immersion heater and a shower pump

[pushrod]

An immersion heater on a plug top - not allowed as should be on a switched connection unit to BS 1363-4. What code would you give it ? and out of interest what is the thinking in not allowing it as a plug and socket would give double pole isolation?

Also would a shower pump be allowed on a plug top? Plus it is on the same circuit as the immersion. My initial thought was that the pump could be on a plug and socket but should not be on the same circuit as the immersion

cheers.

 

[MarkieSparkie]

The immersion heater is usually 3kW, greater than 13A load, so BS1363 accessories are inadequately rated, must be on a 20A BS EN 60996-1 double pole control switch,to provide isolation for maintenance. The immersion heated must be on a separate dedicated supply if the immersion tank is over 15 litres. The shower pump should not be connected by plug and socket, I would suggest ideally this needs a dedicated supply, as some shower pumps have high in-rush currents on start-up and may require a type C MCB. Depending on the rating of the pump a BS 1363-4 switch fused spur outlet or BS EN 60996-1 double pole control switch for isolation. Remember the nearest socket should be at least 3.6m away from the shower tray or 4.2m from a fixed head shower in a wet room.

 

[pushrod]

The immersion heater is usually 3kW, greater than 13A load, so BS1363 accessories are inadequately rated, must be on a 20A BS EN 60996-1 double pole control switch,to provide isolation for maintenance. The immersion heated must be on a separate dedicated supply if the immersion tank is over 15 litres. The shower pump should not be connected by plug and socket, I would suggest ideally this needs a dedicated supply, as some shower pumps have high in-rush currents on start-up and may require a type C MCB. Depending on the rating of the pump a BS 1363-4 switch fused spur outlet or BS EN 60996-1 double pole control switch for isolation. Remember the nearest socket should be at least 3.6m away from the shower tray or 4.2m from a fixed head shower in a wet room.

Thanks for the reply. GN1 specifically says immersions should be connected via switched units to bs1363-4 ie 13A FCU. (don't think if it is a typo, think it is 554.3.3, but not got brb with me to check).

3kW is 13.04A so effectively 13A.

This immersion has a resistance of 19 ohms so is drawing 12A. Still unsure as to the thinking as to why an FCU is allowed and yet a plug top that would provide perfect double pole isolation is not.

Don't know the size of the motor, suspect it is pretty small, or even what fuse is in the plug, but do know that it has been working fine for 10 years on its plug top; an fcu is, again, only 13 A though.

Code 4 for the immersion being on a plug top?

 

[malcolmsanford]

Quite a few Grundfos pumps now come with a 13amp plug top fitted, I know this as I fitted a Salamander pump in November in my daughters house. The only thing it recommended was the usual 3mm gap on the terminals which MK sockets have.

As for a type C breaker again I'm not sure I have ever seen a domestic installation or piece of equipment ask for a type C breaker. Maybe if you had welding equipment in the garage but that is all I can think of. A small shower pump will not have any more inrush than a refrigerator compressor really, as most domestic shower pumps are under 700watt.

Not sure I would code it anything really, espicially if there were no signs of burning or damage to either the socket or plug.

 

[pushrod]

Quite a few Grundfos pumps now come with a 13amp plug top fitted, I know this as I fitted a Salamander pump in November in my daughters house. The only thing it recommended was the usual 3mm gap on the terminals which MK sockets have.

As for a type C breaker again I'm not sure I have ever seen a domestic installation or piece of equipment ask for a type C breaker. Maybe if you had welding equipment in the garage but that is all I can think of. A small shower pump will not have any more inrush than a refrigerator compressor really, as most domestic shower pumps are under 700watt.

Not sure I would code it anything really, espicially if there were no signs of burning or damage to either the socket or plug.

Cheers Malcolm,
Yeah this motor was only on a 5A fuse so probs in the region of 700W.

