Domestic Instalaltions 3.5kW from 13A socket

[segar]

Hi, there,

I have been adviced by the supplier ( no names) that up to 3,5 kW Inverter is possible to connect to the 13 A socket, which was a preffered option in the house, where mains board was some two floors below in the basement kitchen and the house was recently decorated.

The clients was advised and acccepted the completed job, system is working fine too ( although she is saying this LG Inverter is far too noisy) electrician now is keen to advice her, so that she wants us to pay her back £550.00 for his job.

I have Part P electrician, whom we subcontract large jobs and whom we would have used shold the client have gone straight away for a MUlti-split system to service her other 4 rooms. My electrican is keen to put things the way she wants, however, she doesn hot want us to be involved anymore, thinking I am kind of a micky mouse company, which is frustrating.

ANy advice whould be appreciated, especially from someone who was in a similar situation

[Argus]

Most inverters about that size will be within the electrical capacity rating of a 13 amp socket.

But you didn’t tell us what the problem is that makes the client wants their money back.

.

[Karl Hofmann]

I regularly put a 13 amp plug on little inverters, the units that I install at 3.5Kw are have a 5 amp fuse in the plug and they do not cause electrical noise or sudden surges to other equipment either.

In order to demonstrate how quiet the units that I supply are, I have a little 2.5Kw inverter mounted on a frame that I carry round in the van so that the customer does not get any nasty surprises. In 99% of cases the customer comments on how quiet they are.

[Andy W]

LG, it says it all, I have always found them noisy, still not sure what the customers problem is though.

[The Viking]

Hang on, STOP!

The answer is NO, no fixed appliances or equipment can be fitted to a 13A socket (and still follow current UK guidelines).

If the equipment is permanently fixed then so does the power supply have to be, regardless of the current draw.

(Also, there need to be means of isolation within arm's reach. For us that will mean a Isolator at the outdoor unit and a switched spur at the indoor unit)

[Karl Hofmann]

Hang on, STOP!

The answer is NO, no fixed appliances or equipment can be fitted to a 13A socket (and still follow current UK guidelines).

If the equipment is permanently fixed then so does the power supply have to be, regardless of the current draw.

(Also, there need to be means of isolation within arm's reach. For us that will mean a Isolator at the outdoor unit and a switched spur at the indoor unit)

I can't find anything in the 16 wiring regs that says a plug cannot be used. As long as it is a fused means of isolation then I take it as good, though I am open to learn if I am wrong.

[Andy W]

If there is a reg stating that a plug can not be used do you have the reg number please?

[LRAC]

Domestic air conditioning is not classed as a fixed appliance, it can be removed and as such is not classed as a fixed electrical item. i am concerned that the unit is not running off a switch fused spur.

Lrac

[airconadam]

ihave recently got a 4.2 kw unit to install in a bedroom of a friend and iam goin to take it of the ring main but with a spur of a 20amp fuse on iknow other engineers which have done this and its fine with an inverter as on your main board its normally a 32amp anyway

adam

[Makeit go Right]

A 3.5kW unit draws about 6-7 Amps, which is a lot less than a 3kw kettle, drawing 12.5Amps.

There are inverters and non-inverters (and different manufacturers too). Of course a non-inverter needs a thump to get it going and that pull of current can have an impact on other electrical equipment on the same circuit. So, inverters are the better choice in a home.

If connecting to the ring main (sometime we do - sometimes not), we run a spur off of the circuit, taken from the back of a socket. The power line runs to the indoor unit (in mini trunking) with a double-pole fused switch by the unit.

Electrically that is fine AIUI. Perhaps the doubters could give us the full chapter/verse from the IEE Regs showing why not.

Not sure what is meant by 'noise' and electricians getting involved - presumably the noise referred to is not a sound thing but an electrical interference thing, which is where the electrician has entered the picture.

I suspect that your 'electrical noise' has nothing to do with connecting an inverter into the power ring but more to do with some electrical interference generated by the LG equipment. Maybe the electrician has offered some kind of electrical suppression to solve all of this for the customer?? And quoted £550 to install the suppression equipment. (Should have put that quote via you - not directly to your customer.)

