Yeh! Wondering about that. Was the one that did not trip lights? Yes some old refrigerators did like tripping breakers. Brad may confirm if some of the modern circuit breakers incorporate earth leakage, never actually tried mine to see, albeit there is a stand alone one in this workshops supply.

Energy safe Vic was promoting Megger (tm) testing circuits at one point but with RCD's fitted that may be getting redundant. The purity of the water can influence conductivity. Deionised pure water is a non conductor & corrosive & used to cool some transmitter valves & by adding appropriate salts, it was used as a resistor in motor control (Alexanderson transmitter) and to test high power transmitters.

I think Ian maybe right , because the sparky mentioned that as a possibility.
GTC , no he tested my old fridge and said it's ok.
The all but one power point went out !!
Tripped the RCD switch

Pete: what I am having trouble understanding is how a faulty water heater could take out your power points as well. Heater and GPOs (power points) should be on separate circuits ... or is this an instant water heater plugged into a power point?

Note purity of the water marcc.
Rust in the water from the Taps ,hot water only

GTC, I don't know ,but the sparky said it's possible the water system is doing it !
Tonight there is no hot water.
The RCD has not tripped on the any RCD switches this time

Rusty hot water is a pretty good sign that the tank is falling apart. Another clue is green stains on basins courtesy of the amount of copper leeching from the tank's lining when it is on the way out.

The hot water heater should not be on the RCD circuit but obviously it is.

Heater elements in storage heaters like yours are a loop of tubing with a ceramic-insulated central heater element. Very similar to an oven heater element or some electric kettles.

When the element fails, an arc often develops which blows a hole in the side of the outer tube. Water gets in, leakage to ground happens.

Ok this chassis is a little out of my skillset. I have decided to send it to a tech I know very well and even if the tranny needs rewinding I will get it done properly. These old sets deserve to be preserved.

Robert I will look and see if I have a spare 2A5 I might but dont know.

Back when RCDs were first available in the early 1990s it was quite common just to fit a 100A RCD to replace the existing main switch. The law didn't require RCDs for each final subcircuit back then.

In fact, it was commonplace to include everything and optionally run a separate final subcircuit to the GPO feeding the fridge because on older fridges, condensate buildup on the door switch or interior light would trip the RCD and as luck sometimes had it, this usually happened when the householder was away and often came back to a fridge full of rotting dairy and meat.

If you got your switchboard replaced today, it would come with a combination RCD/MCB for each and every final subcircuit, no matter what the circuit fed.

Pete: a photo of your switchboard would be useful.

GTC,
Hi G , I will take a pic tomorrow.
I put off getting the sparky out till Monday, This morning I had hot water !! But it's not very hot.
That heater is had it , I looked at it and it was installed in 1982 lol..

The salts of Magnesium are notorious for chomping copper & there were some imported copper pipes that were vulnerable. The well water here (not currently being used) has a round 7gpl of solids. It will dezincify bronze and also likes brass. With it, if a brass tap starts leaking it is often a case of keeping the washer & throwing away the rest if one cannot restore the seat. Metal tanks also had an attrition rate.

New SS HW tank 2000 had killed two elements by 2012.

It is not used in automotive radiators and some are quite old Tractors is 70 but has an Aluminium Thermostat assy and an aluminium bung in the head as a sacrificial anode. I did in the 70's replace the Thermostat Assy but since I took over its maintenance its run 40% inhibitor & was still serviceable at the end of 2019. Next oldest radiator core 1982.

Agree with Brad on fuse boxes the originals were 1962 here (Distribution & 3 sheds and house.) any wiring mods in later life saw RCD's added. 2012 system was split in two with the studio originally off the house (by that time demolished) becoming the second meter box and used to build & supply the new house from a new underground line. House has a sub board inside. 2016 Major upgrade all supply put underground and fuse boxes (4) and the new distributor brought compliant to 2016. That now means the house & its studio are on their own as are the rest.

I have noted before that what can cause issues hitherto not known by many, is that whilst Neutral is tied to ground in most cases after an RCD it floats as an "entity''. So, where a neutral earth short previously often went unoticed, with an RCD it will be. In one case a 3HP grinder motor never used with an RCD tripped with an RCD. The jacketing (paper) of the cap had deteriorated & gone to ground. Replace jacket with stuff from motor rewinder; All good.

it was installed in 1982

Good grief! I'm lucky to get 8 years out of a Rheem. I've come home to a flooded rear of the house when I let one get too old. I was about to sell the house so put off the expenditure.

If your HWS was installed in 1982, it's done its job. You can rest assured that the new one will not last that long. I recommend Dux if the pipes will allow. A few things to consider though, you may be in an area that requires you to install a tank with a heat pump instead of an electric element. If so, these are a bit more expensive but they are cheaper to run. The heat comes from a refrigeration unit attached to the top of the tank. The downside with these is that they don't get connected to the off peak meter, just the standard tariff meter. Also, the water won't be as hot as before because in most cases the thermostat will be preset to 55°C instead of the old 75°C.

Most mains pressure HWSs are fitted with a sacrificial anode. If this isn't replaced, the water will eat the tank away where the spigots are welded to the tank once the anode is gone. Most plumping wholesalers play hard to get when someone goes in an asks for a replacement anode. It is a conspiracy set up jointly by all manufacturers so they can sell more tanks. Depending on water pH, hardness and mineral content you should get between 2 and 5 years out of an anode.

Gas heaters are worse. I got about 15 years out of mine despite two changes of anode. Had to source these online - have to be careful you don't get aluminium instead of magnesium.

It also failed at a spigot - the cold inlet at the bottom. Trouble with gas heaters is that they have a flue up the centre so that there is an annular water space and it is impossible for the anode to see all of the spigots. The pressure relief spigot is 180 degrees away from the inlet and outlet spigots.

Another problem is it is impossible to adequately flush out the heater to get rid of sediment as there is no spigot at the bottom of the tank where the concave base is welded on. The cold water inlet is too high up to get the sediment that settles at the narrow gap at the weld. I poked a length of hose down through the anode spigot at the top and got some of it but am sure not all. While this heater failed at the cold spigot I have seen electric heaters fail at the concave base seam weld.