Overheating wires

[toast1]

Have an old copper imersion water heater, in the UK, where the wire from the heater meets the wall socket, it keeps over heating. 

I've gone through a few switches that have burned out from overheating.

Today the connection between the wire coming out of the wall and the wire from the heater started smoking.

 

Any ideas on how to fix this?

We replaced the heating element a few years ago, perhaps it is too strong, or we could turn down the thermostat on the water heater, but that would be difficult in the summer.

Thanks

 

[worgeordie]

If you are in the UK, you are not allowed to do electrical work,

find an electrician and get it sorted ,before your house burns down.

regards worgeordie 

[toast1]

If anyone has anything useful or helpful to say, I'd appreciate their advice.

 

 

PS
The fuse in the modern fuse box, dedicated for the heater, is also quite hot, but burning hot but definitely hot, though it never turns off.

Edited June 25, 2020 by toast1

[Crossy]

Call a sparks!

 

If the immersion is plugged into a regular 13A socket then replacing it with an FCU or simply using a "cooker" (45A) outlet (provided the immersion is on it's own breaker) would be the way forwards, replacing the damaged cable of course.

 

One of these would do the trick https://www.tlc-direct.co.uk/Products/AA45COP.html 3.85 + VAT

 

TLC have loads of alternatives if you need a switch https://www.tlc-direct.co.uk/tcl/search?query=cooker+outlet&Submit=Search

 

What size cable is it that's getting hot?

 

What is the power rating of the immersion (should be marked on the cover)?

 

Contrary to the above, there is no law in the UK to prevent you doing this yourself, but you must be "competant", replacing a damaged appliance flex or power outlet isn't notifiable.

 

[toast1]

Thanks for the info.

The immersion is Titanium 240v 3kw,  230V 2.7kw  TIH 585

 

The wire from the immersion is heavy 3 core, I asked the shop for the correct one for this but perhaps it is not right but it is thick.

There is no plug in the wall, just a wire coming out. 

 

I tried putting imersion heater plugs in there in the past, but they burned out.

 

Right now the wire from the immersion is just connected to the wire from the wall without a connecting socket, just electric tape, but the other day the connection started smoking and burning where the wire from the wall meets the wire from the immersion.

Many thanks

 

 

 

[sometimewoodworker]

15 minutes ago, toast1 said:

Right now the wire from the immersion is just connected to the wire from the wall without a connecting socket, just electric tape, but the other day the connection started smoking and burning where the wire from the wall meets the wire from the immersion.

It’s almost certain that the junction between the house wire and immersion is poor. You, at a minimum need to buy a proper sized “choc block” and use that.

they are available from all the usual electric supply shops

[toast1]

OK, I'll do this,  but how is this different from just twisting the wires together, with electric tape, as it is now?

Thanks

 

[Trillian]

My guess would be that the cable is undersized for the load being placed on it. The smoking burning joint may be that the insulating tape was starting to melt/ignite since this is less robust than the insulating covering of the wire. Perhaps check and see if the rest of the covered wire is also getting hot.

[stouricks]

2 minutes ago, toast1 said:

OK, I'll do this,  but how is this different from just twisting the wires together, with electric tape, as it is now?

Thanks

 

You will be ending up as your user name suggests soon. 

And a 3 kW shower unit in UK will not do much good, most of them are now 6 or 7 kW. Try twisting THOSE wires together.

[Trillian]

3 minutes ago, stouricks said:

You will be ending up as your user name suggests soon. 

And a 3 kW shower unit in UK will not do much good, most of them are now 6 or 7 kW. Try twisting THOSE wires together.

I'd be willing to bet that most bathroom water heaters use the same thin wire regardless of the wattage of the unit. We had a 3kw unit swapped out and replaced with a 6kw unit and the same wire was used.

[toast1]

Thanks Trillian

 

I'll check this and perhaps see if the wire I was given is not correct. 
The wire does not get hot, except at the end where it connects to the wire from the wall.

 

But the connection between the two wires gets very hot and the wire becomes burned out -  which I find very strange.  Not sure why the area where the wires are twisted together should get so hot.

 

Any ideas on this?

Thank you

 

[stouricks]

1 minute ago, toast1 said:

Thanks Trillian

 

I'll check this and perhaps see if the wire I was given is not correct. 
The wire does not get hot, except at the end where it connects to the wire from the wall.

 

But the connection between the two wires gets very hot and the wire becomes burned out -  which I find very strange.  Not sure why the area where the wires are twisted together should get so hot.

 

Any ideas on this?

Thank you

 

Because twisting them together DOES NOT form a good, low resistance connection. Hence the heat, and eventually TOAST.

[Crossy]

Seriously @toast1 you need to call an electrician today before your home burns down.

 

[lopburi3]

As said get help or at the least make good connections - obviously the twist is not working and is sparking where contact is not firm causing it to burn after time.  Below type of connector is just about foolproof and makes very good contact (just make sure wire is bare for the marked length as goes deep into connector).