Still intrigued as to why BS7671 says you can have a 13A fcu for the immersion but not a plug top. I had wondered if it was to do with it being fixed equipment, but a grundfos (central heating?) pump would surely be considered fixed equipment. Anyway suppose there are more important things to think about

 

[amychats]

hi all,i'm new to this and don't know if this is the best place to ask my question?i have an immersion heater,the whole house is electric.i have storage heating on e7 tariff,and want to know if i can have a timer fitted to my immersion heater to make the most of this.it is currently wired directly into the wall,no plug socket,and simply says on or off.is this an electrician or plumber job?and can it be done?also the immersion heater is not huge,and has one jacket to insulate.if i heated my water in the morning,it'd be lukewarm by the time i need to wash up and bath my kids in the evening,as this has happened before.but if i heat it an hour before i need it,its hot (although even if i use the whole tank of hot water just to myself for a hot bath it still doesnt have enough to fill up or top it up)is insulation the problem?and the fact the tank isnt huge?i take it i cant boost as i only have one pre programmed thermostat.i dont want to have to keep heating at peak tariff to get nice hot water :-( its a rented house,so cannot change this setup.please help,thanks in advance.

 

[telectrix]

hi all,i'm new to this and don't know if this is the best place to ask my question?i have an immersion heater,the whole house is electric.i have storage heating on e7 tariff,and want to know if i can have a timer fitted to my immersion heater to make the most of this.it is currently wired directly into the wall,no plug socket,and simply says on or off.is this an electrician or plumber job?and can it be done?also the immersion heater is not huge,and has one jacket to insulate.if i heated my water in the morning,it'd be lukewarm by the time i need to wash up and bath my kids in the evening,as this has happened before.but if i heat it an hour before i need it,its hot (although even if i use the whole tank of hot water just to myself for a hot bath it still doesnt have enough to fill up or top it up)is insulation the problem?and the fact the tank isnt huge?i take it i cant boost as i only have one pre programmed thermostat.i dont want to have to keep heating at peak tariff to get nice hot water :-( its a rented house,so cannot change this setup.please help,thanks in advance.

electrician's jnob to fit timer to immersion. rough guess if no snags would be around £60-£80

 

[telectrix]

as regards pump being on same circuit as immersion. regs. say no, but nothing in the regs says you can't have a 3kw electric fire and another load on a 16A radial.

 

[pushrod]

as regards pump being on same circuit as immersion. regs. say no, but nothing in the regs says you can't have a 3kw electric fire and another load on a 16A radial.

Yep, that is what i thought - not exactly an example of joined up thinking

Regs say immersion can be on double pole FCU with a 13A fuse, but not on a plug top with a 13A fuse. Take the plug out and you have DP isolation .

Be nice if they gave the occasional reason why.

 

[amychats]

electrician's jnob to fit timer to immersion. rough guess if no snags would be around £60-£80

thanks telectrix for your fast help.any ideas to keep the water hot?or is this just the way things are for this smallish sized heater?would putting extra insulation really make alot of difference?thanks

 

[terminator]

Yep, that is what i thought - not exactly an example of joined up thinking

Regs say immersion can be on double pole FCU with a 13A fuse, but not on a plug top with a 13A fuse. Take the plug out and you have DP isolation .

Be nice if they gave the occasional reason why.

Probably because the plug can be inserted or withdrawn from an unswitched socked thereby causing arcing!

 

[pushrod]

thanks telectrix for your fast help.any ideas to keep the water hot?or is this just the way things are for this smallish sized heater?would putting extra insulation really make alot of difference?thanks

Putting extra insulation on a hot water tank will help keep the water warmer for longer but not indefinitely as heat will always escape through the various copper pipes. In my own house the hot water tank is in the cupboard with the towels so i don't mind some heat escaping as it warms them. It is very hard to keep the water vastly hotter than its surroundings. Only you can really decide if it is worth spending money to keep the water warmer for an extra hour or two.

Probably because the plug can be inserted or withdrawn from an unswitched socked thereby causing arcing!

But you can switch the socket off before the plug is withdrawn and it is very unlikely that it is going to be regularly removed anyway. Household appliances used on unswitched sockets are going to be much more of a problem in this regard.

 

[terminator]

But you can switch the socket off before the plug is withdrawn and it is very unlikely that it is going to be regularly removed anyway. Household appliances used on unswitched sockets are going to be much more of a problem in this regard.

