New Microwave Oven, Red Hot???

[ladybirder]

I've taken delivery of a Sharp R272KM Solo 20L 800W Microwave Oven. I used it to heat something for 4.5 minutes and the outside roof and sides were red hot. This didn't used to happen with my previous Sharp oven.

Any idea what, if anything, could be wrong? Cheers.

[ladybirder]

Bump.

[Hymie]

Define 'red hot'

[jennyjoan]

RETURN ASAP

[Ringlet]

I would be returning that microwave straight away. Sides and roof should not get hot. Maybe slightly warm but something wrong if it is too hot to touch

[ladybirder]

Red hot is probably a bit of an exaggeration but it's really hot. I've never noticed that before on my old one.

[Hymie]

It should not get too hot to touch – you need to make sure you have followed the instructions with regards spacing requirements at the rear and sides of the microwave.

[mallyh]

we had this happen(not sharp) phoned the company and returned it ,replacement was fine

[Barmaid]

First of all, read the instructions. It might be that it gets hot.

It might also be worth googling that model.

[ladybirder]

There is plenty of room at both sides and above but could probably be moved further away from the plug socket behind. I'll try that in the morning and see if it still gets hot. If it does I'll phone the company. Recycled all the packaging which is annoying now.
Thank you all.

[ladybirder]

Thanks, I did and am still reading the instructions bm. And I googled it before I bought it as I usually do with new purchases. It wasn't 5* but not far off. My last one was same brand and was brilliant. It might be me, it often is:-( I'll move it a bit tomorrow and try again.

[Peter Pedant]

It might be that it gets hot.
no - actually it shouldnt
it is protected by the wire mesh ( Faraday cage) and if it is heating it means the cage is at fault

and I wdnt have a leaking microwaves in the house actually

even if the skool-leeva at the end of the faults line phone says
" yeah foo it OK - ah fink" I wd return it

[Togo]

//It might be that it gets hot.
no - actually it shouldnt
it is protected by the wire mesh ( Faraday cage) and if it is heating it means the cage is at fault

and I wdnt have a leaking microwaves in the house actually//sic

Don't pay any heed to that bunkum Lady. Microwaves cannot pass through metal. They will pass through glass and that is why the door (Glass) has the dot matrix metal shield built in. You can see in but the microwaves cannot get out. I would think that the case got hot purely due to conductance of heat from whatever you were heating. 4.5 minutes is a fair old amount of power at 800 watts. WE have a Sharps microwave (950W) which is a replacement for a previous Sharps, they are a reliable machine. However like all things modern they do suffer from the drive to reduce costs and like any other brand you care to mention the build quality and attention to detail has been eroded. The gauge of metal used is not as heavy or rigid as it once was and any surplus insulation (inside the casing) has been reduced to a minimum. The manufacturers also in their wisdom saved money long ago by reducing the thermal heat conductance barriers that were part of the chassis build. I think that you will find that the machine is operating as it should. You can do a sneaky check to test if the oven is safe. UNPLUG it. Now place a mobile phone inside and oven cavity and call the number from your land line or another mobile. If the phone cannot be called the oven is definitely safe. However some of the very modern mobiles that are using 4 and 5g may get a signal and this does not mean that the oven is unsafe, just that the frequency of the phone signal is outside the microwave bandwidth and therefore not blocked.

[naomi24]

I don't know the ins and outs of microwave ovens but I wouldn't hesitate to send it back and exchange it for another make.

[ladybirder]

Togo, Naomi, all is well thank you. I thought it might be too near the plug sockets so I moved it forwards a couple of inches and lo and behold it is now fine. And after all your trouble of typing that lot out Togo. Sorry.

[Togo]

That would do it Lady. Looking at the user manual there is a row of vents on the bottom along the back edge. The manual also recommends a gap of 20cm (which is about 8 inches) from any adjacent wall and a 30cm gap from the top to say a wall cabinet. Must say that seems to be quite a lot of space but those vents are what help to keep the machine cool as is heats up the contents. A fan blows and vents the cavity of heat and steam to prevent overheating. It does however not prevent overeating. (^_*)

[ladybirder]

True LOL;-))

[naomi24]

Oh, you didn't say you were suffocating the poor thing. That'll explain its protest then. ;o)

[Peter Pedant]

oh deaer Togo seems to have missed this:

As it turns out, the main form of shielding built into the microwave is a device called a "Faraday cage". These types of devices work dissipating the charge from EM radiation around their structure.

how often does Bunkum turn out to be true?

[jennyjoan]

LB - sorry to digress.

Has anybody ever noticed whether on Soaps, reality TV, including my own relatives homes. There are piles of papers, salt, pepper and loads more sitting on the little grid on top of microwave. That alone would blow the bloody thing up.

Back to you LB - I don't think for one minute your moving the microwave away from plugs should cool it down. If it is brand new - send back for another new one. The shop should be able to give another one even tho you don't have the box.

[Togo]

Because microwaves will not pass through metal, the cavity and case itself act like a Faraday shield. They are not a cage which is normally made of a mesh or grid with the mesh size being dependant on the frequency to be blocked. Because of the requirement to have visual contact with the inside during cooking the door has a glass panel. As I explained this does need additional measures to block the waves, hence the built in laminate of a dot matrix screen that makes safe the sixth surface.

"" There is a common misconception that a microwave oven is a Faraday cage. It is not. Not even a close approximation. Look at the mating surfaces between the door and oven. There is no bare conductive metal at all, usually power coated sheet metal or plastic on both surfaces. It is essentially *wide open* from an RF perspective except right at 2.4GHz. Attenuation at 2.4GHz is achieved through the use of metal features inside the door that make the slot between the door and the oven look like a quarter wave reactive choke. 2.4GHz is essentially reflected back into the oven from the door/oven seam. This is why the door is so thick.""

The door itself acts as a choke and attenuates the microwave beams the cavity size and wave guide from the magnetron being carefully calculated to achieve this . Microwaves will not pass through metal and metal does not need "Faraday cage"protection.

physicsforums.com/threads/microwave-faraday