I must say, the electrican (one of your sub-contractors, yes?) should have been in contact with you about he situation and his solution, before going directly to the customer. Very naughty.

I would want some good answers from him about what he has been doing and, if you have not yet paid him, I would be giving him a hard time about causing the loss of your future maintenance contract(s).

[frank]

If you look in the maufacturers recommended guide for power supplies for their kit (Daikin) and others,(2.5 & 3.5kw) you will see that they recommend a single phase, 240v 16A supply.

This cannot be achieved from a ring main or spur from a ring main

[airconadam]

but you have got a 32a fuse on your board and if you only need 16a whats the prob iknow iam young and alot to learn but it works and never had any probs with this thanks alot guys

adam

[Abe]

Personally every system of mine, 3.5Kw and above I connect to a 16 amp breaker directly off the board.

I get a qualified electrician to provide the power up to the isolator.

[frank]

I get a qualified electrician to provide the power up to the isolator.

Good on you Abe - let the professionals do the job properly in accordance with Part P and BS7671.

[frank]

but you have got a 32a fuse on your board and if you only need 16a whats the prob iknow iam young and alot to learn but it works and never had any probs with this thanks alot guys

adam

Adam

The maximum size fused spur you can take off a ring main is 13Amps.

[Brian_UK]

Also Adam, you must remember that the fuse is protecting the cable and not the equipment.

And yes, as Obi once said, "You are young my boy but......" and so on

[nevgee]

As MAKITGO right says .... Socket or fused spur switch: they both provide means of isolation and protection (13A fuse)
My understanding of the 16th is just so.

[nevgee]

If connecting to the ring main (sometime we do - sometimes not), we run a spur off of the circuit, taken from the back of a socket. The power line runs to the indoor unit (in mini trunking) with a double-pole fused switch by the unit.

Electrically that is fine AIUI.

What is AIUI?

The electrical supply to the AC unit is fed by a wire .... simple enough.
The wire used must be protected by a fuse or similar devise.
If the devise is rated (nominaly) at 32A then the wire must be capable of carrying 32A ...
Are you happy this is the case? I wonder!

You must be aware of the real implications of providing electrical protection. Electrical fires are not good for your public liability insurance premiums.

[Makeit go Right]

Sorry for abbreviation...."AIUI" means "As I understand it."

So, does anyone have the particular IEE Reg that says this is incorrect.

I must say that we have had several qualified electricians installing such spur lines, without any disagreement or even surprise, and it has all been duly certfied.

[Note, we wired into the back of the socket so that spur was genuinely off the ring and not spur off a spur etc.
ALSO, some others have spoken about using a 3-pin plug, pushed into a 13Amp socket -- that is something else and it is not something with which we would agree.]

[airconadam]

hi nevgee thats what i ment by taking it of the back of a socket and then putting a bigger fuse in a spur or an islotor etc etc

adam thanks

[Slim R410a]

If you look in the maufacturers recommended guide for power supplies for their kit (Daikin) and others,(2.5 & 3.5kw) you will see that they recommend a single phase, 240v 16A supply.

This cannot be achieved from a ring main or spur from a ring main

Frank all the 20, 25 and 35 Daikins are now rated at a 10A mcb. (bar the hi-spec ux1 15A) 50s and 60s still 20A. Whether they have done this because ppl are running off 13A to make them use a 10A fuse in the plug/spur I cant see them changing anything on the kit, still have a 20A fuse on the outdoor pcb.
We havn't run off a ring main for a long time now, always off the dist.board, most domestic jobs end up with a board upgrade too.

[Contactor]

You can run a spur off the back of a socket as long as there is only one (spur) and it is protected by a 13 amp fuse. Therefore you can run any equipment up to 13 amps off it. However this may cause the MCB / Fuse to pop depending what else is on the circuit.

[sinewave]

If the devise is rated (nominaly) at 32A then the wire must be capable of carrying 32A ...
Are you happy this is the case? I wonder!

