100amp fuse 16mm tails

[growler]

can anyone tell me why some houses are fitted with 100amp fuses and only 16mm tails ? was this how they did it back in the day ?

 

[Plonker 3]

Are you sure that it is a 100 amp fuse fitted, and not just what the label says on the holder?

 

[Dizzy_Maskell]

Yes I have seen many that turn out to be 60 Amp after getting DNO to verify

 

[Octopus]

There are masses of homes with 100A fuses and 16mm tails.

Thats why I nearly always leave them in place

 

[growler]

Are you sure that it is a 100 amp fuse fitted, and not just what the label says on the holder?

was thinking this might be the case

 

[growler]

There are masses of homes with 100A fuses and 16mm tails.

Thats why I nearly always leave them in place

why no upgrade of tails ?

 

[Octopus]

why no upgrade of tails ?

If there is no sign of "wear" and the anticipated max demand of the property is 40ish amps why bother.

Just because the OSG shows 25mm doesn't mean you have to upgrade them.


New installs and rewires 25mm are required.

 

[7029 dave]

16mm tails are rated approx 90ish amps, short length, 3mtrs max (top end), if its an old cu 60amp dp switch doubt you would get 25mm in the terminals anyway.

 

[peterb]

The requirements changed starting about 1980 IIRC shortly following the standardisation on 100A main fuse. Before then 40A 60A and 80A fuses were all common (increasing in holders marked 100A) and many meters were only rated for 60A or 80A. 15th Edition followed as did upgrade of bonding and earthing conductors. Objective was rumoured to be to cut the number of blown main fuses following the widespread takeup of electric showers.

 

[davethsparky]

If it is not possible to change the tails without making a complete and utter mess of someone's house then i'll do it, but if the only way is to go surface in trunking through a habitable room then i'd rather leave the 16mm unless absolutely necessary.
The normal case is consumer unit in the porch high level with the meter box on the same wall externally with the tails in the cavity at daft angle and coming up into the roof void and back down into the CU. Only sensible way to get new tails up is trunking inside or taking the roof apart to get above and pull the new tails up the cavity.

 

[7029 dave]

The requirements changed starting about 1980 IIRC shortly following the standardisation on 100A main fuse. Before then 40A 60A and 80A fuses were all common (increasing in holders marked 100A) and many meters were only rated for 60A or 80A. 15th Edition followed as did upgrade of bonding and earthing conductors. Objective was rumoured to be to cut the number of blown main fuses following the widespread takeup of electric showers.

Some old dial meters are only rated at 40amp

 

[amlu]

never heard of tails or meters going in flames. looks like dno knows what they doing.

is more of dodgy consumer units or sockets giving problems.

 

[Engineer54]

Never seen 25mm (Copper or Aluminium) tails in any of our European cousins domestic installations!! In fact if you did have a 100A supply with 25mm tails you'll be paying a large premium on your standing supply and electrical unit cost, in most, if not all European countries. You wouldn't believe what most domestic homes actually run on, in terms of KW on the continent and beyond!!

My house in Cyprus is supplied via overhead supply and into my service cut-out and meter cupboard in 10mm aluminium cables

 

[Knobhead]

Connect a length of 16mm² tails to the output of a good welding set. Turn the current to 300A+ and see what happens. It’s boring!

 

[kingeri]

I've also noticed that recently the DNO, when replacing meters around my area, is replacing the 100A fuses with 80A anyway. 'Upgrading' from 16 to 25 would truly be waste of copper in most cases.