10a or 20a for light switches?

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MrLeggo

23 posts

Geek

#310660 10-Nov-2023 12:10

What amperage should a light switch be, 10a or 20a?

I'm replacing some sockets and light switches with new ones. The PDL Iconic plugs are 10a, but the PDL Iconic light switches only seem to come in 20a!
https://lightingelectricalsupplies.co.nz/index.php?route=product/product&product_id=50

My understanding is that a higher rating (20a) is OK to do.

Any thoughts?

MattEast

277 posts

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#3157988 10-Nov-2023 12:14

Yes, the 20 Amp switches will work just fine...you might pay a little more for them, but if that's the only rating they come in...your choice is limited.

Matt East

Rikkitic

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#3158007 10-Nov-2023 13:12

Amps are a measure of current flow. As long as the switch meets or exceeds the current rating, you are fine. It doesn't hurt anything. It just means you have more than you really need. A problem only occurs in the other direction. If the current flow exceeds the rating, that can cause overheating and burnout and all kinds of grief.

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raytaylor

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#3158263 11-Nov-2023 13:07

If your lighting circuit controlled by the switch is less than 1.5kw then you will be fine with either option.

To make 1.5kw would require 15 old 100w halogen bulbs, or 40 typical LED bulbs so i doubt you will have an issue.

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BadCo

109 posts

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#3158355 11-Nov-2023 16:11

raytaylor:
If your lighting circuit controlled by the switch is less than 1.5kw then you will be fine with either option.

To make 1.5kw would require 15 old 100w halogen bulbs, or 40 typical LED bulbs so i doubt you will have an issue.

This doesn't make sense.

The switch mech rating should be equal to or greater then the protective device in the switchboard. For lighting that is usually 16a, so the 20a switch mech will be fine.

Switch mech usually are rated for 20a so you can use them as isolators for appliances etc. Except for some brands, looking at you HPM excel life...

SomeoneSomewhere

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#3158368 11-Nov-2023 17:05

Side note, because I see this bandied about frequently:

LIGHT SWITCHES ARE NOT SUITABLE AS A 'DEVICE FOR ISOLATION' - See 2.3.2.2.

In general they will be a functional switch that provides a convenient way to remove power if the controls fail or you want the device off.

Most things have no requirement for an actual isolator to be located nearby. Even for cooktops, it only needs to be a functional switch. For most other things, it is compliant to point at the MCB in the switchboard and call that the isolator.

For things that do require a local isolator, such as heat pumps and many motors, it must be lockable (or removable links/fuses), marked with on/off positions, unable to falsely indicate contact positions (e.g. if the contacts are welded, you physically can't turn the handle to off), and have a suitable contact gap.

BadCo

109 posts

Master Geek

#3158371 11-Nov-2023 17:20

SomeoneSomewhere:
Side note, because I see this bandied about frequently:

LIGHT SWITCHES ARE NOT SUITABLE AS A 'DEVICE FOR ISOLATION' - See 2.3.2.2.

In general they will be a functional switch that provides a convenient way to remove power if the controls fail or you want the device off.

Most things have no requirement for an actual isolator to be located nearby. Even for cooktops, it only needs to be a functional switch. For most other things, it is compliant to point at the MCB in the switchboard and call that the isolator.

For things that do require a local isolator, such as heat pumps and many motors, it must be lockable (or removable links/fuses), marked with on/off positions, unable to falsely indicate contact positions (e.g. if the contacts are welded, you physically can't turn the handle to off), and have a suitable contact gap.

n

No one is talking about a 'device for isolation', I'm referring to the switches above your bench that turn off your oven etc.
What you refer to as a 'functional switch' but I guess in slang terms is referred to as an isolator.

Bung

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#3158381 11-Nov-2023 18:37

If you stop thinking of the switch as an isolator you'll be less likely to get caught hanging from a light fitting when some random walks into the room and flicks the light on out of habit.

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SomeoneSomewhere

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#3158408 11-Nov-2023 20:45

Yup. Or when you go to install something that does legally need a local isolator (like a hot water cylinder if we ever adopt the 2018 rules), but doesn't need the whole IP-rated shebang used on e.g. heat pumps.

It's also worth thinking about whether it's necessary at install time. Less so in residential - if your rangehood gets stuck on, it's nice to be able to switch it off without cutting a whole power or lighting circuit, or opening it up to remove the plug.

But if you're installing an 'isolator' for a group of lights, which is on a motion control and a remote lighting controller? What's the point of installing a random unmarked light switch up high in a corridor somewhere? It'll never get used, with the possible exception of someone using it to do maintenance they shouldn't. You're just wasting a switch and some cable.