11-02-2015, 09:46 AM
The RCD is useless in your setup. If it's on the primary of the TX, it won't "know" about any earth leakage faults on the secondary. If it's on the secondary, unless somewhere on the secondary winding is earthed before the RCD there cannot be any imbalance for it to detect.
You may regard your own safety as optional but let's make it abundantly clear that yours is not an example to follow. For those without specialist knowledge the guidance given by Mark and in the BBC document are the safest methods. RCD on bench, isolating TX for working with a single specific item when you want to connect earthed testgear.
There is no panaea, there always ways to hurt or kill yourself. The first and most important item is to be aware of possible dangers and work accordingly. RCDs and isol TXs are a secondary level of protection. For example consider the HT supply in a radio with a proper mains transformer and earthed chassis. This will be at 200V to 300V above earth and it will give you a nsaty belt if you touch it. Neither RCD nor isol TX nor fuse will give you any protection in this situation. 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.
You may regard your own safety as optional but let's make it abundantly clear that yours is not an example to follow. For those without specialist knowledge the guidance given by Mark and in the BBC document are the safest methods. RCD on bench, isolating TX for working with a single specific item when you want to connect earthed testgear.
There is no panaea, there always ways to hurt or kill yourself. The first and most important item is to be aware of possible dangers and work accordingly. RCDs and isol TXs are a secondary level of protection. For example consider the HT supply in a radio with a proper mains transformer and earthed chassis. This will be at 200V to 300V above earth and it will give you a nsaty belt if you touch it. Neither RCD nor isol TX nor fuse will give you any protection in this situation. 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.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
