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Posted By Topic: old house switch board upgrade

Feb 25 2019 22:40

Good evening, old house with all the cables are "ROMEX" or "Non-metallic sheath wire",ground or earth wire is bare copper, need to install new sub-circuit and upgrade the switch board to modern circuit breaker with RCD protection, just want to ask can I keep the original sub-circuit with their old cables? the old sockets and switches may change to new one as well. thanks

Feb 26 2019 10:59

As far as im aware, If the cables are visually ok and pass a insulation resistance test then it is ok to keep them.

I would be trying to upsell a rewire or even an AFDD

Feb 27 2019 01:54

"Romex" and "non-metallic sheath" are US terms? Are you in the US, or has someone imported US cable here?

I wouldn't touch it with a bargepole. This is in 'never complied and never will' territory.

Feb 27 2019 10:22

They use the terms GFI GFCI in the US not RCD. Could be a US sparky that has moved here and is still 50-50 with hi terminology.

Feb 27 2019 11:19

That looks like a PDL 60 single switched socket dating from the 1960s - 70s. Pic is too small to see whether the earth contacts have spread, but for well-used sockets they often are.

TPS with bare PEC was common in the 1960s.
ESR 113 says it can remain in service provided it still complies with original rules and isn't electrically unsafe.

Original rules included max 2 sockets on a final subcircuit with "coarse protection" (eg SERF). Upgrade to mcb allows more.

Sizes will be imperial, so use App I for checking overcurrent protection. Especially important since BTI may well have been added to the structure, triggering need for de-rating. The PECs are likely to be smaller than the live conductors; which makes Table 8.2 unsuitable for EFLI. But as long as the PEC resistance is OK, EFLI should be as well. Original requirement was 0.5 ohm universally, but now Table 8.2 allows more on low-rated circuits.

Ends of bare PECs should be sleeved green/yellow when any work is done on the connections. This will become mandatory when "3000" 2018 is cited by ESRs.

Feb 28 2019 05:22

Thanks AlecK, thanks everyone.

Every thing in AlecK's reply are correct, the cable is TPS with bare PEC, I just borrowed America terminology;
The cables still in reasonable good condition, plus a big house and not whole house renovation, kitchen only so I will keep the cables, upgrade switch board, change the old fittings;

The bare earth in switch board and end of earth with fittings connection will be sleeved green/yellow, quite a lot extra work.

Feb 28 2019 17:21

You only need to sleeve the earth at the fittings if you're doing work there. Otherwise they can stay as is.

I assume you're aware of the rules about who can do electrical work?