Protection against overload

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At college today doing 17th edition and discussing part 4 it was mentioned that you could run a cable for less than 3 metres without downsizing fuse/ circuit breaker if the chance of overloading that cable was unlikely.

Did I hear this correctly I am wondering?

Any how, what I am relating this to is the number of occasions I have seen on the old 4 way wylex boards (BS3036 fuses) where an electric shower has been installed on seperate 30 amp switch fuse but 6mm T&E has been connected into the main switch.

I always thought this was against regs and advised customer accordingly.

Your thoughts please?

 
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At college today doing 17th edition and discussing part 4 it was mentioned that you could run a cable for less than 3 metres without downsizing fuse/ circuit breaker if the chance of overloading that cable was unlikely.Did I hear this correctly I am wondering?

Any how, what I am relating this to is the number of occasions I have seen on the old 4 way wylex boards (BS3036 fuses) where an electric shower has been installed on seperate 30 amp switch fuse but 6mm T&E has been connected into the main switch.

I always thought this was against regs and advised customer accordingly.

Your thoughts please?
It isn`t classed as "good practice", esp. in dom. inst.

However, in a large install, with a number of subs, it can be useful.

Generally, for domestic, it can be disregarded. I would point it out to a dom. customer; but not as a fail!

 
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At college today doing 17th edition and discussing part 4 it was mentioned that you could run a cable for less than 3 metres without downsizing fuse/ circuit breaker if the chance of overloading that cable was unlikely.Did I hear this correctly I am wondering?....

...Your thoughts please?
I assume they were talking about 433.2.2 (ii) pg 74 17th.

My understanding of this is....

The general rule is wherever current capacity changes a suitable overload protection device should be installed at the point of changed capacity.

however...

the protective device could be installed within 3m of the change of capacity,

providing there are no branches within that 3m length of cable.

But there should still be the new protection device installed somewhere within that first 3m of cable, it cannot be omitted!

This is to allow for situations where it is impractical to fuse directly at the point of change..

Practice example:-

Ring main circuit...

Alarm system to be installed...

Drill through back of socket in kitchen to cupboard under stairs..

Branch off ring main with 1.5mm but put 3amp FCU at alarm panel within 3m of spur from socket.

Ideally FCU should be a branch in kitchen..

but space not available & would look a mess on kitchen layout!

The risk of overload on this short length of cable is negligible!

(providing some DIY bob don't go adding onto it! :( )

Or similar type scenario!

(p.s. saying that personally with the above alarm example I would branch off with 2.5mm anyway!! :eek: :8})

 
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Any how, what I am relating this to is the number of occasions I have seen on the old 4 way wylex boards (BS3036 fuses) where an electric shower has been installed on seperate 30 amp switch fuse but 6mm T&E has been connected into the main switch.

I have seen this too. :(

 
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At college today doing 17th edition and discussing part 4 it was mentioned that you could run a cable for less than 3 metres without downsizing fuse/ circuit breaker if the chance of overloading that cable was unlikely.Did I hear this correctly I am wondering?

Any how, what I am relating this to is the number of occasions I have seen on the old 4 way wylex boards (BS3036 fuses) where an electric shower has been installed on seperate 30 amp switch fuse but 6mm T&E has been connected into the main switch.

I always thought this was against regs and advised customer accordingly.

Your thoughts please?
What was probably said (or should have), the protective device can go at the load end, as in Special Locations example. The correct size breaker/fuse for the applied load still has to be somewhere in the circuit. I dont like this method much but you could not give an unsatisfactory on a pir for this reason alone (although many wrongly do )

 
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Ok thanks for clearing that one.

Can i just ask what am I suppossed to achieve from gaining the 2382-10?

Is it to have superior knowledge of all elements of the regs or just to know where to navigate and find the required info?

Cant really see that you can do a 10 week course and know all the regs -probably takes years really to get grips with them and then the IET will change them:^O

 
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Well everyone (ME!!!) was moaning about the last scabarous pic of myself, so i thought i would show you one where i was fitter and more handsome (not to mention a little slimmer) :)
I believe that the barrow needs to be protected against overload m8.

:^O :^O:^O:O

I`m attempting to stay somewhat in keeping with the OP, as I was told off somewhat for being obtuse. :(

(Mind, I was NEVER that obtuse)

:^O :^O

 
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............Any how, what I am relating this to is the number of occasions I have seen on the old 4 way wylex boards (BS3036 fuses) where an electric shower has been installed on seperate 30 amp switch fuse but 6mm T&E has been connected into the main switch..............
Just dug out an old photo where this had been done..

it was on a PIR from a couple of years back.

my customer was buying this house.

this was the condition of the fuse box(es) :(

nice 6.0mm to main switch!

Also I was intrigued by how the fuse mounting cover was cracked.. :(

look at orange cover

and the main bar in the large box was also cracked! :_|

crack around left hand screw!

They must have been using a hammer to fix these in place! :^O :^O:^O

My customer quite sensibly got me to upgrade that lot to a nice new split load board. :D :D

 

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