Immersion heater. Dedicated circuit?

[gselectrical]

Evening all.

Just reading through a PIR carried out by another contractor. I have been asked to carry out the remedial work.

Item 8 states "Centeral heating spured off immersion heater switch".

I have seen this and basically there is a 13A FCU (3A fuse) next to the DP immersion heater switch feeding the boiler. Now bearing in mind a boiler is not likely to pull more than an amp, is there really an issue here? Is there a reg that says otherwise?

BTW he has coded it a 2! ?

Cheers

GS

 

[M107]

If immersion has a capacity of 15 ltrs or greater it should be on its own circuit. I've not got the regs to hand but it is in there somewhere.

As for the code I'd have gone with a 4.

 

[m4tty]

+1 I just had look but couldn't find it

 

[Evans Electric]

It would not be a problem to me TBH . I'm guessing the imm. Htr. is now a standby in case the boiler breaks down , so to me someone is fly picking .

In the great 17th edition , OSG, IEE , NICEIC inspector , Part P , BS7671 rule books it will be stated that they should be on dedicated circuits !! Well at the end of the Yellow Brick Road that takes you to that "perfect world" in the sky thats fine but this is planet Earth and millions of boilers are safely doubled up with Imm. Heaters.

I won't be losing any sleep over it TBH :|

 

[batty]

Code 2 requires improvement why immersion will take no more than 12.5 amps boiler no more than a couple of amps so even if its on a 15 amp circuit it is never going to be overloaded cannot see were people get these ideas from.

 

[gselectrical]

Cheers lads

 

[wozz]

mentioned in a appendix, so dont think you will find a reg number.

 

[PC Electrics]

There is a reg, but can't give you the number right now.

I've put loads of boilers on with the immersion. No danger of overloading a 16A radial with the half amp extra of a boiler & pump!!!

The origins of the reg were to stop immersions being put on the 'ring', once a common occurance apparently.

I shouldn't take it too literally. I might comment, but probably wouldn't even code it. It's safe, so leave it.

 

[SPECIAL LOCATION]

Your general regs re water heaters (single phase) are 554.2 & 554.3

Page 143 of Old Red!

dunno greeny...

cuz I aint put me hands in me wallet yet!!!!!! ROTFWL

Also

Appendix 8, para 8.5 page 161 of OSG.

The regs stuff specifically states they must be connected via a double pole switch and NOT a socket outlet..

The OSG stuff suggests they "Should be supplied by their own separate circuit"...

and connected via a 1363-4 switched outlet..

So no specific reg saying MUST be own circuit!

Now the reg I could see you could debate is the 314.1

division of installation & minimising inconvenience...

Personally I wouldn't put the boiler on the same circuit at the imm heat, because if the boiler circuit was faulty...

You couldn't put the imm heater on to get hot water because that is off the same circuit!!!!!

As has been said Loading wise it would not be a problem....

that is providing the boiler is by a FCU.

If they had got just a socket outlet I would consider it a No No, cuz you cannot predict what some plonker may plug into the circuit while the imm heater is on!!!

Guinness

 

[steptoe]

well,

cant personally see the problem,

you can even label up the CU to say

water heater,

cos thats what the boiler does too, except the boiler even heats up the water inside the radiators as well . !!!

 

[a1]

Scoob for Specs.

 

[Evans Electric]

well,cant personally see the problem,

you can even label up the CU to say

water heater,

cos thats what the boiler does too, except the boiler even heats up the water inside the radiators as well . !!!

Steps, I believe this is called " Thinking outside the box" or Logic or "Using yer head" Its a radial supplying two water heaters. One may pull 12A the other 3A .

 

[PC Electrics]

Code 2 though is just OTT.

 

[Sidewinder]

Could it be a cable size issue that warranted the code?

 

[PC Electrics]

There's a small estate on the south of Lutty (next to the Travelodge, other side of the river), built in the mid 70's, where they all had an immersion wired in 1.5 on a 15A 3036.

Can anyone spot the [apparent] non compliance?

Sides, snakey and the rest of the Dalton gang wait till others have had a go, please

 

[Phoenix]

immersion wired in 1.5 on a 15A 3036.Can anyone spot the [apparent] non compliance?

When you apply the 0.725 adjustment figure for semi-enclosed fuses it comes out that the cable does not have the required current carrying capacity. But unlike the other correction factors (grouping, insulation, ambient temp.) which relate to to the ability of the cable to carry the design current. The re-wreiable currention factor relates to the ability of the fuse to correctly protect a cable in overload conditions. One could successfully argue that on immersion heater circuit, there is no reason to protect against overload as it cannot occur and you only need to protect against faults.

.... Do I get a slice of cake?

 

[SPECIAL LOCATION]

When you apply the 0.725 adjustment figure for semi-enclosed fuses it comes out that the cable does not have the required current carrying capacity. But unlike the other correction factors (grouping, insulation, ambient temp.) which relate to to the ability of the cable to carry the design current. The re-wreiable currention factor relates to the ability of the fuse to correctly protect a cable in overload conditions. One could successfully argue that on immersion heater circuit, there is no reason to protect against overload as it cannot occur and you only need to protect against faults..... Do I get a slice of cake?

How about popcorn opcorn

and a mug of coffee :coffee

any good? :innocent

 

[Andy™]

When you apply the 0.725 adjustment figure for semi-enclosed fuses it comes out that the cable does not have the required current carrying capacity. But unlike the other correction factors (grouping, insulation, ambient temp.) which relate to to the ability of the cable to carry the design current. The re-wreiable currention factor relates to the ability of the fuse to correctly protect a cable in overload conditions. One could successfully argue that on immersion heater circuit, there is no reason to protect against overload as it cannot occur and you only need to protect against faults..... Do I get a slice of cake?

pretty much what i would have said

 

[ProDave]

Here's an interesting one.

I admit to once connecting an immersion heater to a switched FCU from a ring final.

That's because when first fixing, the plans showed a "boiler" in a cupboard. I don't know about the rest of you, but I know what I expect when someone tells me they are fitting a "boiler"

The job was virtually finished, all flooring laid when I went to second fix, and the "boiler" turned out to be a hot water tank with an immersion heater. Too late to run another cable (it was a loft conversion)

So I took the decision to connect the immersion heater to a switched FCU on a ring final. It was only serving 4 double sockets in the single bedroom of the loft conversion.

I learned on that job to request the make and model of any "boiler" shown on the plans, and of course to determine what fuel it burned.

I guess thinking back, a better choice might have been to split the ring and use one leg as a 16A radial for the immersion heater, and the other leg as a 16A radial for the 4 sockets, but for some reason I didn't think of that at the time.

 

[batty]

Thats the trouble with these jobs i had the same thing loft conversion ring for a few sockets in loft sep circuit for electric shower and sep circuit for lights they then tell me when showeroom was installed need a point for electric water heater because it easier to do this than try to get hot water up there so ended up putting in supply from ring not ideal but when jobs are a certain stage you don't have the option just glad i put ring in otherwise they would have been stuck.