• The forum software that supports hummy.tv has been upgraded to XenForo 2.3!

    Please bear with us as we continue to tweak things, and feel free to post any questions, issues or suggestions in the upgrade thread.

Fuses

prpr

prpr

Well-Known Member
Why is the fuse in the HDR mains plug 5A ? The preferred values these days seem to be either 3A or 13A.
The cable on the device is really not very thick. Why did they not put a 3A in there? 1A is plenty.

Some odd pricing from CPC for a pack of 10:
5A £2.36
2A £2.53
7A £2.54
10A £4.88
3A £5.26
13A £5.34
1A £6.38
 
prpr said:
Why is the fuse in the HDR mains plug 5A ?
Click to expand...
No idea. Most of my Humaxes don't have a fuse in the plug - the plug is a fuseless transformer.
My 9150T has a plug - with a 5A fuse.
prpr said:
Some odd pricing from CPC for a pack of 10:
Click to expand...
That could be your answer. If a 5A fuse is less than half the price of a 3A/2A fuse and much cheaper than a 1A one, cost rather than protection! A bean counter has probably decided that the cheapest components are best.
 
The fuse in a UK mains plug is there to prevent over-current from setting fire to the cable, and has little to do with protecting the equipment itself. The equipment should be fitted with its own internal protection (fuse, PTC thermistor, whatever).

The key factor in determining the maximum rating for the plug fuse is the continuous current rating of the mains cable.

I have seen Chinese imports with a 3A flex (if that) fitted with a 13A fuse.

I suggest Toolstation or Screwfix for packs of non-13A fuses.

EEPhil said:
A bean counter has probably decided that the cheapest components are best.
Click to expand...

That would not cut it with compliance agencies.
 
Well so it is! Just swapped mine for a 2A RS Components one from the 1980s held in my Stores.

On my one it is 2x0.75 sq.mm cross-sectional area 'light duty' cable. That cross-sectional area is rated to 6A so the 5A protects the cable fine.
Manual says "protected by internal fuse" so that's also OK then ;)

Pricing may be to do with Stock turnover and re-ordering purchase costs; or even their quantity purchase discounts? RS has similar 'odd' pricing for them https://uk.rs-online.com/web/c/fuses-circuit-breakers/fuses/cartridge-fuses/?selectedNavigation=attributes.Fuse_Size=6.3 x 25mm

EDIT: The Humax 5A fuse was branded Bussman - so not the cheapest possible fuse to fit originally.
 
EEPhil said:
My 9150T has a plug - with a 5A fuse.
Click to expand...
So do my 9200s. And an old Panasonic. The other old one I put the plug on myself (for whatever reason I can't remember) and obviously has a 3A fuse.
If a 5A fuse is less than half the price of a 3A/2A fuse and much cheaper than a 1A one, cost rather than protection! A bean counter has probably decided that the cheapest components are best.
Click to expand...
But why would they be more expensive to produce? As BH points out, Screwfix and Toolstation do them for the same price. I can't believe the price differential is as great as CPC's for the vast quantities that manufacturers must buy.
Black Hole said:
The key factor in determining the maximum rating for the plug fuse is the continuous current rating of the mains cable.
Click to expand...
Indeed, so what do we reckon about the HDR's cable (the other models use the same)?
 
prpr said:
Why is the fuse in the HDR mains plug 5A ? The preferred values these days seem to be either 3A or 13A.
The cable on the device is really not very thick. Why did they not put a 3A in there? 1A is plenty.
Click to expand...
The fuse is to protect the cable, not the HDR Fox T2. I find 3A and 13A very rare these days and the common sizes are 5A and 10A, so I must be buying different gear to you. The cable is probably 0.75mm2 flex and 5A is fine for that. It's 3A for 0.5mm2 flex if I remember correctly.

EDIT: the rise of 10A rated gear may be because European 220V sockets are max 10A. I only see 13A fuses on UK spec kettles and extension leads these days.
 
Last edited:
Rodders53 said:
On my one it is 2x0.75 sq.mm cross-sectional area 'light duty' cable. That cross-sectional area is rated to 6A so the 5A protects the cable fine.
Click to expand...
Much obliged.
my Stores.
Click to expand...
One of my ex-colleagues (now erecting daisies) use to refer to Stores as the free shop at the top of the wooden steps.
Owen Smith said:
The fuse is to protect the cable
Click to expand...
Yes, I know! I never said it wasn't. I never even mentioned the unit itself in post #1 - just its cable.
 
Interestingly the original intent was clearly for 3A on light loads and 13A on heavy loads, since 3A fuses are red and 13A fuses brown for easy identification. All other ratings are black, which covers 5A, 7A and 10A for 13A plugs. 1A isn't a rating I have ever seen for 13A plugs, and for shaver adaptors the fuse is a different physical size.
 
You must log in or register to reply here.
Back
Top