Internal or external isolation switch for aircon

[Deleted member 112675]

Hello all.

Split aircon with an external and internal unit both needing power. It seems the external takes the power and then there is an onward (power and control) connection from the external to the internal.

My question is, is it ok to site the isolator inside close to the internal unit? That would mean if an issue occured with the outdoor unit, I would need to run inside through an external door to get to the switch. But if it is placed outdoors then the same issue occurs in reverse if the indoor unit starts smoking or something....

I'm ok either way but what would the regs say ?

 

[James]

Most units are supplied to the outdoor part, normally with an isolator adjacent

 

[snowhead]

Main supply to outside, then a second isolator at the indoor unit, just for that unit.
That applied to the hundreds I've seen and or worked on in commercial buildings.

 

[Deleted member 112675]

Main supply to outside, then a second isolator at the indoor unit, just for that unit.
That applied to the hundreds I've seen and or worked on in commercial buildings.

Thanks a lot for your reply but that would mean connecting the manufacturer supplied cable (designed to connect outdoor to indoor unit) to an indoor isolating switch. It doesn't feel like that would be the manufacturer intention ?

 

[telectrix]

then let the manufacturer pay for the fire damage.......ssssimppless.

 

[James]

I can’t understand why you would need an extra isolator for the indoor unit when the outdoor isolator will isolate both the indoor and outdoor units.

 

[UNG]

Thanks a lot for your reply but that would mean connecting the manufacturer supplied cable (designed to connect outdoor to indoor unit) to an indoor isolating switch. It doesn't feel like that would be the manufacturer intention ?

If you really need two points of isolation then you could use two isolators on the supply to the aircon one inside and one outside

 

[timhoward]

I can’t understand why you would need an extra isolator for the indoor unit when the outdoor isolator will isolate both the indoor and outdoor units.

Agreed, and if you are inside and need to isolate, presumably the MCB is inside (I means as quick solution)

 

[Deleted member 112675]

So the consensus seems to be isolator outside at a minimum. That would tally with how I think its done in the US and other countries where aircon is common.

No doubt many of the friendly and helpful electricians on this forum will be installing more and more split aircon in the UK (esp in the South) and maybe the next edition of the wiring regs will make what to do even clearer.

I'm (obvisouly) not a spark but the last time I read my copy of the 18th, I thought isolation switches were not just to be used for maintenance but to be used in an emergency. The aircon user having to run outside to turn off an indoor unit or fiddle with a CU doesn't seem great.

 

[nicebutdim]

Thanks a lot for your reply but that would mean connecting the manufacturer supplied cable (designed to connect outdoor to indoor unit) to an indoor isolating switch. It doesn't feel like that would be the manufacturer intention ?

What exactly has the manufacturer specified in their instructions?

To date, every air con installation I've been involved with has had supply to rotary isolator at external unit. This provision is made at the behest of air conditioning engineers.

 

[Deleted member 112675]

What exactly has the manufacturer specified in their instructions?

To date, every air con installation I've been involved with has had supply to rotary isolator at external unit. This provision is made at the behest of air conditioning engineers.

As you say supply to the external unit. The manufacturer supplied 4 (or 5 ) core cable then runs from the external unit through the wall and supplies power (and control) to the internal unit.

That obviously means the internal unit can't be quickly isolated should it prove necessary.

 

[nicebutdim]

As you say supply to the external unit. The manufacturer supplied 4 (or 5 ) core cable then runs from the external unit through the wall and supplies power (and control) to the internal unit.

That obviously means the internal unit can't be quickly isolated should it prove necessary.

What means of isolation have the manufacturer stipulated in their instructions?

 

[loz2754]

I'm struggling to think of why an emergency isolator may be needed...

 

[Deleted member 112675]

It implies to my laymen's eyes, it needs to be protected by a 16A RCBO of the given spec (disconnect if leak of 30mA or more in 0.1 sec or less). There is no mention of a switch so you're probably right.

Brings me on to my next question which maybe I should create another thread for but as far as I know this can be spurred off an existing 2.5mm ringmain that isn't overly used. The product spec says maximum running current 9 amps. Nowhere does it mention it needs a dedicated circuit.

Thinking about it, if the spur was a fused spur at 16A and the entire existing circuit was protected at the CU with either RCBO (rated well above 16A) or global RCD, that would satisify the requirements?

 

[nicebutdim]

I'd consider it good practice to place that load on a dedicated circuit. I'd also ask where you might expect to source a 16A 'fused spur'?

In honesty, at this point, I think the best advice that can be offered is to contract the services of an electrician.

