Old Valve Radios and the Queensland Electrical Safety ACT

When your old valve radio is being restored, the following work should be done by the holder of an electrical contractor's licence.

NORMAL 240V AC SETS

1 - Replace the power cord with a new three conductor cord, complete with a moulded plug - old bakelite plugs may no longer be used

2 - Replace the rubber grommet where the power cord feeds through the chassis

3 - Anchor the cord to the chassis with a clamp that will prevent force applied to the cord being transferred to the cable terminations.

4 - Terminate the earth wire with an approved crimp lug, and attach this lug to the chassis with a screw, nut and lock washer

5 - Where possible, cover the exposed 240 volt terminations with adequate insulating material

6 - With the active and neutral conductors on the plug connected together and the radio ON/OFF switch turned on (if applicable), use a calibrated 500 volt megger to measure the insulation resistance between the Active & Neutral plug connections and the chassis of the radio. The insulation resistance must be greater than 1 megohm

7 - With a calibrated 500 volt megger set to low ohms range, measure the resistance between the plug earth pin and the chassis of the radio. The measured resistance must be less than 1 ohm.

AC / DC SETS

If your set is an AC/DC set; ie, it does not have a power transformer and will operate from 200 to 240 volts AC or DC

(a) Only a two conductor cord is to be used, with the neutral side of the power input connected to either chassis or common, depending on the circuitry of the particular AC/DC set.

(b) The resistance as measured between active and chassis will vary widely, and again depends on the circuitry used.

(c) The chassis of the set should be completely enclosed so that it is not possible for the user to come into contact with any exposed metal components

(d) It is suggested that a warning sign, similar to the one below, be placed on the back of the AC.DC set.



INFORMATION ON THE WEB

The Act, all 152 pages of it, and a very useful abbreviated "Electrical Safety Act - The Guide", can be downloaded from the following web site. The file containing the Act is 869Kb in size, and the guide file is 100Kb.

Another practical document for electrical workers is the "Code of Practice for Electrical Work" at 484Kb.

All files are in the Adobe Acrobat PDF (Portable Document File) format, so you will need the freely available Acrobat reader from Adobe to open the files.

http://www.eso.qld.gov.au/legislation/index.htm