Omission of overload protection on a shower

[m4tty]

Hi,

Can anyone point me to the reg in the BRB or BGB when it states about fixed loads not requiring overload protection please.

Thanks

 

[Andy™]

433.1.1 IIRC, or 433.3.1? or something around there

 

[Chr!s]

Hi,Can anyone point me to the reg in the BRB or BGB when it states about fixed loads not requiring overload protection please.

Thanks

Make sure you carry out an adiabatic check.

Regarrds Chris

 

[SPECIAL LOCATION]

433.3 pg 82 green'y is the omission against overload....

But you still got to consider protection against fault current ..

and the shower manufactures instructions that normally state rating of MCB and cable size no?

:C

 

[SLIPSHOD & SLAPDASH]

I cant think of any domestic situation where you rightly could omit an overload device for a shower, unfortunately its a common occurrence. Only this week i found the office we are refurbing was fed from a Henley block off a 200A head into a 40A RCD. This had a 16mm swa buried under a lawn to the office c/unit. Others had then wedged 6mm tw& earths into the main switch feeding workshops and no further protection other than 13a plug fuses, all from a 200A main fuse.

 

[Evans Electric]

Another one of Rodney's rush jobs then ???

 

[batty]

I thought it was only things like lifts that could be left without protection?

 

[sparkytim]

This is often misunderstood

A shower is a FIXED load so cannot OVERLOAD. It can develope a FAULT so has to have FAULT protection but NOT OVERLOAD protection, the two things are not the same.

A common example used to expalin this is using a 0.5mm Flex to supply a Pendant lamp holder on a 16 A protected lighting circuit

The flex cannot OVERLOAD as the load will be limited by the maximum lamp that can be inserted so it is exempt from overlaod protection.

It is still protected be the 16 A fuse of MCB in the event of a short circuit

 

[apprentice87]

Hi all,

What would the point be in even doing this??? How you going to connect the shower feed into the CU if not to an mcb? You need fault current protection, so how would you provide for this?

Cannot see the point.....

john..

 

[Andy™]

Hi all,What would the point be in even doing this??? How you going to connect the shower feed into the CU if not to an mcb? You need fault current protection, so how would you provide for this?

Cannot see the point.....

john..

there is fault protection. thats what the MCB is for. by the nature of the load, it cannot cause an overload, so no need to protect it against that.

providing te cable can take the fault current to operate the MCB/fuse, then the cable can be rated to less than the device

you could have a 9.5kw shower wired in 6mm connected to a 50A MCB.

or you could have a 3KW water heater on a dedicated circuit wired in 2.5mm and wire it to a 32A MCB

and its not much different to a 2.5mm spur fro a 32a ring or radial.... so there is a point to all this

 

[SLIPSHOD & SLAPDASH]

Hi all,What would the point be in even doing this??? How you going to connect the shower feed into the CU if not to an mcb? You need fault current protection, so how would you provide for this?

Cannot see the point.....

john..

One example would be wiring it through an RCD only as in my example as some people dont realise RCD's dont have either fault or overload protection. Sparkytim is correct above & i did mean to write that but wrongly put overload instead of fault protection (although the manufacturers instructions would say both anyhow)

In stating that i find it hard to discriminate between say, a shower element internally shorting. I would call that overload not fault ?

 

[Technician]

Reg 433.3.3

Omission of Overload can only be considered if a

"Consequential Risk" i.e. a greater hazard will be

present if the overload was to operate.

It does not alter the fact that warning systems

should be fitted or considered.