immersion help

[jl-heating]

we have a old mem board and wanting to add a temperary immersion to the board for 3 to 4 weeks till gas is fitted to the property.

struggling to get a breaker for the board.

we only have 4 circuits in the board 2 x 6 lights, 2 x 32 cooker and ring.

the only option i have is drop into the ring/cooker

i am going for 6mm to the spur and 1.5 supply to the immersion 5 mtrs.

surface trunked.

the immersion is 230 @ 2.76 KW with a design current of 12 amp.

very rough i know, i would call for a new board and upgrade it usually.

yes or no .. ????

 

[batty]

What board is it someone may have fuse or breaker for it. Post picture. You could spur off cooker circuit for 32 amp you could use 2.5mm I personally would use 4mm although its only temporary. I take they are having a combi boiler.

Batty

 

[Andy™]

if its the type i think it is, i have a few old board c/w breakers. should be a 16A in there.

but its probably goin to be easier for you to take a 2.5 from a 32A MCB to a fused spur and then to immersion

 

[jl-heating]

plan b, 6 immersion blanks wont come out .. job stopped ... oh well !!!!

i was using 6mm to fs for protection, i know it wont over load but i have to be 100% every job is checked and double checked by the electrical supervisor and i have to be squeeky clean..

 

[Andy™]

plan b, 6 immersion blanks wont come out .. job stopped ... oh well !!!!i was using 6mm to fs for protection, i know it wont over load but i have to be 100% every job is checked and double checked by the electrical supervisor and i have to be squeeky clean..

dont think you would have any problems using 2.5. fault is by the 32A, which given the length should be good, and overload by the 13A fuse

getting 6mm into a fused spur is something id rather avoid!

 

[jl-heating]

good point andy .

 

[msb2003]

dont think you would have any problems using 2.5. fault is by the 32A, which given the length should be good, and overload by the 13A fusegetting 6mm into a fused spur is something id rather avoid!

You can't connect 2.5 TW+E to a 32A breaker for a radial circuit as the cable isn't rated that high!

 

[jl-heating]

i was going overly 4mm should do it .

Supply voltage = 230 Volts

Ib - design current = 13 Amps

Protective device type = MCB typeB

In - protective device rating = 32 Amps

Length of run of cable = 5 meters

Power factor = 1

Cable Type : General purpose PVC - Singlecore

Installation Method : Single-core or Multi-core cables Fixed on (clipped direct), or spaced < 0.3 x cable diameter from a wooden or masonary wall

method C

Ambient temp = 30

 

[Evans Electric]

I've never heard anything so complicated in my life .

Temporary supply to Imm. Htr . short piece of 2.5 from ring main MCB to spur, 2.5 from spur to heater , local DP switch then heat resist flex 1.5 to heater.

6.0 mm is OTT . Just do it .

Deke

 

[jl-heating]

hehe its only a question ..

nice to stretch the grey matter sometimes.

 

[Andy™]

You can't connect 2.5 TW+E to a 32A breaker for a radial circuit as the cable isn't rated that high!

read 7671. you can have overload protection at the end of the cable. think about it - spur on a ring main is 2.5 to a SFCU (or socket). this is no different, just your taking a feed from the MCB instead of a socket. perfectly legal, and more importantly, safe

 

[Riggy]

You can't connect 2.5 TW+E to a 32A breaker for a radial circuit as the cable isn't rated that high!

I was so nearly very rude in response this, but I've managed not to be. Yay me!Applaud Smiley

 

[the doctor]

hi jl

remember, you do not need overload protection if the load cannot overload. (an immersion heater either works or does not work)

soooo, in theory you could wire the circuit in 2.5 or even 1.5 to cover the load and stick it on a 63A mcb!

the only thing you must then comply with is that the Zs for your circuit is inside the maximum for that 63A mcb!Applaud Smiley

it is an often done way of installing in europe though we tend to cringe a little!

pulling my hard hat on as i hit the send button:coat

 

[Andy™]

soooo, in theory you could wire the circuit in 2.5 or even 1.5 to cover the load and stick it on a 63A mcb!

the only thing you must then comply with is that the Zs for your circuit is inside the maximum for that 63A mcb!Applaud Smiley

and if the earth melts before breakers trips...

 

[jl-heating]

i would still rather protect the cable used to the circuit in question. all bases are covered then .. but thanks for the info doc i will have to look into variations possible.

 

[the doctor]

hey andy c

it either complies or it doesn't. and it does;\ (subject to maximum Zs)

the earth melting bit is a different issue altogether which is addressed in chapter 54.

taking it to the next level you could ( subject to volt drop, etc) wire the immersion in 1.0mm (clipped direct) which having a cpc the same size as the line conductor would not be liable to the "earth melting" equation ROTFWL

 

[Adrian]

I cant remember where I saw it in the 16th but it said something on the lines of If a water heater has a capacity of more than 10 litres it must be feed from its own independent circuit

 

[Andy™]

I cant remember where I saw it in the 16th but it said something on the lines of If a water heater has a capacity of more than 10 litres it must be feed from its own independent circuit

it should be, but like every other regulation, you dont have to do what it says, providing its safe

 

[Evans Electric]

I cant remember where I saw it in the 16th but it said something on the lines of If a water heater has a capacity of more than 10 litres it must be feed from its own independent circuit

Yes , normally you wouldn't connect an immersion htr. to the ring but this was a temporary , I believe , while the C/heating was installed.