Wax dots on fuse?

[tom21]

I have a fuse in my fusebox which I recently wired to my electric oven. It had been previously used for an electric shower and the cable is good for 30 amps. The oven needs only 15 amps so I changed the rating of the fusewire to 15 amps even though the fuse holder designated it to be a 30 amp fuse. I've since pulled the fuse out as I noticed that one of the two red wax like dots on the face of the ceramic fuse seemed to have melted. The fuse wire is still fine. Does anyone know what these dots are for and the significance of why they would melt - i.e. what fault this is designed to alert (as it is obviously designed to melt?).

[plugwash]

a picture would help

are you sure it was meant to melt and that its not a sign of overheating?

[Taylortwocities]

They are not supposed to melt. They are just seals over screws that fix the fuse wire & plug part of the fuse itself.

Two things:

1. Its probably just dropped out, if its melted you should investigate the cause - its not supposed to get hot! May be a loose connection underneath
2. Be VERY CAREFUL. The brass screw under the seal is close to the surface and it is LIVE.

Fix the problem and get a new fuse carrier. Put insulating tape over the holes in the meantime.

__________________
TTC

When you get to the end of your rope, tie a knot and hang on. - F.D.R.

[tom21]

I have no picture sorry. It is in a flat I am fixing up.

Pretty sure that the dots are designed to melt - else why would they be there. The fuse is ceramic with four pins and fits into a mating ceramic female shroud - i.e so you cant stick a wrong rated fuse in.

The fuse just takes fusewire and no cartridges.

Bit concerned that it seems to have melted. It is just a single radial circuit to the Oven. A brand new 15 amp rated AEG oven - which seems to work fine. Thing is, I haven't even had the switch to the oven on for more than a few minutes. Just noticed the damaged fuse the other day. Was wondering if it perhaps an indication of a fault with the earth given that there were no RCDs available at the time of installation (it's really old)?

Cable seems in good condition! most of it is brand new!

[Steve]

The dots are there to show visually from a distance what rating the carrier is. red is 30 amps.

[Softus]

tom21 wrote:

It is in a flat I am fixing up.

Are you aware that the work you're doing is Part P notifiable?

Quote:

Pretty sure that the dots are designed to melt - else why would they be there.

You've been told why it's there.

Quote:

The fuse is ceramic with four pins and fits into a mating ceramic female shroud - i.e so you cant stick a wrong rated fuse in. The fuse just takes fusewire and no cartridges.

In which you can wire the cartridge with the wrong gauge and thereby make it wrongly rated.

What cable have you used?

Quote:

Bit concerned that it seems to have melted.

If it has melted then you should be concerned, because it isn't supposed to melt.

Quote:

Just noticed the damaged fuse the other day. Was wondering if it perhaps an indication of a fault with the earth given that there were no RCDs available at the time of installation (it's really old)?

If you don't know what you're dong then you shouldn't be doing it.

If you do know what you're doing, then please explain how an earth fault would lead to overheating of the fuse carrier.

Quote:

Cable seems in good condition! most of it is brand new!

Er, most? Have you joined sections of cable?

[JohnD]

Softus wrote:

tom21 wrote: It is in a flat I am fixing up. Are you aware that the work you're doing is Part P notifiable?

"Location: Aberdeenshire"

But ceramic, and four prongs, suggests it is really really really old. Maybe the heating is due to poor contact of the prongs. And melting plastic, on ceramic holders, is a very bad sign. It would be a good idea to get a competent professional in.

[Softus]

JohnD wrote:

Softus wrote: tom21 wrote: It is in a flat I am fixing up. Are you aware that the work you're doing is Part P notifiable? "Location: Aberdeenshire"

I choose to ignore whatever people declare in the location for their username, because so many lie and joke about it.

This is the "Electrics UK" forum - if he's in outside the jurisdiction of UK laws and standards then the topic should be moved to another forum.

Notwithstanding that, the basis for the existence of Part P is safety, and this applies to everyone everywhere, and need for the OP to consider whether or not he's competent transcends location and jurisdiction.

[c128]

Softus wrote:

This is the "Electrics UK" forum - if he's in outside the jurisdiction of UK laws and standards then the topic should be moved to another forum.

