Kettle style lead getting very hot on the plug terminals

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chris2012
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Kettle style lead getting very hot on the plug terminals

Post by chris2012 » Tue Apr 23, 2019 3:56 pm

I use a kettle lead to power my HLT, a peco services, bucket with a 2.4kW element.

This happened the other day:

Image

I found there seems to be a type of kettle lead designed for powering hot appliances. I'm going to have to get one of those
from Peco.

Anyone else experienced a plug getting very hot before like this? I'm not sure what's the difference between 'hot' designed leads
and 'cold' ones. I was thinking could the heat from the element be able to travel through the copper wires through conduction?

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Re: Kettle style lead getting very hot on the plug terminals

Post by guypettigrew » Tue Apr 23, 2019 4:33 pm

Oooh, that's nasty. At 2.4kW you're at the top of the range for the Inkbird, although that doesn't explain why the socket has melted!

You've probably had a dodgy connection between the plug and the Inkbird socket, but it's surprising it's melted both the live and neutral. It must have got very, very hot!

You'll need to replace the double Inkbird socket--shouldn't be too difficult. And you'll need to get a mains lead with a good quality plug. For both of these make sure the cabling is properly tightened inside the socket and plug. Wobbly wires can cause arcing and lots of heat.

The hot condition leads you've seen are all about the other end of the cable, the end which plugs into your kettle element. Not the three pin plug end. Here's a bit of an explanation.

Guy

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Re: Kettle style lead getting very hot on the plug terminals

Post by Jocky » Tue Apr 23, 2019 8:05 pm

The Inkbird really wasn’t designed to take 2.4kW.

I do find the pins on the hot rated leads I have get hot when used for a more than an hour. Appropriate sockets should be able to take it, but the Inkbird isn’t built to that spec.

If you want to use an Inkbird then really you need it to switch a box with a beefy relay in it.
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Re: Kettle style lead getting very hot on the plug terminals

Post by chris2012 » Tue Apr 23, 2019 8:15 pm

Thanks guys! I'm definitely not going to use one again with my HLT I'll either use a PID + SSR maybe, or just turn it on/off manually.

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Re: Kettle style lead getting very hot on the plug terminals

Post by guypettigrew » Wed Apr 24, 2019 9:03 am

My HLT is controlled by one of these.

Expensive and out of stock at the moment. Apart that, perfect!

Guy

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Re: Kettle style lead getting very hot on the plug terminals

Post by alexlark » Wed Apr 24, 2019 8:31 pm

I've been using this cable for the last few years without issue. Much beefier than the standard one:
https://rover.ebay.com/rover/0/0/0?mpre ... 0942526638

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Re: Kettle style lead getting very hot on the plug terminals

Post by guypettigrew » Wed Apr 24, 2019 8:51 pm

alexlark wrote:
Wed Apr 24, 2019 8:31 pm
I've been using this cable for the last few years without issue. Much beefier than the standard one:
https://rover.ebay.com/rover/0/0/0?mpre ... 0942526638
Depends what you're plugging it into. The problem isn't the cable, it's the socket. In the OPs case, the Inkbird controller's output double socket probably isn't designed to carry 10 amps on a long term basis.

Guy

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Re: Kettle style lead getting very hot on the plug terminals

Post by Kev888 » Thu Apr 25, 2019 10:02 am

The inkbird isn't specified for 2.4kw IIRC so you probably can't officially blame it. But personally i wouldn't like to see trailing sockets of that kind used on any powerful element for sustained periods - best suited for lower powered things like fermentation chambers and keggerators really.

It looks like there was a dodgy contact though, and this can be initially caused by the 13amp plug as well as the socket. In any case the plug may have been damaged by this, so I'd swap it for a quality new one before plugging it into any new controller. Avoid cheapo imports or unknown sellers for this kind of thing, the BS codes and kitemarks etc on plugs/leads can be a tissue of lies. Ditto for fuses too, which can overheat if not properly made.

Also might be worth doing what you safely can to check the electrics of your HLT, in case a fault elsewhere might have led to drawing too much current. I wouldn't necessarily expect one though, sockets/plugs can do this without any help.
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Re: Kettle style lead getting very hot on the plug terminals

Post by chris2012 » Thu Apr 25, 2019 1:51 pm

Yeah I don't blame the Inkbird, as it definitely got pretty hot even in an MK socket I have too. I'll now only use them for my ferm chamber.

I'll make sure to get a new cable + plug from a reputable supplier. That's an interesting note about fuses too.

I will inspect the HLT too, although it's just an element with the kettle style connector on it.

Guy - that controller looks nice, but a bit pricey for me alas, I have a PID + SSR already, but it's not very safe at the moment, as it's not in a nice box.

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Re: Kettle style lead getting very hot on the plug terminals

Post by themadhippy » Thu Apr 25, 2019 3:14 pm

Any plug and socket will get warm,theirs a resistance between contacts,all be it very small,and a current, with a 0.1 ohm contact resistance and a 13A current you've got 17 watts of heat being produced.The maximum allowable temperature for a uk socket according to the BS standards is 52C so dont worry to much if there getting warm.
As for the sockets used on the inkbird i very much doubt they 've ever heard of BS standards,even before the manufacturer adapted them,and any ce mark means Chinese Export not conformite europenne
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Re: Kettle style lead getting very hot on the plug terminals

Post by chris2012 » Thu Apr 25, 2019 7:22 pm

That's interesting about the 17W heat being produced, I'd not have thought of that before.

By 0.1 ohm contact resistance, what do you mean btw? I assume that's not just the resistance between live/neutral, as that'd include the element resistance too?

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Re: Kettle style lead getting very hot on the plug terminals

Post by themadhippy » Thu Apr 25, 2019 10:15 pm

The contact resistance is the resistance between the pins of the plug and the contacts of the socket,the worse/higher the contact resistance the greater the heat produced .
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Re: Kettle style lead getting very hot on the plug terminals

Post by chris2012 » Thu Apr 25, 2019 10:32 pm

Ahh, gotcha, thanks!

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Re: Kettle style lead getting very hot on the plug terminals

Post by Kev888 » Thu Apr 25, 2019 10:49 pm

chris2012 wrote:
Thu Apr 25, 2019 1:51 pm
I'll make sure to get a new cable + plug from a reputable supplier. That's an interesting note about fuses too.
Theres an interesting comparison of ebay fuses here which helps give an idea of some things to look out for. I've also seen websites showing moulded plugs with ridiculously feeble conductors inside, and fuses that aren't actually in the circuit!

I suspect the vast majority of ebay FOTEK SSRs are also fake these days too. Originally the fakes were just around half the power rating. Then I think they realised few buyers used them above about 10A whatever the sticker rating. These days they can be almost anything, and the old threads on how to spot fakes are pretty obsolete. A bit sad really, because the SSRs direct from fotek are said to be pretty good.
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Re: Kettle style lead getting very hot on the plug terminals

Post by chris2012 » Fri Apr 26, 2019 12:18 pm

That website is really useful, thanks! I didn't realise fuses are filled with sand either.

I bought a bunch of SSRs a while ago, I'll have to see if they're actually ok.

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