Question for Electrician

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mrscat, Jul 27, 10:12am
My old 1920 bungalow still has its old wiring. After a visit for an electrician to replace lights, he said wiring ok for replacement but not for other work. My question is what work would be required to install heat pump. thank you

peanuts37, Jul 27, 11:15am
Heat pump would require being wired from meter board so new wire run and possibly new meter board as old wiring may be to old.

trade4us2, Jul 27, 3:02pm
My wiring and meter board must have been installed at the beginning of electric power in NZ. The inspector said it was horrible! The house used to have gas lights.
The wire was really cheap at Mitre10 when I looked last, like about 5 times cheaper than electricians charge. There is some kind of scam going with the cost of wire.
I would recommend that you replace all the wiring and put in insulation as well. What's the plumbing like? I had all mine replaced.

tweake, Jul 27, 3:56pm
i have heard that some like mitre10/bunnings are able to buy it in large quantities and are able to supply it much cheaper. local sparky started buying from bunnings instead of their usual wholesaler.

bill1451, Jul 27, 6:06pm
cable made in China
and not certified I,m picking, its cheap because there isnt as much insulation
as NZ made product, support your local industry buy NZ made. Under a bit of load it will break down and burn your house down, rewirable fuses wont work.

johotech, Jul 27, 6:17pm
Your "local sparky" can't have a very good account at the wholesaler. Bunnings normal cable prices are around 150-200% of what an electrician should pay for cable, when buying a full roll.

Electricians could charge the same as Bunnings on a large job, but for a small job, you'll be paying a higher price for shorter lengths.

But does it really make much difference? You want 15m of cable for a heatpump, you can pay $3-4/m at the hardware shop, or buy a whole roll for $240 - or pay the electrician $3.50 per meter or whatever for exactly what you need.

Aren't we supposed to be supporting local businesses like electricians?

tweake, Jul 27, 6:26pm
i don't think its china made products and its all the products.
i suspect they are getting screwed over by the wholesaler.

seeing that in other products where the wholesalers are inflating prices to the point you can buy the top end brands for what they want for the cheaper brands.

gyrogearloose, Jul 27, 6:36pm
The last time I bought wire at Mitre10 I was staggered at the cost. Perhaps you were looking at the cheapest wire which might not be suitable for the run length, bundled wires, enclosed spaces, and amperage required for a heat pump.

If my house had original wiring from the 1920's I'd rely on the electrician to supply suitable wire, and I'd get every bit of cabling replaced and expect to fixup major cuts in the wallboards afterwards. You can't expect the house to have easy conduits for new wire. And I'd want a compliance certificate from the electrician.

And heatpumps, I'd be thinking about the roof, underfloor and wall insulation too. It's a major cost, but an asset that enhances the value of the house.

trade4us2, Jul 31, 4:20pm
The wire was made by General Cable NZ and was dated a few weeks before I bought it. It cost about $2.90 per metre.
I see that Mitre10 currently have a different brand for $2.96/metre.
https://www.mitre10.co.nz/shop/non-branded-flat-twin-earth-tps-cable-reel-2-5-x-100-white/p/290271
Complies to relevant New Zealand standards AS/NZS5000.2:2006.

androth2, Jul 31, 8:51pm
A 1920 house would have steel conduit with fabric covered wire inside it

tweake, Jul 31, 9:06pm
maybe not. could have been changed to that rubber type they brought out at one point.

buynsellmodels, Jul 31, 10:25pm
Had a job today, at some point in the last couple of decades a tradesman added a lighting TPS cable from a basement existing trs 2 core lighting circuit for a sensor feeding two metal fittings.
Twisted the neutral and earth together in the thru plate/live plate batten holder to facilitate bonding the metal lights. with no isolating switch. nice job that bloke.

hulloitsme, Aug 2, 12:14am
I have a 2 core cable running via a wall switch, to a metal pendant lamp. I got up into the roof cavity to check it and the earth wire from the lamp isn't connected at all. Should the lamp earth be twisted with the neutral for a connection?

hulloitsme, Aug 2, 8:46am
Haha! The answer is "no way!"

mrfxit, Aug 2, 9:14am
All wall sockets should be earthed in NZ
All lamps made of metal should be earthed
If the lamp has a plastic case, then no earthed is required in most cases.

Pretty sure that items that mention "double earthed" are simply running an earth wire for internal parts & the outer case is plastic

captaingraham, Aug 2, 9:39am
Maybe not. Could be vir cable enclosed in wood casing.

captaingraham, Aug 2, 9:46am
-------- the term is double insulated and no earth is required. The fitting/appliance/tool would be labelled with a square within a square. However, todays wiring rules require an earth at all lighting points for new installations, even if it is not used.

andrew1954, Aug 2, 11:48am
Any sparkie putting plenty of business through his wholesaler will be getting drum of the commonly used sized cable at little to no mark up if not at cost or below. cable is often used as a “loss leader” . get the sparkie in the door to buy other stuff with a good mark up on. the pricing of cable is a “black art” . the sparkie may buy it cheap today from the wholesaler, but the wholesaler craws some of that back by the rebate etc the cable company pay at the end of the year!

vivac, Aug 2, 2:30pm
Close but not quite.
Wall sockets, yes, all need to be earthed.
Lighting there is a height component to it too, as in metal lights over a certain height do not need to be bonded, its been a while since i have needed to refer to that but i think it is 2.8m or something.
Double insulated is the term you are looking for too, quite common now for power tools.

sandymrph, Aug 2, 7:35pm
Let's get back to what the OP asked shall we ? My take - It's an 1920 bungalow with no categorisation of how old the actual wiring is.(If it's still got actual wiring from 1920 then they've got a heap of problems . or should I say. that's the start of their major problem. LOL) They have had an electrician in to replace some light fittings (not actually said definitively but inferred- from "After a visit for an electrician to replace lights" ) then "he said wiring ok for replacement of lights (the light fittings , replaced (?)), but not for other work". - I presume the electrician is alluding to. you need some serious upgrade (modernisation) of the wiring in your home.

ryanm2, Aug 2, 8:17pm
That’s certainly not the case now. What’s the difference between getting a shock at 2.4m or 3m? You full off a bigger ladder at 3m. I’ve always heard old sparkies discuss earthing requirements for light fittings above ‘x’ metres but not once could any ever point to any actual regulation for it not to be a requirement above a certain height.

johotech, Aug 2, 10:31pm
Have a look in the book for the definition of "earthed situation", and 5.4.1.1.
But it no longer applies for indoor light fittings. 5.4.4

vivac, Aug 3, 2:42pm
I have always thought the same, shock at height just means falling off a ladder, common sense doesnt always make the rules.

captaingraham, Aug 3, 4:52pm
In the good old days (late 1950's, early 1960's) there was no requirement to earth metal light fittings UNLESS they were within reaching distance of earthed metal, (stainless steel bench top, taps etc) so if fitting was in a kitchen, bathroom, laundry it would require earthing. No height restriction, metal wall brackets in living room or lounge at 1.8m were quite common. As I recall, the 1976 regulations changed the rules and the wording was "any metal liable to become alive must be earthed" Houses were wired with twin 1/044 cable(1mm today), 3 core cable hardly ever used.

mrfxit, Aug 4, 12:05pm
Yep "Double insulated" is pretty dang easy when the entire tool body is plastic