# Low Wattage Microwave oven



## 97357

We want to get a microwave oven for the van. 

What do you think - a low wattage one or a normal one. We will mostly be using campsites with hook up, is there any point to a low wattage micro?

Thanks

Friday


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## Rapide561

*Hi*

Hi

My new van has a 750 watt mircrowave pre installed. From a previous post I did, 750 watts is just over 3 amps.

Given that on the sites I have used I have run a 2000 electric heater, then the microwave should nt be a problem.

I suspect both items would not work at the same time.

Another issue might be cost. A domestic "nothing fancy" microwave will set you back about £20.00 or so. I suspect a low wattage one from a camping shop etc would cost a lot more.

Rapide561


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## 88862

Aldi were selling a combined 850W microwave, 1400W grill with a 1000W convection oven for around £65


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## sallytrafic

Just two things to be careful of. A '750 Watt' microwave refers to the power of the microwaves not the input power.

For example my Sharp 850W is input rated at 1.5kW. This is because the conversion from electrical power to microwaves in the magnetron and supporting power supply is only about 60% efficient. 

2nd problem they are not soft start devices and the power drawn when the magnetron kicks in may momentarily exceed the rated power. I have tripped a 10A breaker with a microwave.

Sorry to disillusion you

Regards Frank


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## Rapide561

*Microwave*

Hi

Very interesting Frank.

It just goes to show that either

a) Everything is not what it seems

or

b) Rapide's understanding of electricity etc is pants!

Rapide561


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## 89555

I bought a 12volt microwave some years ago and never used it! mainly to the various complexities in wiring the oven into the 12 volt system (I am a thickie) but I am a gadget man. I decided to use a normal micro on hook-up. The 12volt micro was of little use to me and sold it on Ebay
Another point was the huge drain on the 12volt system on startup which I was warned of
I find that the use of a microwave oven in a van is minimal and heavy to carry around, so I am currently back to basics ..Oven/hobb 
Jack Kelly


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## 96783

Basics? What's basic about an oven and hob? Basic is a camp fire and a billy can with the fire lit with either two sticks or one match! Were you never a boy scout in the days when scouting was done in Bell tents or worse and all cooking was done on a camp fire with a biscuit tin as an oven?


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## zaskar

PhredC said:


> Basics? What's basic about an oven and hob? Basic is a camp fire and a billy can with the fire lit with either two sticks or one match! Were you never a boy scout in the days when scouting was done in Bell tents or worse and all cooking was done on a camp fire with a biscuit tin as an oven?


and 6 of us lived in a shoebox in the middle of the M1

........AN' THAT WERE LUXURY!!!!!!!!!!!!!!!!!


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## 88724

Normal one

Zasker thats nothing

I had to get up in the morning at ten o'clock at night,
half an hour before I went to bed........................................, 
eat a lump of cold poison, work twenty-nine hours a day down mill, 
and pay mill owner for permission to come to work, and when we got
home, our Dad would kill us, and dance about on our graves
singing "Hallelujah."

But you try and tell the young people today that... and they won't
believe ya'.


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## 89555

Not wanting to change the thread I was a relation of Baden Powell well at least we did greet one another with a left hand shake and I did rub two sticks together, to make a fire and cook my damper, but I now live in the luxury of a motorhome. Strange how times can change in one's life time


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## 97357

Thanks very much for the replies.

We have no oven, but we do have a 3 year old who doesn't understand time. If she wants something hot, she wants it now!! Hence the microwave question. We have a 300w inverter but the low wattage micro wave oven we were looking at is 500w so I think we will look for a normal one. We can work around the odd time (hopefully) we wont be on hook up.

Thanks again.

Friday.


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## 88724

Hi Friday

Maplins are doing the 1000w invertor for £69 at the moment, this should easily power a 500W microwave ( they are typically 50% more input mains power required than the ( output) cooking power )


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## 97357

Ah dont sicken me. We are in Ireland. We just bought a 300w for €99. The 1000w was four hundred and something euros. Ah well.


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## daveandcarol

Saw a cute little microwave in the CO-OP today for £25.

800w microwave power, 1050w input power.

Would this be ok to run off 2x 110ah batteries? (through an inverter).

Bye, Dave.


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## cabby

We have a microwave pre-fitted into our van, we have found that it works fine on most sites with hookup.however make sure that very little or even nothing else is also on at the same time. as already stated its the initial startup when the highest amount of current is needed.our 3 year old granddaughter is the same,if its tea time where is it.the novelty of the bar-b-que quickly wears off at her age.


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## 88724

Hi Cabby

Having measured the input on several microwaves, I have not seen a Starting surge worth mentioning. 

