Thanks very much for the thorough response. That's very helpful, and interesting!

 

[littlespark]

My dad used to do this… not an electrician of course.

Turntable and hifi on same plug…. Tv and vcr on same plug….

It was just him not needing to go buy an adapter as we only had single sockets at the time.

 

[Strawberryman]

My dad used to do this… not an electrician of course.

Turntable and hifi on same plug…. Tv and vcr on same plug….

It was just him not needing to go buy an adapter as we only had single sockets at the time.

Interesting. Yes, I can well imagine my grandad or uncle having done it. I actually thought it was quite impressive how they managed to squeeze so many wires in one plug!