...but Scotland is certainly part of the UK, and doesn't Part P apply to just England and Wales?

[Softus]

c128 wrote:

...but Scotland is certainly part of the UK, and doesn't Part P apply to just England and Wales?

You're correct on both counts, but the principles of Part P, i.e. safety and accountability, apply to everyone everywhere. Part P in England in Wales gives householders the right to receive a certificate for all notifiable wok, i.e. work associated with significant risk of injury.

I believe, but wouldn't be able to back this up without some research, that the law in Scotland places the same duty of care upon a householder towards all occupants and visitors. If that householder chose to engage an incompetent electrician, i.e. by not checking credentials and qualifications, then they would thereby be partially culpable, at least morally, if not legally, in the event of any injury to another person.

BTW, I'm pretty sure that Scotland is connected to the England and Wales national grid, so they appear to be having their cake and eating it.

[c128]

Softus wrote:

You're correct on both counts, but the principles of Part P, i.e. safety and accountability, apply to everyone everywhere. Part P in England in Wales gives householders the right to receive a certificate for all notifiable wok, i.e. work associated with significant risk of injury.

I don't think anyone would argue that work shouldn't be carried out safely and in an accountable fashion. However, I'm sure plenty would argue that you don't need Part P to ensure that - at least the Scottish would still seem to think so even if the English and Welsh don't (or can't, at least now).

There seems to be relevant point in this though...it's a UK forum, and the legal requirements aren't consistent across all of the UK i.e. it's neither wrong, nor illegal, to perform what would be notifiable work in England/Wales in Scotland - that's surely worth knowing? Of course it's wrong to do unsafe work anywhere .

[Softus]

c128 wrote:

I don't think anyone would argue that work shouldn't be carried out safely and in an accountable fashion. However, I'm sure plenty would argue that you don't need Part P to ensure that...

What we need (sic.) is for customers to be less skinflinty about engaging qualified tradespeople. What many people appear not to realise is that safety is the responsibility of the householder, not the tradesperson, or the government, or their mum, or anyone else.

Part P has formalised a means by which any householder can be provided with a certificate of safety. For a householder who always acted responsibly the change is small, but for people who used to pay as little money as possible, they are now prevented (in law) from having a rubbish job done on the cheap.

The problem has always been that cowboy tradespeople have exploited the uneducated and the greedy, so in Scotland the former are not protected against the unscrupulous, and the latter aren't prevented from endangering everyone else.

[JohnD]

Scots law is different from English law.

Not necessarily better or worse.

Scotland has a system of Building Warrants instead of Part P and others.

Incidentally, some of the National Grid is fed from the Scottish Hydro.

[c128]

Softus wrote:

The problem has always been that cowboy tradespeople have exploited the uneducated and the greedy, so in Scotland the former are not protected against the unscrupulous, and the latter aren't prevented from endangering everyone else.

...and, in solving this problem Part P imposes the regulation inspection expense of work that folk wish to perform on their own homes, including some things that really are quite trivial (not to mention contradictory).

I'm all for the regulation of cowboy tradespeople. I would, however, like to be able to perform electrics on my own property up to my own level of competence without hindrance and unnecessary expense. I realise these are difficult scales to balance, but I'm unclear as to what problem Part P was aiming to solve in this context, as it does apply in this context (and it's the context where the OP came in, with a query about work on their own property).

[Softus]

c128 wrote:

...and, in solving this problem Part P imposes the regulation inspection expense of work that folk wish to perform on their own homes, including some things that really are quite trivial (not to mention contradictory).

If you disagree with the principle of Part P, then you should write to your MP about it.

If you disagree with the definition of notifiable work, then you should write to your LABC and to your MP.

Quote:

I'm all for the regulation of cowboy tradespeople. I would, however, like to be able to perform electrics on my own property up to my own level of competence without hindrance and unnecessary expense.

Well, the problem is that most people sell their properties and have family living there and people visiting. You can risk your own life, but Part P serves to protect those around you. If you live alone in a detached house, without visitors, and never sell it, then Part P has dealt you a poor hand, but that's the nature of legislation - you can't please all of the people all of the time.