Yeah I agree Pushrod, but I was just trying to think of their reasoning behind the ambigous regs. How many householders bother to switch off before removing plug and it's a fairly heavy load. It wouldn't take too long to burn the socket/plug if it was done regularly. I know you say that's unlikely, but expect the unexpected with the uninitiated.

 

[pushrod]

Yeah I agree Pushrod, but I was just trying to think of their reasoning behind the ambigous regs. How many householders bother to switch off before removing plug and it's a fairly heavy load. It wouldn't take too long to burn the socket/plug if it was done regularly. I know you say that's unlikely, but expect the unexpected with the uninitiated.

Maybe that is a friday afternoon reg, after they had all been to the pub

 

[malcolmsanford]

hi all,i'm new to this and don't know if this is the best place to ask my question?i have an immersion heater,the whole house is electric.i have storage heating on e7 tariff,and want to know if i can have a timer fitted to my immersion heater to make the most of this.it is currently wired directly into the wall,no plug socket,and simply says on or off.is this an electrician or plumber job?and can it be done?also the immersion heater is not huge,and has one jacket to insulate.if i heated my water in the morning,it'd be lukewarm by the time i need to wash up and bath my kids in the evening,as this has happened before.but if i heat it an hour before i need it,its hot (although even if i use the whole tank of hot water just to myself for a hot bath it still doesnt have enough to fill up or top it up)is insulation the problem?and the fact the tank isnt huge?i take it i cant boost as i only have one pre programmed thermostat.i dont want to have to keep heating at peak tariff to get nice hot water :-( its a rented house,so cannot change this setup.please help,thanks in advance.

Can't see how a timer is going to help you really. Even if you fit it and it comes on in line with your storage heaters, the circuit to the immersion heater is still going to be on connected to your normal tariff.

If you have an older E7 system it will have 2 meters and 2 fuse boards. I meter and board for your normal electrics say which the immersion is on, and another meter and board for your heaters.

If it's a modern system then it will most likley have a single meter but with 4 large cables coming out of it to either again 2 fuse boards, or a single fuse board split in normal and E7 system.

If you do decide to fit the immersion into the E7 system you have to remember that by the time you get home in the evening there will be very little hot water as it's charges up all night and remained hot during the day, slowly cooling down.

It may pay you to look at either setting up the existing system on a timer which is better for you, say coming on at 5am going off at 8am, then coming on again at 4pm and going off at 7pm

Or you can get a tank installed that as 2 elements which would utilised the E7 on one element and the other element the normal electricity.

Whatever you decide it will pay you to get an electrician in to see what is the best path for you.

 

[tonys]

An immersion heater on a plug top - not allowed as should be on a switched connection unit to BS 1363-4. What code would you give it ? and out of interest what is the thinking in not allowing it as a plug and socket would give double pole isolation?
cheers.

Where exactly does this information come from ?

 

[SimpleSimon]

Yeah I agree Pushrod, but I was just trying to think of their reasoning behind the ambigous regs. How many householders bother to switch off before removing plug and it's a fairly heavy load. It wouldn't take too long to burn the socket/plug if it was done regularly. I know you say that's unlikely, but expect the unexpected with the uninitiated.

The only reasoning I can think is with a plug and socket the householder than has the chance to put one of those double plug top and have both the immersion heater and some other big appliance on the same circuit. Possible overload.

But the reasoning goes out of the window because immersion spurs are usually located in an airing cupboard so what else you would fit in an airing cupboard I don't know.

 

[Deleted member 9648]

I suspect the reason is that most 13a plugs and sockets dont handle prolonged periods at maximum load very well. I've seen plenty of burnt out 13a sockets in airing cupboards....often with piles of clothes stacked round them.

 

[malcolmsanford]

Problem with putting a 3kw load onto a BS 1363 Socket is the load on the socket outlet not the circuit. Very few sockets today are designed to take a 3kw load on the socket and plug top, MK and Crabtree still might, but the majiority of them are rated at about 8-10amps,

A lot of people get the not allowed bit from appendix 15 where they mistake not supplying from the ring final circuit to mean a BS 1363 Socket. Because it is a large load if it was connected to a ring it might deem to unbalance it.

