I have four 1950s radiograms all with the figure 8 power cords. I assume the power transformer ia acting as an isolation transformer. The chassis of the radio and turntable are not earthed.

For modern standards , do the chassis need to be earthed?

Get ready Arcadus for many detailed explanations but the answer is the metalwork should be earthed for SAFETY.
Yes.
Fred.

Life was cheap when these things were made... Fires were more common too....

The thing to remember is the insulating materials they had access to back then. Paper, wax, linseed oil, bitumen, rubber etc. All flammable. All deteriorate over the years, break down and carbonise.

Get the picture?

In addition to a mains safety earth I will normally add a thermal fuse to the transformer.

Modern standards for non-safety-earthed equipment require two independent layers of effective insulation of an approved type. Just about impossible to achieve or ensure in old gear...

I have a copy of the 1937 Trade Annual. It is surprising so see that there was actually specs for these, one was that the material was not able to support combustion and the insulation requirements are also listed. I think this one reason they were in the main, fairly robust.

I am not a fan of figure 8 mains wire, and I have seen rubber stuff falling to pieces on one that was taken out of service briefly, as it was forgetting words & music and started to hum. Like it had only one cap ever replaced prior to me getting at it.

Some of the transformer sets have shielded transformers, that type of transformer bleeds charge onto the chassis. Earth it & you get rid of it. It also in most cases gives the antenna a return path. Leave the earth wire longer so that if there is a serious tug on the cable causing breakage, its the last to fail.

Marc

First: Never try to earth a 'hot chassis', that is one without a mains transformer, as in such cases one side of the AC mains is usually connected to the chassis and if it happens to be the active side because of the way the plug is wired then you'll create a massive short circuit. In fact be VERY careful whenever working on a hot chassis, they can be lethal. All high voltages around valve radios can be lethal, but these sets are particularly dangerous. Power hot chassis sets via an isolation transformer for additional safety.

Note that these days the mains earth connection to the chassis is not permitted to be soldered. The earth wire has to be crimped onto a lug which is then bolted to the chassis with a star washer.

Here's the idea, except use our standard green/yellow earth wire:

https://www.caravansplus.com.au/detail-pages/help-files/240v-earth.jpg

Also, use a cable gland to secure the mains cable to the chassis. You can install them backwards (inside out) if space is an issue or for aesthetic purposes:

https://www.evatco.com.au/assets/full/12mmcablegland.png

Thanks everyone for the input, much appreciated.
I normally use the extension cords from the Reject Shop for replacements but they are white...
I guess brown cord would be appropiate for a proper restoration.

You can buy "Suicide" cables from various locations, including some of the purveyors of parts on this site. These have Brown cloth covers, but come with a molded plug.

A problem with cloth is its ability to creep back & cut. I will often use the more expensive shrink tube as a sleeve, where it passes through a gland. Be very careful, a heat gun and leave the tube a bit long to act as a strain reliever. It is often better to put the Gland inside out as it sticking out can result and assist in damage.

I was amused by and Electronics Mag when one of my restorations made it in and the use of the "Gland" was criticized (correspondence exchanged): Only to find, in pretty much the next edition a project with "Glands".

A trap not noted, & yet another example of "How the hell did this get into the country?". I have on various occasions found instruments & radios, often with two wire cables, where a cap of around 0.01 to 0.047μF can be found on the mains side. The Americans do this a lot.

Often this cap is from mains to a metal chassis, but in some cases, from mains to a metal cased instrument. The American NEMA 2 pin plug is reversible (straight pins). It in the case of a radio it is the return to ground for RF. The problem is that this cap/s can end up on Active. Often these are ordinary paper, or oil filled ones (bad news also) of dubious integrity. Any cap on the mains should be an approved mains type / Line cap. I have actually seen the can type oil filled ones exploded.

If I find (and have got) transformer apparatus like that that it will be rewired with a grounded cable. If you see one of those caps exposed to the mains and it needs to be there (hot chassis): It should be replaced with the approved type. I often use those in Vibrator power supplies on the vibrator side.

US clock radios use AC cord for FM antenna (with ceramic coupling cap), illegal in the Commonwealth I suspect.