 

[GBDamo]

Hello all.

Split aircon with an external and internal unit both needing power. It seems the external takes the power and then there is an onward (power and control) connection from the external to the internal.

My question is, is it ok to site the isolator inside close to the internal unit? That would mean if an issue occured with the outdoor unit, I would need to run inside through an external door to get to the switch. But if it is placed outdoors then the same issue occurs in reverse if the indoor unit starts smoking or something....

I'm ok either way but what would the regs say ?

Rotary isolator next to the outside unit and an FCU next to the indoor fan blower.

 

[Deleted member 112675]

In honesty, at this point, I think the best advice that can be offered is to contract the services of an electrician.

A good way to close the thread down anyway. Thanks very much to most of the people here who gave good advice.

 

[DPG]

A good way to close the thread down anyway. Thanks very much to most of the people here who gave good advice.

He raised a fair question though - which 16A fused spur would you use?

 

[Deleted member 112675]

He raised a fair question though - which 16A fused spur would you use?

Agreed. Does that mean in can't in fact be installed as a spur from an existing circuit?

On one level seems reasonable if that's what it says in the MIs. On the other, even if I do get a local fully qualified spark to do the work, it seems like a lot of money and work to route a new cable from the CU. Tens of metres through several rooms or worse have an armoured cable running outside - its a big old house.

Seems very inelegant solution when the power is right there. Its pointing to getting a different aircon unit but this is Mitsubishi which is pretty well the global brand leader.

Maybe a garage style CU would be the ideal? Still a bit overkill ?

 

[DPG]

Agreed. Does that mean in can't in fact be installed as a spur from an existing circuit?

On one level seems reasonable if that's what it says in the MIs. On the other, even if I do get a local fully qualified spark to do the work, it seems like a lot of money and work to route a new cable from the CU. Tens of metres through several rooms or worse have an armoured cable running outside - its a big old house.

Seems very inelegant solution when the power is right there. Its pointing to getting a different aircon unit but this is Mitsubishi which is pretty well the global brand leader.

Maybe a garage style CU would be the ideal? Still a bit overkill ?

Are you saying the manufacturer's instructions ask for 'a 16A fused spur' ??

 

[nicebutdim]

A good way to close the thread down anyway. Thanks very much to most of the people here who gave good advice.

I wasn't expecting to be thanked, so no disappointment on my part, but let me expand upon my thinking...

It's perfectly reasonable to explore options and try to find the best/cheapest/most elegant solution to a problem, but I found myself drawn to the number of suppositions being made about what might be okay and what the manufacturer's intentions might have been.

None one but you knew what your intentions were and none of us were in possession of very much information. Some of your suggestions may have been okay, but then again they may not.

I'm never entirely comfortable when someone wishes to extract information, while providing little in the way of detail. If I grasped the wrong end of the stick, then please accept my apologies, but a lot of people come here wishing to gain the answers they want to hear and don't heed much of the pertinent information that goes along with it.

 

[davesparks]

Brings me on to my next question which maybe I should create another thread for but as far as I know this can be spurred off an existing 2.5mm ringmain that isn't overly used. The product spec says maximum running current 9 amps.

Normally you would not supply a load such as an A/C unit from a general use socket circuit. Normally a significant fixed load such as this would be installed on it's own dedicated circuit. However depending on your specific circumstances a competent person may assess this as being acceptable.

An additional consideration these days is that a modern A/C unit has the potential to interfere with the correct operation of any RCD (electric shock protection) protecting the socket circuit which could be quite a dangerous thing.

Nowhere does it mention it needs a dedicated circuit.

It won't mention what type of circuit it needs, that is up to the competent person responsible for the electrical work to decide, after all they will be the one signing the certificate for it.

 

[Deleted member 112675]

Are you saying the manufacturer's instructions ask for 'a 16A fused spur' ??

No. The phrase used was I think a "circuit breaker". So I inferred from that the usual case would be a new dedicated circuit with a 16A mcb or rcbo.

I wasn't expecting to be thanked, so no disappointment on my part, but let me expand upon my thinking...

It's perfectly reasonable to explore options and try to find the best/cheapest/most elegant solution to a problem, but I found myself drawn to the number of suppositions being made about what might be okay and what the manufacturer's intentions might have been.

None one but you knew what your intentions were and none of us were in possession of very much information. Some of your suggestions may have been okay, but then again they may not.

I'm never entirely comfortable when someone wishes to extract information, while providing little in the way of detail. If I grasped the wrong end of the stick, then please accept my apologies, but a lot of people come here wishing to gain the answers they want to hear and don't heed much of the pertinent information that goes along with it.