You must be aware of the real implications of providing electrical protection. Electrical fires are not good for your public liability insurance premiums.

Not so!

Diversity, amongst othet things are used in most electrical designs.


2.5mm T/E (As used in most domestic Ring Final Circuits) is rated at 27 amps, yet is fused at 32 amps.


There is nothing electricaly wrong with running any Inverter A/C unit off a 13A plug if the running current is less than this.


FYI As well as being an Air-conditioning Engineer, I'm also a qualified Sparks with C&G 2381 & 2391 (16th Ed and Testing & Inspection)

Also have a HNC in Electrical Engineering!

[frank]

2.5mm T/E (As used in most domestic Ring Final Circuits) is rated at 27 amps, yet is fused at 32 amps.

There is nothing electricaly wrong with running any Inverter A/C unit off a 13A plug if the running current is less than this.

All new ring mains are now installed in 4mm not 2.5mm.
The reason that the 2.5 T & E, rated as you say at 27A, was fused at 32A was because the electrical current could go each way down the ring main therefore sharing the current carrying capacity.

The 27A rating can be seriously downgraded though dependant upon installation method, length of cable, insulation (i.e. covered with lagging in roof spaces etc) and other factors detailed in the regs.

The cable must be rated in excess of the fuse which must be rated in excess of the load.

I agree that you can plug a small inverter unit into a ring main if the running current is less than 13A but you must take into consideration the manufacturers recommendations and also ensure that the ring main will not be overloaded. (AC on, Washer/Drier on, etc etc.)

C&G 2381 & 2391 (16th Ed and Testing & Inspection)

Does this make you a qualified spark?? If so, then I am also a qualified spark

Contactor

You can run a spur off the back of a socket as long as there is only one (spur) and it is protected by a 13 amp fuse. Therefore you can run any equipment up to 13 amps off it. However this may cause the MCB / Fuse to pop depending what else is on the circuit.

It's not good practice to design an installation that will 'pop' the mcb. Better to have a dedicated circuit.

[hendrag]

from the threads it appears to be an Lg unit, im the tech manager for LG UK so here goes

point 1 is you cant wire the unit to a 13 Amp plug its illegal as the unit is a fixed installation. If it was a mobile unit it would be fine.This unit will only draw a few Amps and of course will run but you cant leave it like that. Who told you to wire it like this if its one of our suppliers i will crucify them, if you dont want to name and shame them here please send me an email.

point 2 is the noise, LG inverter 3.5 kW units are almost silent in operation, despite what is said above, if its making a noise there is something wrong. can you describe the noise? and give us a call this is NOT normal, i would like to send an enginner to site to witness this call to arrange.

(Phone number deleted by the moderator. Please use the PM facility)

good luck

[nevgee]

2.5mm T/E (As used in most domestic Ring Final Circuits) is rated at 27 amps, yet is fused at 32 amps.


There is nothing electricaly wrong with running any Inverter A/C unit off a 13A plug if the running current is less than this.


FYI As well as being an Air-conditioning Engineer, I'm also a qualified Sparks with C&G 2381 & 2391 (16th Ed and Testing & Inspection)

Also have a HNC in Electrical Engineering!

2.5mm cable flat PVC 70 C is rated at 27A for reference method 1 (clipped direct) but if reference method 3 is used (in trunking on wall ) then the corrected value is probably 23A notwithstanding all the other correction factors to be concidered. Further to this we must remember that it's a ring circuit so therefor the total of the cuircuit capacity is going to be much higher than the single 2.5mm wire, hence a 32A protective fuse or mcb. This fuse rating has of course a massive safety factor already built in

I hold agreement with you on the inverter application to a 13A fuse ... they work just fine even though rated at 16A.


Cheers

[malcoa]

to plug the unit in is probably not the best practice, your client is perhaps at risk from a crack off the capacitor if the unit is unplugged, a fused spur can also provide a 13A supply which eleiminates such risk, but if the installation instructions recomend a greater supply then its for a good reason and a supply direct from the consumer unit would be the only other option, a ring main is only intended to provide 13A at any outlet.
Thanks

[S_Line]

I'm very surprised no one has mentioned the Problems With RCDS and inverters on ring mains ?

