Isolation transformers, use of.

[Nick]

Counter-intuitively the HT rail on a live chassis set can be safer if fed via an RCD as it will trip before you get a serious shock.

This is all good stuff, but its worth also noting that there are RCDs.... and then there are RCDs...

A few things - check your RCD regularly - I find that in the slightly humid conditions of my workshop cellar, an RCD typically only lasts about 3 years before it starts to become erratic and thus needs replacing. Use the test button. Regularly!

Further, if you have an RCD rated for 30mA you will still get a blast for up to 30mS, which for some of our more senior or frail members may be problematic, i.e. other current ratings are available...

Additionally, RCDs do not protect against over-current, i.e. phase-to-phase or phase-neutral faults (depending on usage of single or multiple phases), so ideally use an RCBO which is an RCD with over-current detection in a single package.

Also, RCDs are vulnerable to a supply-side neutral fault or disconnect that would leave the live side connected, thus they should ALWAYS be connected to the supply via a two-pole breaker - the live must be disconnected at the same time as the neutral.

Best idea in a workshop I've found is to use a consumer unit that has a two-pole breaker with an RCBO, and then MCBs for each spur. Thus EVERYTHING is protected, including those silly times when I run an extension cable to power my saw bench when it's moved into the garden because I'm machining a piece of 8x4 that won't fit in the shed !

FWIW, I use a medical isolation transformer, an ISB60 http://www.toroidtech.de/transformer_pro...Series.htm, which has multiple outlets...

EDIT: We should all be working to "IEE Wiring Regulations 17th Edition : (BS 7671: 2011)" anyway, and not trying to re-invent the wheel...