New Heated Towel Rail blows fuse...

[Rodtheplod]

Look closely for any tiny nicks in the insulation of the wires.

The only thing near that is on the live cable coming out of the heater flex which connects to the live pole in the flex outlet. Its only on the surface of the plastic sheathing, though. I think I did that when cutting the main sheathing down.

However, no actual wire is exposed so I don't think that would pose a problem.

R.

 

[bernardgreen]

The live 2.5mm is damaged just where it comes out of external sheath, you can see the black scorch marks.

Hey Swampy2 - thanks for checking the pictures. Actually, thats just how the picture has come out - shadows or something caused by the flash.
In reality, the live cable is fine. No scorch or burn marks at all.

I agree with swampy. That live coming into the back box looks as if there are deposits consistent with damage inside the sheath.

The alternative to there being a fault in the cable coming to the cable outlet is that the new towel rail is defective. Do you have access to a multi-meter to test the resistance ( Live to Neutral and Live to Earth ) in the towel rail ( after you have dis-connected it from the mains )

 

[ban-all-sheds]

Or a faulty appliance - do you have a multimeter?

No - I don't have a working multimeter. I can get one tomorrow though. What should I be checking for?

Low resistance between L & N.

Or between L & E if the circuit has no RCD.

 

[slippyr4]

Don't go to tesco to buy fuses, go to maplin and buy a cheap multimeter.

A pack of fuses is not a test device.

 

[slippyr4]

Live insulation damaged by the faceplate screw? L-E fault only when the plate is screwed back down?

 

[Rodtheplod]

Don't go to tesco to buy fuses, go to maplin and buy a cheap multimeter.

A pack of fuses is not a test device.

Quite right .

OK - I made sure that all connections were good inside the flex outlet box.

I actually found a pack of four fuses so used one of those. I turned the unit on and this time the switch in the consumer unit didn't flick - so I thought I was home and dry.

But 20 mins later the towel rail was still stone cold. Sigh. So I took the fuse out out of the fused connection unit and popped it in the plug for the kettle to test it. Sure enough it has blown.

OK - I have a Wickes and Homebase just 15 mins away so I'm going to pop to one of those now and pick up a multimeter....

R.

 

[slippyr4]

The switch the trips in the consumer unit - is it an red or an mcb? What does it say on it.

 

[Rodtheplod]

The switch the trips in the consumer unit - is it an red or an mcb? What does it say on it.

I can show ya!

In the cupboard containing the consumer unit, there are actually two boxes. The first one has been there since day dot I guess, and contains the switch that trips. The second one was put in when I had an extension fitted around 8 years ago. This is when the downstairs toilet (containing said towel rail) was converted into a bathroom/shower room as well.

Anyhow, here is the original unit (apologies for the dustyness of it!):

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• Rodtheplod
• 28 Nov 2013
• 1

The switch that trips is the third one in. It's labelled "Power Back of House":

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• Rodtheplod
• 28 Nov 2013
• 1

This is the newer unit. None of these switches are affected, but just including this image to give you the complete picture:

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• Rodtheplod
• 28 Nov 2013
• 1

Cheers!

R.

 

[ban-all-sheds]

So it's not an RCD tripping, which means that the fault is L/N or L/E.

As an aside - you should consider having an electrician populate the spare ways in the newer CU with RCBOs, and moving as many circuits as possible onto them. Certainly any socket circuits, and the one supplying the shower room.

 

[riveralt]

Have you determined that the 'ebay' product is not causing the fault?

Put the cable from heater into a 13A plug and try it in a socket or suitably rated extension cable.

If it works then your problem lies with your household wiring - if nothing else on the circuit has been moved or altered and you have wired everything correctly then the fault would probably occur at the weakest point - normally at a terminal either in the FCU or the Consumer Unit.
If nothing is obvious at the termination points then your only option is to either carry out dead circuit tests and/or live tests if you feel competent and confident to carry them out.
Alternatively get an electrician in to help sort it out.

 

[Rodtheplod]

Yes, I have a feeling its the towel rail itself that's faulty

OK - I now have a £15.99 multimeter from Homebase. Where do I stick it?! (yes - I've considered the eBay seller).

I guess I should read the instructions.... and I'll probably end up sending this towel rail back, or getting an electrician out - which will be annoying if its the rail that's faulty as I'll have to pay call out fees, etc.

R.

 

[PrenticeBoyofDerry]

Did you remove the faceplate of the fcu?
You may have nicked a cable there also, on the load side.
But looking at your photos, I would tend to agree with other forum members, it does look like there is a nick in the brown core close to entering the backbox, also looks to be discolouration at that point on the backbox.

 

[swampy2]

Switch off the FCU and pull on each twin & earth core.

 

[Rodtheplod]

OK, so with my new multimeter I tested the resistance in the towel rail.

I set my multimeter to the ohms setting and put it at 2000K. At this setting, the screen reads: 1.

• 
  * The Live to Neutral fluctuates around 003, 004, 001, etc.
  
  * The Live to Earth does nothing. It sits at 1 and doesn't move.

Is that what you'd expect to see?

R.

 

[Rodtheplod]

Did you remove the faceplate of the fcu?
You may have nicked a cable there also, on the load side.
But looking at your photos, I would tend to agree with other forum members, it does look like there is a nick in the brown core close to entering the backbox, also looks to be discolouration at that point on the backbox.

Nope - I've not touched the fused connection unit at all, apart from turning it on and off there, and replacing the blown fuses! I don't think the problem is there.

And just to clarify, the cables/brown core in the back box are fine. The phone/flash I took the pictures with seems to have done funny things with the colours, but I've inspected the cables closely and they are not damaged. There's no sign of discolouration or burning, etc.

The dark residue you see at the bottom of the back box is not burn marks or anything like that. It's simply dust and crud. I've actually cleaned it all out now and it looks squeeky clean. Well as clean as a backbox like that can look anyway!

R.