Hi Dave

I have run an 800 from my invertor no problem at all (my invertor is a Sterling 1800 Watt though) 

2 batteries will cope with a Microwave


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## sallytrafic

Hi George did you scope the input or use a dvm? The transient overcurrent is short but quite long enough to trip a breaker. Of course the technology is improving so I'm not surprised to see a 800W that only draws 1050W perhaps they are making soft start as well now.

Regards Frank


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## 88724

Hi Frank

A Digital Voltage Meter, but even going through a 6 A breaker mcb, it never tripped. possibly the reason's for this are that breaker's usually are specced at 3 to 5 times higher than their nominal current for a few seconds (see footnotes) and also that in reality its wattage that causes a breaker to trip and high start currents blips usually cause a voltage drop blip too.....

If you are reading a DVM when a motor or compressor starts up you can see the start up power, its usually high enough and drags on for more than an instant.

*Footnote* on mcb tripping loads, for Type B and Type C mcb's, these are the usual types fitted (I have never actually seen any other type, D's exist, but I have never found reference to a Type A)

Type B characteristic offers instantaneous short circuit response level of *3-5 x normal rated current,* making it suitable for circuits with moderate inrush currents such as filament lamps, heating loads and most domestic/small building protection applications.

Type C characteristic offers short circuit response of *5-10 x normal rated current,* making it ideal for circuits with higher inrush currents such as motor control and fluorescent lighting installations in industrial buildings where nuisance tripping might occur if a faster type was used.


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## Enodreven

Hi, Just another point to watch is if you intend putting the microwave in a cupboard ? the ones with the combined Grills or Convection ovens may not be sutitable due to the heat generated ?


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## sallytrafic

GeorgeTelford said:


> Hi Frank
> 
> A Digital Voltage Meter, but even going through a 6 A breaker mcb, it never tripped. possibly the reason's for this are that breaker's usually are specced at 3 to 5 times higher than their nominal current for a few seconds (see footnotes) and also that in reality its wattage that causes a breaker to trip and high start currents blips usually cause a voltage drop blip too.....
> 
> If you are reading a DVM when a motor or compressor starts up you can see the start up power, its usually high enough and drags on for more than an instant.
> 
> *Footnote* on mcb tripping loads, for Type B and Type C mcb's, these are the usual types fitted (I have never actually seen any other type, D's exist, but I have never found reference to a Type A)
> 
> Type B characteristic offers instantaneous short circuit response level of *3-5 x normal rated current,* making it suitable for circuits with moderate inrush currents such as filament lamps, heating loads and most domestic/small building protection applications.
> 
> Type C characteristic offers short circuit response of *5-10 x normal rated current,* making it ideal for circuits with higher inrush currents such as motor control and fluorescent lighting installations in industrial buildings where nuisance tripping might occur if a faster type was used.


Always used type Ks myself as it was company policy to use one type across the service and they were absolutely essential afloat but I agree they are closer tolerence than Bs.

As you know not all dvms were created equal (especially the sampling period) I once had a high end Fluke that took a second to settle it missed all transients.

My Sharp's transient when viewed on a scope exactly matches the grunt noise it makes as the magnetron is switched off and on. Still its nearly 14 years old now so perhaps the technology has come along a bit.


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## JohnDough

sallytrafic said:


> Just two things to be careful of. A '750 Watt' microwave refers to the power of the microwaves not the input power.
> 
> For example my Sharp 850W is input rated at 1.5kW. This is because the conversion from electrical power to microwaves in the magnetron and supporting power supply is only about 60% efficient.
> 
> 2nd problem they are not soft start devices and the power drawn when the magnetron kicks in may momentarily exceed the rated power. I have tripped a 10A breaker with a microwave.
> 
> Sorry to disillusion you
> 
> Regards Frank


Yes absolutly correct they are too heavy on juice and also just to plain heavy!! I always use a combi oven with grill as at most you are only using approx 1000 watts at a time and even on 6amp sites never kicked out the trip but if you keep it at this all should be ok and VERY light.

BTW best thing I ever bought was a 800watt kettle even works off the 1kw Genny!! with all lights fridge and TV going off site.


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## eddied

*Microwaves in motorhome*

:roll: 
Interesting questions and answers, because I've just taken delivery of a used Euro spec. Chausson Welcome 5. No oven of course, which in fact in my experience we don't need/never use. But - still have to tell the wife back in Italy that she no longer has the beautiful oven that we had in our Bessacarr E645. So, looking for a small, low power compromise.
saluti,
eddied


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## 97978

*Re: Hi*



Rapide561 said:


> My new van has a 750 watt mircrowave pre installed. Rapide561


How it is prefitted? Is it secured in its "locker" somehow. Either screwed to the bottom or some type of frame to hold it?

Reason I ask is I am looking to "fit" one in my new Ace Firenze (Swift Sundance 630L / Bessacarr £495)


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