Yes that's fair enough and given we don't know each other you've been as friendly as I could expect. I also understand potentially giving information out in isolation (if you'll excuse the pun), could be risky in itself. So IMO extra kudos to those who do it and no hard feelings for those that don't.

In general, I've found this forum to be a far better place for a DIYer than say gas which is arguably no more dangerous as they both can kill.

Now then, how to satisfy the requirements of a 16A protection without creating a new circuit.... )

 

[davesparks]

Now then, how to satisfy the requirements of a 16A protection without creating a new circuit.... )

The short answer is that you almost certainly can't whilst also complying with the wiring regulations.

 

[Deleted member 112675]

The short answer is that you almost certainly can't whilst also complying with the wiring regulations.

Since the maximum advertised current flowing through it is 9amps (and presumably that includes start up) wouldn't a 13amp FCU satisfy them as that is more stringent (more safe) than the one in the manufacturers instructions. Or is the bugger gonna constantly trip if I do that

 

[nicebutdim]

No. The phrase used was I think a "circuit breaker". So I inferred from that the usual case would be a new dedicated circuit with a 16A mcb or rcbo.

It wasn't

Thinking about it, if the spur was a fused spur at 16A and the entire existing circuit was protected at the CU with either RCBO (rated well above 16A) or global RCD, that would satisify the requirements?

but that's besides the point.

Rather than repeatedly fire off ideas in the hope that one might gain some measure of approval, it would have been much better to lay out the problem and ask what the best solution might be. Granted, this approach might not solicit the desired response.

After my last post I looked at your forum history and note that you avoid employing tradesmen due to previous bodges (fair enough) and make the point that "there are some people {DIYers} who really take the time to understand what is required and obtain the equipment necessary". Perhaps this is one of those occasions where it is indeed necessary to really take the time to understand what is required and not look for a quick fix that may lead to unforeseen problems. I base this comment on ideas you have mooted within this thread.

 

[Deleted member 112675]

It wasn't

For your nicebutDim benefit I double checked and yes it is the phrase used. "Circuit breaker".

Are you a qualified electrician or just someone who enjoys trolling? Asking lots of questions and providing zero help.

 

[davesparks]

Since the maximum advertised current flowing through it is 9amps (and presumably that includes start up) wouldn't a 13amp FCU satisfy them as that is more stringent (more safe) than the one in the manufacturers instructions. Or is the bugger gonna constantly trip if I do that

I wouldnt presume anything, load current data doesn't normally include any startup/inrush current.

What type and rating of protective devices are protecting the ring circuit you want to connect this to?
Has this circuit ever been inspected and tested? Is it in suitably good condition for the proposed alteration?

 

[UNG]

For your nicebutDim benefit I double checked and yes it is the phrase used. "Circuit breaker".

Are you a qualified electrician or just someone who enjoys trolling? Asking lots of questions and providing zero help.

There is no need for this attitude or response

 

[nicebutdim]

For your nicebutDim benefit I double checked and yes it is the phrase used. "Circuit breaker".

Are you a qualified electrician or just someone who enjoys trolling? Asking lots of questions and providing zero help.

Your words were quoted verbatim and can be read in post #14.

I have no interest in arguing with you, nor of providing further information.

 

[DPG]

For your nicebutDim benefit I double checked and yes it is the phrase used. "Circuit breaker".

Are you a qualified electrician or just someone who enjoys trolling? Asking lots of questions and providing zero help.

He is a well respected member who has helped many people in the past. Judging by your posts I think he made the right decision in this case.

 

[westward10]

For your nicebutDim benefit I double checked and yes it is the phrase used. "Circuit breaker".

Are you a qualified electrician or just someone who enjoys trolling? Asking lots of questions and providing zero help.

Be nice because it won't take much to ditch this thread.

 

[UNG]

Be nice because it won't take much to ditch this thread.

You may as well ditch it as the guy has shot himself in the foot with his last comment.
I don't think many if any will be helping him now

 

[DPG]

Ooh he's gone!

Extra words and stuff

 

[snowhead]

Ah, and there's was me about to ask which F gas qualified and registered installer he was going to be using and maybe he should be asking them what isolation is normally installed.

 

[nicebutdim]

I read back through some of their history and it was a series of similar threads, each looking for affirmation of a specific view. Wasn't intending to start a row, but those old threads, combined with a number of conflicting reasons for refusing to employ tradespeople, didn't sit well with me.