Though a BS 1363 socket outlet affords you on load isolation and functional switching the same as a BS 1363-4 FCU very few sockets are double pole as the FCU normally is, and you have the loading situation as I stated above.

IMO I would not connected a 3kw load with a plug and socket.

 

[andyb]

Where exactly does this information come from ?

554.3.3 Tony

 

[malcolmsanford]

Nice one Andy I clean forgot about that one but spot on.

 

[pushrod]

Where exactly does this information come from ?

Nice one Andy I clean forgot about that one but spot on.

I already quoted that (554.3.3) and GN1 (page 131) in post #3


Keep up at the back

 

[malcolmsanford]

I already quoted that (554.3.3) and GN1 (page 131) in post #3


Keep up at the back

Got to remember mate that age is selective, I neverl isten to a word you say push ....................

No fair do's mate you did, and I did forget about the old heaters immersed in water regs.

 

[pushrod]

Where exactly does this information come from ?

Got to remember mate that age is selective, I never listen to a word you say push ....................

No fair do's mate you did, and I did forget about the old heaters immersed in water regs.

Well that is you, the wife and quite a few others ....... LOL

 

[terminator]

I already quoted that (554.3.3) and GN1 (page 131) in post #3


Keep up at the back

Yes you did quote that and I missed that as well - well done pushrod. It was 1.00 in the morning (well that's my excuse)

 

[amychats]

Can't see how a timer is going to help you really. Even if you fit it and it comes on in line with your storage heaters, the circuit to the immersion heater is still going to be on connected to your normal tariff.


thanks for your help.isnt all my electric cheaper during e7 hours anyway?or just the storage heaters?

 

[tonys]

I already quoted that (554.3.3) and GN1 (page 131) in post #3


Keep up at the back

Under the 16th I was pulled by the NICEIC for coding a "plug top immersion domestic one" wanted to know whether it was different under the 17th so I need to look a bit closer into this one for the future.

Cheers Tony

 

[tonys]

Just looked a bit deeper into this, and domestic type immersion heaters are of an insulated type not an uninsulated type.

Therefore Regulation 554.3.3 does not apply to the type I'm referring too, the ones that are fitted into cylinders in domestic situations.

That's why the NICEIC put me in my place a about 4 years ago when I was carrying out PIR's under the 16th Edition and nothing as changed in the 17th Edition to my knowledge.

So a plug top is acceptable.

Cheers Tony

 

[Martin Bradley]

Hi im new to this site, you are correct the Imm Heater should not be on a plug top nor should it be on a 13 amp double pole fused spur, it should be on a 20 amp doulbe pole unfused spure, the reason being is that under current regs the 13 amp double pole fused spure falls below the required protection, this is due to the current regs using the voltage range of 230V and not 240V calc this and you will come up with 2990 watts, and as you have stated the IMM heater is 3KW no diversity allowed 100%, and as for the shower pump is the plug top located out side the zones, if so then this would be ok acording to current regs, under a bath with a fixed panel screwd would also meet current regs, as this is clased as having to use a tool to gain access to under the bath, but must be fused acording to raiting of pump.
If not no cert can be issued for work, pump does not require one if out side zone on plug top. but IMM heater will.

 

[Martin Bradley]

Ps as for the IMM heater being on circuit with pump, sorry but this is a ano can do, IMM heater as Markie says if over 15liter should be on dedicated circuit.
http://www.electriciansforums.net/members/markiesparkie.html

 

[tonys]

Hi im new to this site, you are correct the Imm Heater should not be on a plug top nor should it be on a 13 amp double pole fused spur, it should be on a 20 amp doulbe pole unfused spure

So should I remove the plug top from my 3kw kettle and put the kettle on a 20 amp pole switch ? OMG

 

[telectrix]

the immersion heater is wired with a plug top for a good reason. it's so he can shove the cable to the pump in with the plug pins, saves using matches.