A Inverter sometimes send a live to the earth causing the main RCD to trip on the fuse board.

We had loads of problems with the early Daikin inverters with this problem.
The only solution was to install a Split Load board.

[andyh]

Can someone clear this for me?

On a domestic install eg: ac in conservatory. If an air con company install an a/c split system and they employ a part p qualified electrician to install a supply from the distribution board to the a/c system. Should that electrician then continue to complete the wiring and test it from indoor to outdoor and any further wiring such as a switched pump?

As usually the air con engineer would perform the latter?

many thanks ah

[sinewave]

The 'Electrician' should test to the DP Isolator and record his/her results to this point.

It's the Air-con guys responsibility to ensure that all the electrical wiring from this point on is tested and complies.

[Makeit go Right]

On a domestic install if an aircon company install an a/c split system and they employ a part p qualified electrician to install a supply from the distribution board to the a/c system. Should that electrician then continue to complete the wiring and test it from indoor to outdoor and any further wiring such as a switched pump? As usually the air con engineer would perform the latter? -ah

{This really deserves a new thread, I think.}

It really depends on what you ask the electrician to price for. Normally, the electrical is asked to quote for/install a power supply to either the indoor unit, or the outdoor unit, terminating with an isolator, and that’s what he does. The aircon chap connects it to his Room Unit, or Condenser, and gets on with his commissioning.

Seems okay, doesn't it?.

However, you are highlighting something that is mostly swept under the carpet, which is, the interconnecting wiring (and pump wiring): The aircon chap will refer to this wiring as “controls wiring”, so that he can happily neglect any Part-P problems. But, most of the time, the interconnecting wiring includes a run of power to the other end of the split system, and then there is the pump that sometimes appears on the scene. All of that 240v should be tested, as far as I understand things.

The thing to do is get the electrician to turn up after the interconnecting has been installed, and ask him to test that also, while on site. If he is client-friendly type, he will just do it; if not, he will want some extra payment. Some will also refuse and say they did not install it so they will not test it (don't use them again!)

From the customer/regs viewpoint, the whole install needs to conform and be certified where necessary.

[R1976]

I was just reading this post and thought I would give some input.

A few weeks back I wired a Mitsubishi Electric inverter split system into a ring main as a tempory measure.

The shop was running a radio on the ring main and when the ac switched on and ran the radio made a buzzing sound like a transformer.

Maybe the inverter gave interference to the equipment.

[AbsoluteWDJ]

(Also, there need to be means of isolation within arm's reach. For us that will mean a Isolator at the outdoor unit and a switched spur at the indoor unit)[/quote]

I've had this discussion with other engineers. The mains supply has to have an isolation point. What I've found open to discussion is if the outdoor unit is main supply and has isolation then does the indoor unit require an isolator within arms length even though these can look unsightly in a domestic application? With this in mind, bathroom extract fans are switched exterior and are usually not within arms reach. Is there actual regulations stating that there has to be a switch indoor within arms length?

[AbsoluteWDJ]

You can run a spur off the back of a socket as long as there is only one (spur) and it is protected by a 13 amp fuse. Therefore you can run any equipment up to 13 amps off it. However this may cause the MCB / Fuse to pop depending what else is on the circuit.

This has to be in 4mm cable from ring main to fused spur

[Contactor]

A ring final circuit, such as a load of sockets, would typically be in 2.5mm and the feed from the spur would only need to be rated at 13 ampere. This all depends on the various rating factors of course, but even so 4mm seems a bit over the top.

A ring main is something else, usually found under the pavement.

There must be local means of isolation for outdoor, indoor and pump. Fused spur is ok.

If your tight like me you could run a ring final for a load of cassettes on a vrf in 1mm flat twin and earth.

[brunstar]

any final sub circuits must be fully tested before commissioning, this muct be carried out by the electrician.

[Makeit go Right]

any final sub circuits must be fully tested before commissioning, this must be carried out by the electrician.

