lighting adapter to 3 pin plug

[AndyPRK]

I’m too young. But I thought 5A and 15A sockets were fitted/present at the same timeframe.

Therefore a lamp would have a 5A plug

 

[SUNRAY]

Dunno.

A size which was OK with a 15A fuse for protection?

probably a bit of 19/0.0076" or about 0.5mm²

oops - my apologies, for some reason (I'll try blaming the heat) I thought the ebee/mikehammer sub-topic was 30/32A circuits.

 

[SUNRAY]

I’m too young. But I thought 5A and 15A sockets were fitted/present at the same timeframe.

They were

Therefore a lamp would have a 5A plug

even if the house had no 5A sockets?

 

[ebee]

You might limit the expected normal maximum consumption by number of sockets or by area served or even by both.
How ideal is that? or not?

Example - limit area served to 100 square yards then a few years later redifine the limit to 100 square metres, the difference is nearly plus 20% (around 19.6%), what would have happened if we had picked an area of double that size or half of that size?

PS - If we revert back then the difference is nearly minus 16% (around 16.4%)

 

[mikehammer69]

It matters a great deal - before we had fused plugs circuits were 15A radials with unfused 15A plugs.

The change to 30A ring finals necessitated changing to fused plugs.




With an unfused plug it also protects the power cord.

What size would such cords have to be if their only protection was a 32A MCB or a 30A semi enclosed?

No - you can't have 15A unfused plugs with 30/32A circuits.

Overload isn't a big issue with appliance cords is it

Isn't the cord mostly protected by the load being sized to match the cord ?

 

[securespark]

so what size flex was supplied on table lights in the days of BS546 15A?

The imperial equivalent of 0.5, or 0.75, I would think. The flex would possibly be twisted figure of 8, flat twin or round twin or three core depending on the era and the lamp.

Houses wired with round pin sockets usually had a mix of 15A and 5A, but IME, I saw a lot more 2A in place of the 5s.

I generally saw table lamps plugged into the lighting sockets, not the 15A power sockets.

 

[securespark]

I know radials use more cable, but I prefer them to ring finals.

They're easier to test, inspect and fault-find. And they can't be DIY-butchered quite so easily.

 

[mikehammer69]

If i’m recalling correctly appliance cords are now fused at 3 or 13 amp

Over 700w ? appliance is fused at 13amp

Some 13 amp appliance cords are not overload protected ie ; 0.75 and 1 mm cords fused at 13 amp

 

[davelx]

They were

even if the house had no 5A sockets?

And not a 5A fuse in sight.

 

[SUNRAY]

View attachment 419851
And not a 5A fuse in sight.

Indeed and not only that, I've also seen 30A adapters with % & 15A unfused sockets


EDIT: That should be 30A adapters with 5 & 15A

 

[ebee]

I know radials use more cable, but I prefer them to ring finals.

They're easier to test

Sometimes but not always.
I`ve seen quite a few radials resembling a tree, in fact we did do a bit about "trees" as circuits at night school a few years back.
Not every radial has a simple beginning and a simple end, notevery radial has no branches.
You could end up with 10 ends and only 1 to 20 total on the whole circuit.

I must admit I like to think of a radial as a simple begining to end circuit but I do bear in mind what I might come up against in reality, much in the same way that I have found a ring or two to be a radial or two with two ends (a 302A MCB at each end of a "ring" is not good news and has often been missed. Much in the same way a radial or three might be connected to one consumer unit "Switchfuse" for N and a different consumer unit for L) .

It makes life interesting

 

[AndyPRK]

I saw a lot more 2A in place of the 5s.

Good point. I do have a couple of 2A where I would have expected them to be 5A.

 

[FrodoOne]

Much discussion here concerning the so called mismatching of the Load (device) to the Supply (availability).

Circuit breakers (and CU fuses) are there to protect the internal wiring of a building from overload,
which may otherwise result in the overheating of in-wall conductors and possible fire - Unseen for a short time.

If a normally "low powered" device is plugged into a MUCH higher supply outlet than the device is normally intended to draw,
nothing untoward will happen - unless the "low powered" device develops a fault,
which causes it to draw significantly more than its rated load.

For such a device to draw significantly more than its rated load, it is probable (virtually certain)
that a short circuit has occurred within the device and it (or part of it) is (or is being) destroyed.

Since the device is now "beyond redemption",
what is necessary is to stop the flow of electricity,
to prevent damage to the internal wiring of the building
and to the external wiring within the premises of the building - if any.

While overheating it,
It is extremely unlikely that
a short circuit causing destruction of a "device"
would "pull" sufficient current (in the short time involved),
via any "Low Capacity" cord which may connect it.
sufficiently to cause other damage to the premises
without operating a (say) 32 A Circuit Breaker.

