3kw appliance moulded plug top

[Daz2007]

Hi we have a client who insists on using 3kw induction hobs on their projects. These hobs are used 8-10hours per day and come with a moulded plug top. Safe to say the socket outlets keep melting/burning out. First thought was to remove the plug top and wire via a 16amp commando and appropriate 16amp rcbo (These sockets are wired on their own dedicated radial one radial per socket.) However removing the plug top would invalidate the warranty. The appliance is wired with a 1.5mm rubber flex. Not sure what else we can do with this other than tell the client to buy induction hobs that comes with a 16amp commando in the first instant. What's your thoughts on this? Thanks in advance.

 

[ImpededLoop]

Do the manufacturers instructions state that removing the plug top invalidates the warranty?

They may also state "not for commercial use".

 

[snowhead]

I'm sure that the fact the manufacturers fitting a plug not suitable for the appliance rating / use is more of an issue than cutting the plug off.
However as above, I doubt the hobs are commercially rated or rated for continous use.

I used to do commercial work including Kitchens etc.
Anything over 2kw would sooner rather than later melt the plug /socket.
Part of the problem is the plug being removed before the appliance is cleaned and getting contaminaed with grease or cleaning product.

And 16amp plugs / sockets will melt as well, you need to go bigger.

 

[Daz2007]

I've had a look and can't see anywhere where it says do not cut the plug off. It is a commercial hob.

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[marconi]

A combination I have used (years ago though) to handle 3kW load is a black MK safety plug and an unswitched metalclad MK 13A surface mount socket:

13 Amp MK Safety Plug - Charcoal | MK (646CHA) - https://www.tlc-direct.co.uk/Products/MK0646CHA.html

MK Metal Clad Plus Socket Outlet Unswitched Aluminium K848ALM - https://www.builderdepot.co.uk/mk-metal-clad-plus-socket-outlet-unswitched-aluminium-k848alm?gclid=CjwKCAiArOqOBhBmEiwAsgeLmUbYRmilPQYcrAxwV6UMQka02uxE-vbzsdfvewYJMBlJZltSEhEo7xoC5sAQAvD_BwE

MAke sure the socket terminals for L and N are 'filled' with copper - so Barrymore if necessary - to maximise the thermal conductivity and assist heat transfer away from the socket-plug combo along the feed cable. Note - a Black plug to aid radiation of heat. If possible have a small loop of feed cable in free air.

Might work for you.

 

[pc1966]

A combination I have used (years ago though) to handle 3kW load is a black MK safety plug and an unswitched metalclad MK 13A surface mount socket:

Good though to keep the switch's heat away! Can add a 20A DP isolator switch next to it as needed for safety when cleaning, etc.

@Daz2007 do they need to be unplugged at all? If not then a FCU would allow isolation by switching off for any cleaning, etc, and less risk of pings getting dirty/corroded and overheating as a result.

 

[ImpededLoop]

A combination I have used (years ago though) to handle 3kW load is a black MK safety plug and an unswitched metalclad MK 13A surface mount socket:

Problem is that sockets aren't made as well as they used to be. I doubt there's much brass in them these days.

 

[suffolkspark]

I've had a couple of moulded plugs decimate socket outlets, I had one of a commercial bread oven, and 1 on a "haygain" which basically steams hay bales. Replaced both with new plugs and never had an issue since.

 

[Midwest]

I've had a look and can't see anywhere where it says do not cut the plug off. It is a commercial hob.

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Email the manufacturer/retailor and ask them.

Cutting off Moulded Plug Top from appliance - in - UK Electrical Forum

, Cutting off Moulded Plug Top from appliance, UK Electrical Forum, ElectriciansForums.net Est.2006 | Free Electrical Advice Forum and page_number.

www.electriciansforums.net

 

[Daz2007]

Thanks for all the advice, I'm going to give them a call and see what they say. Guessing this is a common issue and won't be the first to call them.

 

[DPG]

Cutting a plug off does not void manufacturer's warranty, and you are well within your rights to do this. What would you do if the plug got damaged - throw away a grand's worth of appliance?

 

[brianmoooore]

Cutting off a 13A plug won't invalidate any warranty in itself. Connecting the appliance without appropriately sized fuse might.