 

[tonys]

the immersion heater is wired with a plug top for a good reason. it's so he can shove the cable to the pump in with the plug pins, saves using matches.

OMG That's a code 3 lol

 

[telectrix]

i'll raise your code 3 to a code 2

 

[tonys]

i'll raise your code 3 to a code 2

Ive watched a mate do the plug pin trick with his train-set transformer, threw him across the room, copied his old man.

 

[Martin Bradley]

So should I remove the plug top from my 3kw kettle and put the kettle on a 20 amp pole switch ? OMG

Are you sure your kettle does not say 2800 to 3000 watt, as your kettle reaches that point of say 3000 watts, for a short spell, yes it is over the raiting of the fuse, but for a short spell, also if you was to calculate the real Voltage of the supply you would find it is over the stated amount of 230 volt in the regs, you may find it at say 242 volts and yes this would lower the current that would be drawn through the fuse and thus protecting the appliance and house from fire, but as i said before if you want to comply with the regs you must apply the regs, and yes if your kettle was to be on for an Hour constant, yes i would recomend you cut the plug off. and yes i would saythat it would e a code 2. But come on we are only on this site to make things better, and Clarification, not who has the biggest Regs book.
Crazy thinking always comes clear in the end.

 

[malcolmsanford]

Are you sure your kettle does not say 2800 to 3000 watt, as your kettle reaches that point of say 3000 watts, for a short spell, yes it is over the raiting of the fuse, but for a short spell, also if you was to calculate the real Voltage of the supply you would find it is over the stated amount of 230 volt in the regs, you may find it at say 242 volts and yes this would lower the current that would be drawn through the fuse and thus protecting the appliance and house from fire, but as i said before if you want to comply with the regs you must apply the regs, and yes if your kettle was to be on for an Hour constant, yes i would recomend you cut the plug off. and yes i would saythat it would e a code 2. But come on we are only on this site to make things better, and Clarification, not who has the biggest Regs book.
Crazy thinking always comes clear in the end.

As I missed regulation 554.3.3 already, would you mind posting the reg number about the non compatibility of a 13amp FCU please

 

[tonys]

As I missed regulation 554.3.3 already, would you mind posting the reg number about the non compatibility of a 13amp FCU please

Malc

A 13amp plug top or a 13amp switched fused spur is sufficient to protect and operate the domestic type 3kw immersion heater.

Regulation 554.3 applies to uninsulated elements, not the insulated ones found in domestic type water cylinders and kettles.

People who are not sure of the Current IEE Regulations should seriously consider joining a scheme provider and use the Technical Help Phone Lines they provide.

 

[PC Electrics]

Hi im new to this site, you are correct the Imm Heater should not be on a plug top nor should it be on a 13 amp double pole fused spur, it should be on a 20 amp doulbe pole unfused spure, the reason being is that under current regs the 13 amp double pole fused spure falls below the required protection, this is due to the current regs using the voltage range of 230V and not 240V calc this and you will come up with 2990 watts, and as you have stated the IMM heater is 3KW no diversity allowed 100%, and as for the shower pump is the plug top located out side the zones, if so then this would be ok acording to current regs, under a bath with a fixed panel screwd would also meet current regs, as this is clased as having to use a tool to gain access to under the bath, but must be fused acording to raiting of pump.
If not no cert can be issued for work, pump does not require one if out side zone on plug top. but IMM heater will.

I think you are confusing your manufacturers stated ratings.
The stated rating for an immersion is usually 3kW at 240v. this gives a current of 12.5A.
The manufacturer may state an equivalent rating at 230v, which would be 2875W.
This is for the simple reason that the resistance of the element is the same no mater what voltage you apply to it (at a given working temperature and ignoring minor variances). Reduce the voltage and you reduce the power.

It's the same with showers. Manufacturers still quote the rating at 240v, because the wattage figure is higher than at 230v and so makes the shower 'look' more powerful. And in any case we pretty much still have a 240v supply anyway - the figures are something of a fudge.

What you seem to be doing is dividing the 240v rating by 230v, which is not correct.