(In other words, you won't see the cord go up in flames if any Power Supply or Lamp develops a Short-Circuit.
Consider also a direct plug-in Power Supply)

My reasons for pointing this out is to show the "logic" which exists behind the design of "Socket Outlets" in Australia/New Zealand.
(Please view https://commons.wikimedia.org/wiki/...cket_styles_for_different_current_ratings.jpg )

Standard single phase 230 V domestic socket outlets in Australia and New Zealand are rated at 10 A - as are Lighting Circuits.
(The 10 A [and 15 A] Socket-Outlets "exist" on circuits which are rated at 20 A,
much as UK 13 A Socket Outlets may exist on 20 A or 32 A circuits.)

However, for heavier duty applications there are several variants having current ratings of up to 32 A:

• The 15 A outlet has a wider earth pin than the 10 A outlet.
• The 20 A outlet has a wider earth pin and wider Line and Neutral pins.
• The 25 A outlet has an inverted L-shaped earth pin and wider Line and Neutral pins.
• The 32 A outlet has a sideways U-shaped earth pin and wider Line and Neutral pins.

From this it may be seen that any "plug" can be inserted into a socket outlet of the same or higher rating but cannot be inserted into a socket outlet of lower rating.

Hence, a 10 A plug will fit into all of the five types of socket outlets, a 15 A plug will fit into all except a 10 A (and so on) while a 32 A plug will fit only into a 32 A socket outlet.

In general, only 10 A and 15 A socket outlets are likely to be encountered in domestic or commercial installations.
Higher rated socket outlets, used for the connection of electric ovens in domestic kitchens, are usually hidden behind ovens and never seen by the Customer.

 

[ebee]

Much discussion here concerning the so called mismatching of the Load (device) to the Supply (availability).

Circuit breakers (and CU fuses) are there to protect the internal wiring of a building from overload,
which may otherwise result in the overheating of in-wall conductors and possible fire - Unseen for a short time.

If a normally "low powered" device is plugged into a MUCH higher supply outlet than the device is normally intended to draw,
nothing untoward will happen - unless the "low powered" device develops a fault,
which causes it to draw significantly more than its rated load.

For such a device to draw significantly more than its rated load, it is probable (virtually certain)
that a short circuit has occurred within the device and it (or part of it) is (or is being) destroyed.

Since the device is now "beyond redemption",
what is necessary is to stop the flow of electricity,
to prevent damage to the internal wiring of the building
and to the external wiring within the premises of the building - if any.

While overheating it,
It is extremely unlikely that
a short circuit causing destruction of a "device"
would "pull" sufficient current (in the short time involved),
via any "Low Capacity" cord which may connect it.
sufficiently to cause other damage to the premises
without operating a (say) 32 A Circuit Breaker.

(In other words, you won't see the cord go up in flames if any Power Supply or Lamp develops a Short-Circuit.
Consider also a direct plug-in Power Supply)

My reasons for pointing this out is to show the "logic" which exists behind the design of "Socket Outlets" in Australia/New Zealand.
(Please view https://commons.wikimedia.org/wiki/...cket_styles_for_different_current_ratings.jpg )

Standard single phase 230 V domestic socket outlets in Australia and New Zealand are rated at 10 A - as are Lighting Circuits.
(The 10 A [and 15 A] Socket-Outlets "exist" on circuits which are rated at 20 A,
much as UK 13 A Socket Outlets may exist on 20 A or 32 A circuits.)

However, for heavier duty applications there are several variants having current ratings of up to 32 A:

• The 15 A outlet has a wider earth pin than the 10 A outlet.
• The 20 A outlet has a wider earth pin and wider Line and Neutral pins.
• The 25 A outlet has an inverted L-shaped earth pin and wider Line and Neutral pins.
• The 32 A outlet has a sideways U-shaped earth pin and wider Line and Neutral pins.

From this it may be seen that any "plug" can be inserted into a socket outlet of the same or higher rating but cannot be inserted into a socket outlet of lower rating.

Hence, a 10 A plug will fit into all of the five types of socket outlets, a 15 A plug will fit into all except a 10 A (and so on) while a 32 A plug will fit only into a 32 A socket outlet.

In general, only 10 A and 15 A socket outlets are likely to be encountered in domestic or commercial installations.
Higher rated socket outlets, used for the connection of electric ovens in domestic kitchens, are usually hidden behind ovens and never seen by the Customer.

Ive seen one or two electrical installations on the East Cost of OZ, one thing I noticed was they seemed to favour consumer units on the outside of a property (all be it in a "cupboard" ), is this the normal standard?

Reason I ask is 1/ It seems that any miscreant might decide to walk into the garden and decide to mischievously thro the breaker or main switch etc and 2/ OK if in good weather (as it usually is (I think) but I do know that they can sometimes get some terrific downpours/hail too which means a person is not so comfortable going outside to reset/recheck in the case of a trip etc.
Must make inspect and test (and faultfinding) more than a bit difficult at times too.

 

[mikehammer69]

I was about to post a similar query to FrodoOnes post

If i'm not mistaken it would be very unusual for a appliance cord to become overloaded

As i posted already , afaik some appliance cords are not protected against overload . Small cords fused at 13A