(IANAE) This is an important point, when feeding a spur off the back of a socket to serve your small aircon unit. An engineer was explaining to me a couple of weeks ago how he had done this practical and safe type of spur feed to a Room Unit (power to indoor), and when customer asked for an electrical test certificate his sparkie told him he would have to test the whole ring main. It was cheaper to run a new feed to the aircon from the Consumer Unit and just test that line, than test the rather involved ring main.

Any 17th Edition sparkies able to comment?

[brunstar]

(IANAE) This is an important point, when feeding a spur off the back of a socket to serve your small aircon unit. An engineer was explaining to me a couple of weeks ago how he had done this practical and safe type of spur feed to a Room Unit (power to indoor), and when customer asked for an electrical test certificate his sparkie told him he would have to test the whole ring main. It was cheaper to run a new feed to the aircon from the Consumer Unit and just test that line, than test the rather involved ring main.

Any 17th Edition sparkies able to comment?

I can't see it being more expensive to test the circuit when all that needs to be done is all loads disconnected from the ring main and an insulation test to be carried out on the cable with a megga of 500volts or 1000volts depending on the circuit and a resistance check and fault loop impedance on the cables and circuits.
i can't see it being cheaper to run a seperate final sub circuit.

[frank]

Under 17th edition, it's not just a case of installing a new circuit and testing it. For a start, you have to consider the existing earthing arrangements to the gas and water as well.
If you install a new circuit, you are responsible for testing the whole installation, not just the new circuit.

Then there is the new RCD regs to be considered.

[eggs]

I can't see it being more expensive to test the circuit when all that needs to be done is all loads disconnected from the ring main and an insulation test to be carried out on the cable with a megga of 500volts or 1000volts depending on the circuit and a resistance check and fault loop impedance on the cables and circuits.
i can't see it being cheaper to run a seperate final sub circuit.

If only it was as straight forward.

If, when testing the existing ring an existing fault rears it's ugly head, you are duty bound to find and repair the gremlin before you can certify your own work.
Let me tell you 8 hours pulling up carpets and floor boards looking for a dodgy neutral that some kitchen fitter caused running a spur of a spur twenty years ago, cost you more than off loading the job to a sparky in the first place.

Eggs

[AbsoluteWDJ]

A ring final circuit, such as a load of sockets, would typically be in 2.5mm and the feed from the spur would only need to be rated at 13 ampere. This all depends on the various rating factors of course, but even so 4mm seems a bit over the top.

A ring main is something else, usually found under the pavement.

There must be local means of isolation for outdoor, indoor and pump. Fused spur is ok.

If your tight like me you could run a ring final for a load of cassettes on a vrf in 1mm flat twin and earth.

What I remember from my part p course (few years ago now) was that you can come off a ring main circuit but it then becomes a radial circuit and if the fuse is 32amp rated then regulation states 4mm for 32 radial. Once this 4mm is installed into 13amp fused spur the load side can then be 1.5mm.

[brunstar]

If only it was as straight forward.

If, when testing the existing ring an existing fault rears it's ugly head, you are duty bound to find and repair the gremlin before you can certify your own work.
Let me tell you 8 hours pulling up carpets and floor boards looking for a dodgy neutral that some kitchen fitter caused running a spur of a spur twenty years ago, cost you more than off loading the job to a sparky in the first place.

Eggs

don't agree with you mate, i am sorry, if a fault is evident on a circuit that is a variation to your initial quotation, as an electrician you have a responsibility to condem a circuit and make good of it at the customers expense.
I am sure if you were the last one to work on the property you would not want to be responsible for the property burning down...
If is broken then we must fix it!!

[eggs]

don't agree with you mate, i am sorry, if a fault is evident on a circuit that is a variation to your initial quotation, as an electrician you have a responsibility to condem a circuit and make good of it at the customers expense.
I am sure if you were the last one to work on the property you would not want to be responsible for the property burning down...
If is broken then we must fix it!!

is that not what i said Mate

Eggs

[paceinternet]

as an electrician you have a responsibility to condem a circuit and make good of it at the customers expense.

