Microwave ovens and isolated outlets

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MikeB4

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#201845 6-Sep-2016 15:27

We are currently embarking on renovating our kitchen and in the process of getting sub trade quotes. The kitchen company we are using has said we need to get an isolated power supply for our microwave oven.

We are going to use our existing microwave as it is only few months old. This microwave is currently plugged into a standard wall outlet. It is going to be inset into a cabinet in the new kitchen.

Is this correct that the microwave now has to use an isolated outlet?

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Networkn
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#1624676 6-Sep-2016 15:52

Never heard of such things, esp given 99% of the microwaves in NZ wouldn't be on their own one.

antoniosk

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#1624677 6-Sep-2016 15:54

We have the same thing - microwave on the shelf. No isolation.

For every direct wired appliance - ovens, hob, hood and fridge (which is for convenience) - they are on an isolation switch

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trig42

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#1624678 6-Sep-2016 15:56

I'm not an electrician, but I can't see the logic in it. (If by 'Isolated Power Supply' they/you mean seperate circuit with it's own breaker at the switchboard).

Are you sure the kitchen people don't just mean it needs it's own wall socket? It may need a switch outside of the cabinet so you can isolate the power without reaching behind the MWO.

A MWO only uses 1000W max. A Kettle or Toaster would use the same, if not more. They don't need their own circuits.

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#1624681 6-Sep-2016 16:00

How modern is your house wiring, Mike? How much current does the microwave require? What else is fed from the circuit you want to use? I think there has to be more to it. If this is a requirement in New Zealand, which I very much doubt, there are an awful lot of microwave users in violation.

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Dynamic

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#1624682 6-Sep-2016 16:01

I wonder if they mean having an externally accessible switch like your master switch for an oven.

A microwave that fits snugly in a new set of kitchen cabinets will be plugged into a socket that can't be reached in an emergency (i.e. microwave emitting smoke). A separate switch on the wall which will 'isolate' (remote power from) the power socket that microwave is plugged into might be helpful in that situation.

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tchart

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#1624691 6-Sep-2016 16:24

Dynamic:

I wonder if they mean having an externally accessible switch like your master switch for an oven.

A microwave that fits snugly in a new set of kitchen cabinets will be plugged into a socket that can't be reached in an emergency (i.e. microwave emitting smoke). A separate switch on the wall which will 'isolate' (remote power from) the power socket that microwave is plugged into might be helpful in that situation.

We recently built (~6 months ago). Microwave has a dedicated socket. There is no separate switch for this socket - its just a normal socket. AFAIK its not on its own circuit on the circuit board.

Bung

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#1624692 6-Sep-2016 16:25

Our Panasonic microwave came with a recommendation to be on a separate 10A circuit to avoid tripping circuit breakers ( but few circuits would be limited to 10A). The label says 4.5A normal/7.5A initial current.

Isolation switch has a special meaning, most outlets may have a functional switch with the circuit breaker being the isolation switch.

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kingjj

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#1624693 6-Sep-2016 16:32

Brings back memories of flatting days when the microwave was on the same circuit as the kitchen light... you couldn't use both at the same time or it would trip....

We had our kitchen rewired last year and the microwave is on the same circuit as the fridge and dishwasher. No separate switch or anything.

mdooher

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#1624696 6-Sep-2016 16:37

They are probably recommending you be able to reach the switch with the microwave in place, not a bad idea, I might even say a good idea, same reason you don't put the dishwasher plug behind it.....however not legally required. Only the hob or a free standing range require such a switch.

also if the food in your microwave catches fire, or you left the tin foil on, just turn it off on the front and wait.

If you are getting a new plug put in they might mean you need an RCD fitted to that circuit

Matthew

gregmcc

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#1624700 6-Sep-2016 16:46

short and simple no, but I think they mean something else.

As the m'wave is in it's own little spot in the kitchen joinery the power point for it will be behind the m'wave, ideally you will need a separate "isolation" switch somewhere nearby that is easily accessible, similar to what is usually done with a dish washer.

....Yes I am an Electrician.

gregmcc

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#1624704 6-Sep-2016 16:50

mdooher:

They are probably recommending you be able to reach the switch with the microwave in place, not a bad idea, I might even say a good idea, same reason you don't put the dishwasher plug behind it.....however not legally required. Only the hob or a free standing range require such a switch.

also if the food in your microwave catches fire, or you left the tin foil on, just turn it off on the front and wait.

If you are getting a new plug put in they might mean you need an RCD fitted to that circuit

Isolation switches are only mandatory on socket outlets above 32Amp, 32A or below common sense should kick in - in the event of something going wrong how easily can you unplug the device, if you can't then it's time for an accessible switch somewhere.

MikeB4

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#1624706 6-Sep-2016 16:53

The wall plug will be easy to reach in an emergency

neb

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#1624780 6-Sep-2016 20:05

Dynamic:
A microwave that fits snugly in a new set of kitchen cabinets will be plugged into a socket that can't be reached in an emergency (i.e. microwave emitting smoke). A separate switch on the wall which will 'isolate' (remote power from) the power socket that microwave is plugged into might be helpful in that situation.

That would be one possible explanation, but then it'd also apply to almost every other appliance in the house: fridge, TV (in a cabinet), stereo/AV/DVD player (cabinet), dishwasher, washing machine, etc. Just thinking of my house and those of friends/neighbours, the only thing that has an accessible switch is usually the washing machine, and even then it's often above/beside the machine that's hypothetically on fire. In any case in the event of an electrical fire the first thing I'd do is flip the main house circuit breaker ("Shut them all down. Hurry! Oh, no"). Then figure out which circuit it was on after you've dealt with the fire.

solutionz

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#1624800 6-Sep-2016 20:48

Having just taken a product though standards testing I can tell you that "Household and similar electrical appliances" are required to have an accessible means of disconnection ("isolation") for safety being either:

A) Approved appliance mains inlet switch (microwaves don't usually have these).

B) Physical disconnection from supply lead (microwaves usually have fixed lead)

C) Physical disconnection from mains outlet (probably inaccessible due to inset cabinet).

D) Approved mains outlet switch (your only remaining option).

Yes @neb same goes for all those other appliances. The approved user manuals will all contain a clause to the effect of:

"To turn this apparatus off completely, you must disconnect it from the wall outlet. Consequently, the wall outlet and power plug must be readily accessible at all times."

MikeB4

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#1624808 6-Sep-2016 20:57

We have an electrician coming tomorrow to quote, I will take into account all that's been said here and what the electrician says, he is the professional and will see first hand what

The install is.

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