 

[marconi]

Good though to keep the switch's heat away! Can add a 20A DP isolator switch next to it as needed for safety when cleaning, etc.

@Daz2007 do they need to be unplugged at all? If not then a FCU would allow isolation by switching off for any cleaning, etc, and less risk of pings getting dirty/corroded and overheating as a result.

The other aspect is the metal socket surface and back box to act like a heat sink and radiator.

 

[brianmoooore]

Something's gone very wrong with the design of these things if we have to rely on faceplates and back boxes as heatsinks to use them at their rated current

 

[pc1966]

Something's gone very wrong with the design of these things if we have to rely on faceplates and back boxes as heatsinks to use them at their rated current

I believe it is called "value engineering"

 

[marconi]

OP: One might consider using so-called 'audio grade' 13A plugs and sockets which have silver or gold coated pins - silver and gold being very good conductors of electricity - silver being the better. Just google....

One has to minimise Ohmic heating viz I2R at all interfaces...........in order to achieve reliable long term ampacity.

Ampacity - Wikipedia - https://en.wikipedia.org/wiki/Ampacity

Rated current begs the question .............

 

[brianmoooore]

Does it need the £44.75 fuse ( Hifi Tuning Supreme 3 Copper 13A UK Mains Plug Audio Grade Fuse (Single Fuse) | eBay - https://www.ebay.co.uk/itm/392860669045?ViewItem=&item=392860669045 )

 

[marconi]

Does it need the £44.75 fuse ( Hifi Tuning Supreme 3 Copper 13A UK Mains Plug Audio Grade Fuse (Single Fuse) | eBay - https://www.ebay.co.uk/itm/392860669045?ViewItem=&item=392860669045 )

Of course I do not know if it does nor if anything else I have said earlier might satisfy the client. But the OP has a client who wants a certain thing to be, and if it was me wanting to keep his client satisfied - as the OP seems too - I might say to him I have done some research and we could try these things and if they prove successful then ........

I understand from the opening post this is a repeat customer for the OP whom he aims to please if at all he can.

 

[LastManOnline]

Something's gone very wrong with the design of these things if we have to rely on faceplates and back boxes as heatsinks to use them at their rated current

Yes. It's not that long ago that 3 kw loads were pretty much standard in kitchens and utilities. And there were never any question marks attached to a 13 amp plugtops ability to handle it.

 

[Midwest]

I’ve seen various pictures of burnt moulded plug tops, ones that can’t be messed around with and whose connections should be correctly terminated. Some have been the actual fuse and fuse carry, the cause.

Seems quality cannot be guaranteed.

 

[LastManOnline]

I’ve seen various pictures of burnt moulded plug tops

I, ve never really understood the benefits of them. It prevents us from checking and /or remaking connections. And the number of these plugs I have seen jammed in to low lying sockets with the resulting strain on the lead and socket itself unlikely to be of any benefit to either.

 

[brianmoooore]

Health and Safety is part of it. If a customer can't rewire it, he can't rewire it incorrectly.

 

[nicebutdim]

Health and Safety is part of it. If a customer can't rewire it, he can't rewire it incorrectly.

If they needed to rewire one, they'll just lop the original off and replace it.

 

[brianmoooore]

Ye, but that won't be the manufacturer's liability. Customer modified the appliance.

 

[LastManOnline]

Health and Safety is part of it. If a customer can't rewire it, he can't rewire it incorrectly.

That does sound like a peculiar stance by Health and Safety though. I mean in the UK the"customer " appears to be free to wire whatever he likes? So why should plugtops be off limits?

 

[Midwest]

Good ole JW took apart a defective moulded plug;

 

[Midwest]

Cutting off a 13A plug won't invalidate any warranty in itself. Connecting the appliance without appropriately sized fuse might.

You’ve not read my link

 

[brianmoooore]

Vacuum cleaner leads are a special case. No one could design a lead to survive for long if it gets treated like my wife treats ours. Nothing unusual to find it plugged in two rooms away, lead stretched like a trip wire between various bits of furniture.

 

[DPG]

Vacuum cleaner leads are a special case. No one could design a lead to survive for long if it gets treated like my wife treats ours. Nothing unusual to find it plugged in two rooms away, lead stretched like a trip wire between various bits of furniture.

Indeed. The cordless one we bought last year is one of the best things we have ever bought.