You would be required to obtain the customers agreement before carrying out any additional work.
In this example, you should disconnect your spur, retest and demonstrate to the customer the fault in the wiring.

[sparky james]

{This really deserves a new thread, I think.}

It really depends on what you ask the electrician to price for. Normally, the electrical is asked to quote for/install a power supply to either the indoor unit, or the outdoor unit, terminating with an isolator, and that’s what he does. The aircon chap connects it to his Room Unit, or Condenser, and gets on with his commissioning.

Seems okay, doesn't it?.

However, you are highlighting something that is mostly swept under the carpet, which is, the interconnecting wiring (and pump wiring): The aircon chap will refer to this wiring as “controls wiring”, so that he can happily neglect any Part-P problems. But, most of the time, the interconnecting wiring includes a run of power to the other end of the split system, and then there is the pump that sometimes appears on the scene. All of that 240v should be tested, as far as I understand things.

The thing to do is get the electrician to turn up after the interconnecting has been installed, and ask him to test that also, while on site. If he is client-friendly type, he will just do it; if not, he will want some extra payment. Some will also refuse and say they did not install it so they will not test it (don't use them again!)

From the customer/regs viewpoint, the whole install needs to conform and be certified where necessary.

Tell me why you should expect an electrician to test and certify a third parties work. The whole point is to sign off your own work as being safe and installed correctly and under part P being responsible for it for 3 years.

So if you asked me to sign off your work I would refuse and not work for you again as Im not into fraud.

[Makeit go Right]

Hi, James.

I am sure you understand why this would be wanted; it seems to be just a matter of whether it would be illegal for an electrician to test and certify as sound an installation already in the building, or if it is just an electrician refusing the request for other reasons.

If there is a concern about taking on a 3-year responsibility that one does not need to take on, well, the positive approach would be for the electrician to say “yes, I can do it but it will cost this much” and explain why. I don’t see where the fraud can come into it though, providing he does proper and standard testing.

For the annual testing an electrician does for most customers, the wiring is most always installed by prior electricians, and there seems to be no problem there. Maybe that is different testing(?) A proper test should find any issues with the installation and this kind of thing should be just normal electrician’s work. And I was not saying/impliying that the electrician would simply sign it off without a proper adequate testing activity.

But, you being a qualified Part-P electrician, will know a lot more about this, in which case it would be great to have the concrete data on these boards so we are all nice and legal. Could you offer some regulation paragraphs in support of what you are saying so we can read and understand the stable data on this, please.

Bear in mind, I’m not arguing with you, James. You are the qualified electrician and I am not. I am hoping you might quote the regulation paragraphs rather than just saying it is not legal/fraud.

Cheers.

[Makeit go Right]

Also, James, another thing that does not seem to add up here is this: On a domestic electrical installation (eg Loft Conversion) put in by a DIYer, the council calls in an electrician to check it over and test it all. The sparkie tests and gives it a P-cert, and then the Council gives it all a pass. How does that work?

Surely the council inspector is not committing fraud in that case? I must say I am looking forward to reading those regulation paragraphs if you'd be good enough to post them for me. It would clear some confusion I have on this.

Cheers.

[sparky james]

The Issue is that under my DIS scheme rules inspecting testing and notifying a third parties work is fraudulant.

Remember installation work must be recorded on an installation certificate which should be issued by the installer but not necessarly completed by them and existing installations are inspected and tested and recorded on a Periodic inspection report. The point is one is a certificate and one is a report.

If you have a look at the NICEIC rules of enrolment.
Its the DIS schemes rules not the Regs.
The idea is to be able to self certify your own work. The local council are there to certify others work with or without the help of their appointed contractors.

Look it up.

[sinewave]

NICEIC rules for their schemes are not legal mandatory regulations.

The 'Nicey' are renound for making stuff up to suit them and their pockets.




Look it up!


The ODPM website is where the true law is written.

[sparky james]

Only one of the part p providers allowes the inspection of other peoples work.

I think anyone signing off others works is foolish and asking for trouble if their certification body dont allow it.

What next fitting gas boilers between jobs.

Go on the 5 day course and do the job properly.