New version is Wago 221 and much smaller.

Edited June 27, 2020 by lopburi3

[bankruatsteve]

1 hour ago, toast1 said:

OK, I'll do this,  but how is this different from just twisting the wires together, with electric tape, as it is now?

Thanks

 

Larger wire sizes are very difficult to make a good connection by twisting. Gaps can/will arc. Use connector as suggested. 

[sometimewoodworker]

1 hour ago, toast1 said:

OK, I'll do this,  but how is this different from just twisting the wires together, with electric tape, as it is now?

Thanks

 

Twisted wire can make good contact. It’s absolutely clear yours is not.

 

If you have 2, 3, or possibly 4 Cables with a single solid core, and the experience to strip the correct amount of insulation, and to correctly twist them together, and add enough insulation to protect everything it can work.

But since using screw choc blocks only requires you to use a screwdriver to make a good reliable safe connection you should use them.

[sometimewoodworker]

1 hour ago, lopburi3 said:

As said get help or at the least make good connections - obviously the twist is not working and is sparking where contact is not firm causing it to burn after time.  Below type of connector is just about foolproof and makes very good contact (just make sure wire is bare for the marked length as goes deep into connector).

New version is Wago 221 and much smaller.

These connectors can be good but I think that the connection is between a single core cable and a multi stranded cable.
 

In a single core cable they are excellent, with multi strand cable at high amps, less good.

[RichCor]

57 minutes ago, lopburi3 said:

 

New version is Wago 221 and much smaller.

 

I love these things. Ordered the 'generic' PCT-213, PCT-215, and SPL-3 (3 wire pass through) off Lazada (vendor Quality Supply).

 

I've resolved to never use those chock-blocks again.

 

 

 

[toast1]

Interesting. 
The Wago 221 looks good, I'll see if I can get one!

[Daffy D]

I seem to vaguely remember in a former life back in the UK the wire from the emersion heater to the wall connection was special 3 core heat resistant flexible cable.

 

As for the actual size of the wire I can't recall but I never had any trouble with it. 

[lopburi3]

31 minutes ago, sometimewoodworker said:

These connectors can be good but I think that the connection is between a single core cable and a multi stranded cable.
 

In a single core cable they are excellent, with multi strand cable at high amps, less good.

The model 221 is specifically designed for all types of cable - multi and fine strand multi as well as single from my reading.  I am a believer and have only used the older 222 models (and not brand name).

[NanLaew]

2 hours ago, toast1 said:

OK, I'll do this,  but how is this different from just twisting the wires together, with electric tape, as it is now?

Thanks

You ask this and your name is 'toast'?

 

Seriously?

[toast1]

There are some strange people posting sarcastic and rude messages, so many to do with a  made up user name.

 

I appreciate the advice of good and helpful people on this site, as always.

 

It is a pity people with nothing to offer but annoying comments think they need to join in.

 

Edited June 27, 2020 by toast1

[toast1]

Thanks Daffy and lopburi3, I'll check out the wire and make sure its correct - and also that connector!

 

[Dumbastheycome]

Admittedly I only have skipped through the  comments, suggestions in reaction to the issue.

Overall I think Crossy's advice is the most appropriate.

Copper wire  cable is the best most common used in electrical installations. But it is  not  "perfect" in the  sense that it is also vulnerable to damage in  quite  common situations such as  connective arcing and resulting  overheating. Like any  metal it is prone to oxidation and at  points of connectivity that reduces  electrical conductivity. Twisted  wire  connections  between  oxidation damaged wires are a  common source of problems. Approved  connectors  which  in effect "Bite" into  a  wire passing through oxidation layers  usually overcome that  problem. A  DIY solution can be to  scrape  back the surfaces  of individual  connecting wires to  bright  metal   to  create a better surface  contact which may be  a solution  but  not a permanent recommendation.

So in  basic  terms if the  gauge of the cable is appropriate then either/or the appliance attached to the outlet has an issue or the contacts of the  outlet have an issue generating heat  into the  cable  ends , or the cable  connection  to the outlet has experienced poor connection and resulting in arcing and heat damage the approach to a solution would be to replace the outlet (wall socket), trim  back the  cable to fresh  metal (if  available) or alternatively  clean the  metal  contact ends and independently have  the appliance that was originally involved in the problem  checked for issues with the plug or ground leakage.

 

 

 

 

 

[toast1]

Thanks

 

[Crossy]

TLC do the special immersion heater cable by the metre.

 

Your 3kW heater will be pulling about 13A so I'd go for the 2.5mm² version 

https://www.tlc-direct.co.uk/Products/CA2dot5TQ3slash50.html 

at 16A rating the 1.5mm² is on the small side although if it's what you already have it should be OK with the proper connector.

https://www.tlc-direct.co.uk/Products/CA1dot5TQ3slash50.html

 

They also do the Wago 221 connector

https://www.tlc-direct.co.uk/Products/WA413C.html