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Posted By Topic: Non compliant Hot water isolation Kits

Aug 08 2019 17:44

Can any one tell me the Regulation or wiring rule where the old metal sheaved flexible isolation kits with the bare earth are non compliant, these kits are just plain dangerous, but still seeing these type getting connected to new hot water cylinders

Aug 08 2019 18:01

Nothing wrong with metallic flexible conduit, even for new installations, if it's correctly installed.

But when replacing a HWC, as long as the existing cabling is correctly attached and hasn't been damaged, no need to replace it.

Aug 08 2019 20:30

They are quite often too short to connect into a new cylinder.

Aug 08 2019 21:51

The bigger problem is replacement cylinders are being reconnected by plumbers who don't know and don't care about electrical laws or safety. If the existing wiring is too short, the tin snips are used to cut a slot in the sheet metal cover. If the insulation is failing, just wrap some tape around it.
I've seen old houses which still have the original main earth onto metal pipe, and the original 1/.044 (1mm) twin no earth to the HWC. But the plumber who replaced the cylinder has broken the continuity of the metal piping by inserting a section of plastic. Then the new HWC is poorly connected to the old wiring. The new cylinder probably has a larger element.

Aug 08 2019 22:21

Not to mention the switch on the wall is often only 10amps and the new element is 12 amps.

Aug 08 2019 22:29

This house was OLD. Must have had an original 750 or 1000 watt element. Plumber replaced the cylinder with a nice new one prewired with 3kw. The 2core 1mm rubber cable feeding it turned to melted goo...

Aug 09 2019 08:58

Agree (most) plumbers shouldn't be doing the electrical connections (some have the appropriate PL). Come to that some so-called electricians do some horrible things too.
And yes there are other factors like length, CCC and switch ratings to consider.

None of which has anything to do with metal flexible conduit being inherently unsafe.

Related: I see some suppliers of HWC connection kits have changed to using isolating switches, in anticipation of 3000:2018 being cited.
Haven't seen a PCU with isolation switch yet.