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' ??