Hello, Does anyone have advice or thoughts on how to make old radios electrically safe? i.e. Should the old two core power cord be replaced with a three core power cord with the earth lead connected to the metal chassis of the radio? I also wonder about adding a perforated back cover to prevent children from touching any live parts of and old open back radio.

Paul,
It is LAW here in QLD and I know for a fact elsewhere in Australia & NZ. I recently had an electrical audit done so I can assure you that what your are suggesting is a must. For example the earth cord must be terminated with the bare (not tinned ) wire crimped inside a lug and screwed to chassis with a star washer. You can check all this out just by searching " electrical safety act " Also you MUST be the holder of a Restricted Electrical License if you work on 240 volts AC.
Hope this helped.
Rudy

Rudy, Thanks for the advice. I did get a Restricted Electrical License in NSW about 20 years ago, but never used it. I wonder if it will one day it will be illegal to sell a vintage 240V appliance, like a radio, on ebay or anywhere else without some sort of Electrical Inspection and test certificate? I better go and read the curreent NSW regulations in this area.
Regards,
Paul
greenopaloptusnet.com.au

Paul,
The answer is yes, it is illegal to sell without a tag ,safe or otherwise,but you see them all the time without them. Also here in Qld we have renew our certificate every 5 years.
Regards
Rudy

I've watched this discussion with some interest. This issue probably should become the subject of some information here though it won't be easy as the law is different in each state and territory and these laws do get altered a lot.

It may be that the situation in each state should be summarised and perhaps a list of recommendations based on the strictest clauses in each piece of legislation be drafted. This could then be used as a set of guidelines for everyone.

I think earthing the chassis of an old radio is a good idea though always remember that earthing such a chassis removes the isolating properties of the transformer as the earth wire in your home is binded to the neutral wire at your dwelling's main switchboard. The only way that I can see to maintain isolation when working on a live chassis (and this should only ever be attempted by experienced people for reasons that I will outline in a minute) is to plug the radio into a seperate 240v - 240v isolation transformer. With the advent of RCDs (residual current detectors) or more commonly known as safety switches, isolation transformers are becoming harder to come by so I have no idea where to get one. If you have a set of suitable E's and I's and a matching fibre bobbin you could easily make one with the correct guage insulated copper wire - again, a project only for experienced people.

For the benefit of people new to the hobby of vintage radio collection and restoration, all valve radios that plug into the mains contain a transformer that does two jobs. The first is to provide an extra-low voltage for the valve filaments and this is usually around the 6.3 volt mark. The second job is to provide a high-tension supply for the tuned circuit and amplifier and this is usually around 350 volts in an Australian-made radio. After the rectifier valve this is 350 volts DC. In my early days as a collector I accidentally gave myself a 'belt' when a finger strayed close to the field winding on the loudspeaker of the second radio I'd purchased for my collection.

To tell you that it hurts more than mains voltage is an understatement. I was lucky enough to live to learn from complacency and inexperience but unfortunately it does not always work that way. People have died from such shocks and the only way to prevent further deaths is to pay as much respect to a valve radio circuit as possible. Rest assured that I learned from my mistake VERY quickly and 18 years later I am still in business, so to say.

One unfortunate thing I notice is when some people sell old radios they state that the set doesn't work but ""should only require a new valve"" or ""should be easy to get going"".

None of the above are ever true. Often there is nothing wrong with the valves at all and it is the condensers, maybe a resistor or two or the power transformer that require replacement. It is a fact that whilst valves are considered consumables just as a light globe is, they often last far longer than the humble condenser and in some cases the other parts mentioned. The claims made by some people in relation to ease of repair should be taken with a grain of salt and a recently purchased receiver should never be fired up without being thoroughly checked by an experienced person.

For more details on this I recommend reading the two safety-related articles here. As for the issue relating to testing/tagging, I will endeavour to gather some information on this and post an article on it soon.

There are a number of electrical wholesalers who can obtain isolation transformers.
This place in Sydney is just one:
http://www.flanagan.com.au/isolation.htm
They are a must have to safely work on valve radios.
They are also now essential in testing RCD's when testing and tagging equipment to prevent down stream trips.

Good call.

When buying one of these it is just a matter of selecting the correct VA rating. Good to see they are Australian made too. We do have some industry left here.

I might add this website to the Services Directory when I have a moment.

AS/NZS 3000:2007, Wiring Rules, was issued on November 12, 2007 and will become mandatory in all Australian States & Territories during 2008. Maybe this will reduce variations between the states.

Hi, Should also metion
S/NZS 3760:2003 : In-service safety inspection and testing of electrical equipment
Abstract
Specifies the procedures and criteria for the in-service safety inspection and testing of electrical equipment which is designed for connection by a flexible cord. It also applies to cord extension sets, portable outlet devices, portable residual current devices and portable isolation transformers. Appendices include detailed test methods. It does not cover type approval tests for the design and construction of the equipment, nor does it include any procedural rules for the safe use of the equipment.

Hi, Should also metion
S/NZS 3760:2003 : In-service safety inspection and testing of electrical equipment
Abstract
Specifies the procedures and criteria for the in-service safety inspection and testing of electrical equipment which is designed for connection by a flexible cord. It also applies to cord extension sets, portable outlet devices, portable residual current devices and portable isolation transformers. Appendices include detailed test methods. It does not cover type approval tests for the design and construction of the equipment, nor does it include any procedural rules for the safe use of the equipment.

AS/NZS 3000 (SAA Wiring Rules) is only for hardwiring in buildings. It doesn't apply to flexible cords or appliances.