 

[pushrod]

As I missed regulation 554.3.3 already, would you mind posting the reg number about the non compatibility of a 13amp FCU please

Guidance note 1, page 131, says "Immersion heaters should not be connected by a plug and socket-outlet, but by a switched connection unit complying with BS 1364-4." and i am sure you know already BS 1363-4 is the specification for 13A fused connection units, switched and unswitched.

 

[telectrix]

People who are not sure of the Current IEE Regulations should seriously consider joining a scheme provider and use the Technical Help Phone Lines they provide.[/QUOTE]


or retrain as a 6 week wonder plumber

 

[tonys]

People who are not sure of the Current IEE Regulations should seriously consider joining a scheme provider and use the Technical Help Phone Lines they provide.

or retrain as a 6 week wonder plumber[/QUOTE]

Don't care where they go or what they do as long as they get well away from this industry, its giving the industry a bad name.

 

[Martin Bradley]

So when are you going to start your painters course,
All you have to do is calculate it chap. Also BS EN 60669-1 spur out let 20 amp, protected by a 16 amp circuit breaker, at db, why would you put a fused spure in line on a dedicated supply for a IMM Heater. Isolating at the db then allows for maintenance, so what you are saying im wrong in my practice, or just over protecting, if you can say 100% yes to that then, prove im wrong. or explain yourself better.

 

[pushrod]

why would you put a fused spure in line on a dedicated supply for a IMM Heater. Isolating at the db then allows for maintenance, .

A double pole, switched fcu beside the immersion allows for local isolation that is in view of the person carrying out the maintenance and allows a point to change to heat proof flex.

 

[Martin Bradley]

I under stand this, what im saying is that you would use a 20 amp db pole switch and the protective devices at the ccu would be 16 amp.
this would also give local isolation, but you would still need to isolate the circuit as you may have a loose wire in the spur.

 

[SimpleSimon]

I under stand this, what im saying is that you would use a 20 amp db pole switch and the protective devices at the ccu would be 16 amp.
this would also give local isolation, but you would still need to isolate the circuit as you may have a loose wire in the spur.

Can't really count an MCB switch as local isolation IMO unless the DB is within reaching distance of the DB.

 

[Martin Bradley]

So the 20 amp double pole switch would not give local isolation come on, of course it would, what i am saying is that the 20 amp double pole switch would not be fused but would offer local isolation, but for maintenance work the 15/16 amp protective device would give you complete isolation.

 

[tonys]

There's nothing wrong with any of the following methods with regards 3kw Insulated immersion heater elements operated via a thermostat.

20 amp double pole switch backed up by a 16amp mcb/15 amp 3036: this method as been around since I was an apprentice in 1984 and that's the way I was taught.

13amp switched fused spur: used this method many times.

13amp plug top: never used this method myself, but it was not against the 15th or 16th Edition Regs and not against the 17th as far as I'm aware.

Only other thing people can do is ring their scheme Technical Help Line if they can not agree with any of the above but make sure you mention the word Insulated

 

[andyb]

Tony

I read your earlier post regarding insulated water heaters and I am confused by the term insulated in this instance.
Obviously the element is not in contact with the water but the outer sheaving is copper which is in contact with the water. The regs define insulation as a non conductive material, now I know there is a barrier between the conducting part of the element & the outer copper sheath, but I'm not sure that I would class a domestic immersion heater as insulated. Although I'm open to discussion on this.

Also the IEE on site guide states that an immersion heater should be fed from a fused connection BS1363-4 but gives no reg number as a reference.

 

[tonys]

Andy

I'm not that technical to be honest with you mate. I'm going on what I was told by the NICEIC Engineer who pulled me on a PIR just before the 17th came into to force where I had coded a immersion heater (the domestic type) for being on a plug top. So unless someone can show me where the regulations have changed on this, I'm going to stay with what I was told.

How the terminology goes with regards to the insulated material between the inner and outer part of the element, phoning a manufacturer might verify who's right in this instance. The NICEIC don't normally get things wrong imo, but like I said if someone shows me the regulation change I'm happy to accept it.

Andy

Also, what would you say with regards to a kettle element, are they not of the same principle ?