3kw instantaneous water heater on a ring

[Theorysparky]

Just a thought

i have a quote to do for a garage that has 10 double sockets going in......

the customer wants a oversink water heater fitted...

i have reccommended a 2kw type so i can spur it from the ring

but because the garage will be used by one person at one time what are your thoughts about allowing a 3 kw type to be spurred ???

he is only likely to use one socket at a time although he may use others for charging tools

my thoughts are ,,,, have seperate supply which i would do in a domestic property... but this is slightly different

(erm i just think i have answered this myself but cant be bothered to delete it now ive written it !!!!!)

thoughts guys

 

[Apache]

Don't have a BGB (well I do but it's called 'Bovine Medicine' and won't help here) but thought fixed loads over a certain size needed to be on their own circuit. That would make your 2KW ok but 3KW not.

 

[Theorysparky]

I agree Patch

but the green book is not set in stone

hence my question regarding the loading of the ring cct

 

[Apache]

Unless you are very lucky you will unbalance your ring.

If its a garage then why not run a radial for the sockets and a separate circuit for the heater. I can't see it would add much to the job in either time or cost?

 

[Jono Pashley]

I would be inclined to see if they will go for a seperate circuit personally, never know what people will start plugging in once your gone

 

[Theorysparky]

If i run the radial then it will need to be 4mm ,,,,,which will require 25mm conduit

cost wise extra

 

[m4tty]

It's going to pull 12.5a at 240 so it's not a major problem spurred off the ring in reality but not to the regs. It's going to be used for all of 1 minute at a time and what's the worst that can happen. The mcb turns off lol. Your call tho as your names going on cert.

 

[Andy™]

Don't have a BGB (well I do but it's called 'Bovine Medicine' and won't help here) but thought fixed loads over a certain size needed to be on their own circuit. That would make your 2KW ok but 3KW not.

there is no regulation to say fixed loads over 2kw need their own circuit. there is a note in appendix 15 recommending it

theory - i would probably put the heater on the ring if its reasonable to do so.

 

[Theorysparky]

Andy

I think i will and advise the customer accordingly

if it was in a house then it would be different

cheers

 

[samson337]

I don't see any big problem doing it, you could bang a 2kw in and then someone comes a long in a few months and changes it for a 3kw, you just never no what going to be used or connected when your gone

 

[tom1]

is it the instant hot water type, not in excess of 15 litres storage?

and not exceding 13 amps,

like you say would not be on for long, bit like a 3kw kettle i guess

 

[SPECIAL LOCATION]

Don't have a BGB (well I do but it's called 'Bovine Medicine' and won't help here) but thought fixed loads over a certain size needed to be on their own circuit. That would make your 2KW ok but 3KW not.

The bit you are thinking of is cooking appliances, ovens & hobs...

Space heaters and immersion heaters....

Items wot is likely to be switched on for long durations !!!

But the power rating itself is not a preclusion from connecting onto a ring....

otherwise a lot of off the shelf domestic white goods & kitchen appliances could not be plugged into a ring...

Check some dishwashers, Tumble driers, Rapid boil kettles etc....

Often 2.7kW, 2.8kW or near as damit 3kW.

Try telling Mrs steam iron she needs a radial in the lounge to plug the Iron in!!!!!

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OR..

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Both 2.8KW?

Just a thoughti have a quote to do for a garage that has 10 double sockets going in......

the customer wants a oversink water heater fitted...

i have reccommended a 2kw type so i can spur it from the ring

but because the garage will be used by one person at one time what are your thoughts about allowing a 3 kw type to be spurred ???

he is only likely to use one socket at a time although he may use others for charging tools

my thoughts are ,,,, have seperate supply which i would do in a domestic property... but this is slightly different

(erm i just think i have answered this myself but cant be bothered to delete it now ive written it !!!!!)

thoughts guys

You will need to check with the manufactures instuctions..

But a short duration vented water heater...

one what only switches on the electric when the water is running is not prohibited from being supplied from a shared circuit.

and..

one that doesn't store more than 15L of water....

will probably be ok providing it is permanently connected with a double pole isolator switch.

As mentioned above cant see any more unbalancing issues than if they decided to come and do the Ironing in the garage with a 2.8kW steam iron jobbie!!!!

they aint gonna fill a bath with it or wash the car!!!!

As you say bit of common sense and diversity considerations imply that it will not be a problem.

Guinness

(cant be bothered to quote any pages as me book is over 2ft away in my bag where I keep all me regs books

and some people moan when quoting stuff!) :C

 

[Evans Electric]

I'd just do it TBH, no different to plugging in the kettle.

If you overload the circuit the trip will go.

We take on board all the regs and the OSGs and the charts and graphs and tables and in the end we become reluctant to make a decision.

If it was a 3KW heater I'd say install a radial. 3KW instantaneous is only on for about 1/2 minute.

 

[revjames]

The word instantaneous is a bit misleading. If its a Zip then you do get instantaneous boiling water BUT it is cutting in and out all the time to keep the 2L of water inside hot so not only used for 30 sec. Still I wouldnt worry about using 12A out of a total of 32A.

 

[Andy™]

but they are usually only 2kw. the heat on demand type are usually 3kw

 

[Electroglow]

I have seen 3 kw wired in 2.5 on a length of 20m on its own cct tho.

I have wired 3kw on 2.5 in the past. Your spur will on b 2.5 any way.!!

 

[Mr T]

The job I am currently on at the moment involves moving exisiting circuits from a three phase board to a new single phase board - there are wall heaters & water heaters both rated at 2KW on radials that have been wired in 2.5 and protected with a 16 amp MCB...However the job also required a new water heater which I have included on a ring final circuit so I would say include it on the ring...

 

[Electroglow]

How many 2kw heaters were on the 2.5 radial? 1 or 2??

 

[green-hornet]

As you say bit of common sense and diversity considerations imply that it will not be a problem.

Guinness

(cant be bothered to quote any pages as me book is over 2ft away in my bag where I keep all me regs books

and some people moan when quoting stuff!) :C

This is one of the best answers I have ever seen, its factual and brilliant in simplicity.

The water heater is unlikely to be used for any period of time to cause any damage to the loading, therefore as Special Locations says above, common sense and diversity considerations would allow you to safely spur off the ring.

 

[Mr T]

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