Tps wire size identification

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mb82

223 posts

Master Geek

#304322 23-Apr-2023 23:02

My house is 1990. Wire for power points is obviously thicker than light switches. It is 3 wire red black and green. 3 strands of copper per wire colour I measured each strand of copper to be about 0.95mm thick. Is this 2 5mm tps cable? Can't see enough of it to read if anything is written on it and crawling in attic trying to see it was not fun

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#3067461 23-Apr-2023 23:15

One strand is typically 1.0mm, three strands is typically 1.5mm, and seven strands is 2.5mm. Take those numbers with a grain of salt though, as the only real way to tell what you've got is to read the specs on the outer insulation.

John19612

68 posts

Master Geek

#3067475 24-Apr-2023 08:19

Accurately measure the diameter of one strand of the conductor.

Calculate the cross sectional area of that strand using the formula: A=(pi*diameter^2)/4

Multiply the answer by the number of strands in the conductor.

If it is only a single strand then it is 1mm^2.

3 strands @ 0.95mm dia is 2.13mm^2. So, yes, it is 2.5mm^2 cable.

Daynger

435 posts

Ultimate Geek

#3067921 25-Apr-2023 18:59

What did you measure the cable cores with?

As above, more likely to be a 1.5mm cable unless its some oddball or very old one.

What size circuit breaker is protecting the cable?

SATTV

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#3068023 26-Apr-2023 07:47

Our house is mod 60's and has 2.0mm TPS on some of the power circuits, when I got an electrician to change the board he had to shoot out and get 16A breakers instead of the usual 20A breakers.

John

I know enough to be dangerous

Daynger

435 posts

Ultimate Geek

#3068611 28-Apr-2023 00:17

SATTV:

Our house is mod 60's and has 2.0mm TPS on some of the power circuits, when I got an electrician to change the board he had to shoot out and get 16A breakers instead of the usual 20A breakers.

John

That will be an old imperial sized cable, 3/036 or something.

https://www.diynot.com/wiki/Electrics:Old-Imperial-cable-sizes

mb82

223 posts

Master Geek

#3069155 29-Apr-2023 09:59

Daynger:
What did you measure the cable cores with?

As above, more likely to be a 1.5mm cable unless its some oddball or very old one.

What size circuit breaker is protecting the cable?

Measures the cable with a cheap vernier.
Breaker size interesting 3 circuits are 15amp wire ceramic housing, kitchen and laundry have been changed to 20amp breakers.

Could not see wire size on cable just says:
1368
1989
International industries ltd auckland nz
Elec cable 600/1000v

larknz

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#3069221 29-Apr-2023 15:10

SATTV:
Our house is mod 60's and has 2.0mm TPS on some of the power circuits, when I got an electrician to change the board he had to shoot out and get 16A breakers instead of the usual 20A breakers.

John

If the house is mid 60s the wiring will definitely be imperial and probably 3/.036, which is basically equivalent to 1.5mm.

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larknz

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#3069222 29-Apr-2023 15:15

mb82: My house is 1990. Wire for power points is obviously thicker than light switches. It is 3 wire red black and green. 3 strands of copper per wire colour I measured each strand of copper to be about 0.95mm thick. Is this 2 5mm tps cable? Can't see enough of it to read if anything is written on it and crawling in attic trying to see it was not fun

3 strands will be 1.5mm, 2.5mm is 7 strands. Although in the early days of metric there was a single strand 2.5mm.
In the earlier days the cable size was not printed on the outer sheath.

Daynger

435 posts

Ultimate Geek

#3069333 29-Apr-2023 18:56

mb82:
Measures the cable with a cheap vernier.
Breaker size interesting 3 circuits are 15amp wire ceramic housing, kitchen and laundry have been changed to 20amp breakers.

Could not see wire size on cable just says:
1368
1989
International industries ltd auckland nz
Elec cable 600/1000v

90s house with ceramic fuses?

I thought it was circuit breakers by then, but its a little before my time.

Are you sure its not an old house that had a remodel in the 90s?

mb82

223 posts

Master Geek

#3069495 30-Apr-2023 13:04

Daynger:
mb82:
Measures the cable with a cheap vernier.
Breaker size interesting 3 circuits are 15amp wire ceramic housing, kitchen and laundry have been changed to 20amp breakers.

Could not see wire size on cable just says:
1368
1989
International industries ltd auckland nz
Elec cable 600/1000v

90s house with ceramic fuses?

I thought it was circuit breakers by then, but its a little before my time.

Are you sure its not an old house that had a remodel in the 90s?

Was built 89/90

mb82

223 posts

Master Geek

#3115382 13-Aug-2023 18:45

I have confirmed the cable size is 3/.036 imperial which is 1.970mm2

Anyone know the rules about swapping from single to double outlets?

larknz

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#3115390 13-Aug-2023 19:20

If it has rewireable fuses you were only allowed 2 sockets per circuit, although many have replaced single sockets with doubles.

mb82

223 posts

Master Geek

#3115401 13-Aug-2023 20:59

larknz: If it has rewireable fuses you were only allowed 2 sockets per circuit, although many have replaced single sockets with doubles.

Yes there are only two single outlets per circuit on 15amp rewireable fuses.

Odd considering with 2.5mm you can have 12 double outlets per circuit.

Basically wanting to know if I can change them to doubles and still have it be up to standard. Would an electrician refuse to change them

neb

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#3115402 13-Aug-2023 21:03

Friend of mine mentioned in passing today that her house, built as cheaply as possible, used one-size-smaller-than-required cable (I'm guessing 1mm lighting instead of 2.5mm standard) for at least some of the power points. She's running heaters off that... I asked if she could get to any cable run and see how warm it got, but it's all buried inside walls.

Bung

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#3115424 13-Aug-2023 23:46

neb: Friend of mine mentioned in passing today that her house, built as cheaply as possible, used one-size-smaller-than-required cable (I'm guessing 1mm lighting instead of 2.5mm standard) for at least some of the power points. She's running heaters off that... I asked if she could get to any cable run and see how warm it got, but it's all buried inside walls.

One size smaller would be 1.5mm which I think was used for outlets in past (smaller houses, fewer outlets per circuit).

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