Can an inverter run off an indoor socket?

[stresshead]

Been talking to an engineer today & was told that a Daikin 3.5KW inverter air conditioner can run off a 13amp ring main socket with the correct power breaker. Is this correct as the maximum load it will pull is 6.5- 10.5 amps. Even Daikin say its possible, will run ok but not recommended as a failing unit could pull up to 16amps. Then again wouldn’t a power breaker cut off at 10-13amps?

[rbartlett]

I have seen a Daikin 71, quite a few 68's, loads of 50's, and squillions of 3.5/2/5/2.0/etc inverter(s) running off a 13a fused spur -and I have never gone to one with a blown fuse yet...

I must admit to laughing at the recent 20a c/b thread and the ratings some are coming out with.

As an example Daikin rate their in ceiling VRV ahu's at 16 a !! yes 16a for an indoor board and a 50w fan motor pulling less than one amp!!

Our last VRV the sparks was adamant that we simply could not run a ring main round for all the indoor units and each should be fed 16a separately as that is what the indoor unit marked as.
In the end I told him "just do it and I'll cover it and oh by the way change the 13a for a 6a while you're at it"

I need to get my head round Daikins logic -the unit normally pulls 4 a but they want you to run a 16a supply as 'a failing unit can pull 16a'

Personally I want my unit to switch off long before it's pulling 4x normal current.-and believe me 10a on a 3.5kW is NOT normal before you say..

Cheers

Richard

[stresshead]

I have seen a Daikin 71, quite a few 68's, loads of 50's, and squillions of 3.5/2/5/2.0/etc inverter(s) running off a 13a fused spur -and I have never gone to one with a blown fuse yet...

I must admit to laughing at the recent 20a c/b thread and the ratings some are coming out with.

As an example Daikin rate their in ceiling VRV ahu's at 16 a !! yes 16a for an indoor board and a 50w fan motor pulling less than one amp!!

Our last VRV the sparks was adamant that we simply could not run a ring main round for all the indoor units and each should be fed 16a separately as that is what the indoor unit marked as.
In the end I told him "just do it and I'll cover it and oh by the way change the 13a for a 6a while you're at it"

I need to get my head round Daikins logic -the unit normally pulls 4 a but they want you to run a 16a supply as 'a failing unit can pull 16a'

Personally I want my unit to switch off long before it's pulling 4x normal current.-and believe me 10a on a 3.5kW is NOT normal before you say..

Cheers

Richard

I had to scratch my head and wonder what the so called technical expert at Daikin was talking about. Told me at start up it would pull about 4.5amps & at max would be about 6.5amps. But they still recommended 16amp supply just incase. But with a 16A supply I’d only know I had a faulty unit either after it went bang or I got my electricity bill. Think I’ll run it off an 13A spur & save myself about £200.

[puddleboy3]

I understand it to be that the fuse rating is to protect the cable not the appliance. For instance TV's,Fridges,Hairdriers all come with a 13Amp fuse in the plug put they pull no where near that. Every appliance should be internally fused like all Daikin units, Mitsi units and so on. I think this is the way it works but ive been wrong before.

[stresshead]

Thought TV’s were 3-5amps.
I think I remember doing electronics at college many years ago & the fuse rating was always done by the maximum load the appliance would / might use. Now if Daikin & other manufactures are saying use a fuse rating up to four times the maximum input power just incase the compressor goes wrong then:
1. The internal fuse has to be 16 or more amps to allow the compressor to pull that amount for current.
2. Letting the compressor pull that sort of load if its faulty is going to do more harm then good.

[The MG Pony]

I all ways calculate my breaker circuits for 1.5% of max load, this allows for inrush nicely for fast blow fuses or use max inrush and a slow blow.

either way I want it to break the circuit if any anomaly is on there.

[puddleboy3]

Work this one out then Daikin Technical databook states MFA@15A for a RXS35CVMB but the internal fuse on the unit is 20A. Im really confused now not that it takes much to confuse me! LOL

[chilly]

16a to feed a ring main with up to 16 units and im happy, Individualy fuse an indoor with a 5 amp, If the unit blows the 5 amp fuse there is sopme thing wrong. I dont want to allow the unit to pull more than 5 amps.
I love design engineers covering their arses at the expence of the trade.

Old school.

[stresshead]

Work this one out then Daikin Technical databook states MFA@15A for a RXS35CVMB but the internal fuse on the unit is 20A. Im really confused now not that it takes much to confuse me! LOL

You've confused me as well

[daddymac]

I have just found TWO RSX60 invertors running off ONE 13a plug! I spluttered in horror, only to be told that the units had run hapilly all summer. I'm not condoning this, but the plug was only slightly warm and there were no signs of it over heating...which suggests we should take some of the specified ratings with a pinch of salt!

[mick2me]

I have just found TWO RSX60 invertors running off ONE 13a plug! I spluttered in horror, only to be told that the units had run hapilly all summer. I'm not condoning this, but the plug was only slightly warm and there were no signs of it over heating...which suggests we should take some of the specified ratings with a pinch of salt!

Dont forget that there is a difference between the closeness of protection between MCB's Cartridge fuse and open wired fuses. MCB's being the closest and Open wired fuses the other end.

PLug running hot? What the socket or the plug itself?

In the case of the 'plug top' that could be due to a poor connection on the cartridge fuse, but would probably show discoloration. Or it could be the cartridge fuse itself running close to its max load and heat being conducted from it to live pin and clips?

This would possibly lead to a 'tired' cartridge fuse failure after time, due to running close to fuse failure rating.

Breaking open a failed cartridge fuse and examining the wire ends under a high power lens reveals cause of failure. Sharp irregular end = Blow due to fault, and subsequent high current flow.
'Blobs' on ends = melt due to overload.

Myself I prefer close protection of correct rated MCB if its not too much extra work. You can get MCB's for about a fiver.

Dont forget the emergency isolator next to the outside unit however its fed 13a or MCB.

See also elswhere here about failures of RCD's due to inballance in the live and neutral sides due to current in the control wire?

[daddymac]

I'd never thought of breaking a cartridge fuse open to determine the characteristic of failure! Good idea!
Oh! For the record, I'd never condone 2 units running off a 13a plug, and I'm with you on MCB's, and certainly ext isolators!! I was just suprised that this dodgy arrangement hadn't caused a problem!

[Ian Neill]

Hi .... I'm going to fit a new Mitsubishi Heavy in my own house at the weekend....A SRK35ZD 3.5kw R410A Inverter unit It has no start current and runs at 5amps( isn't that about the same as a 32" TV or a large Fridge Freezer?) so the 13amp socket is what i'm going to use..... With 5amp fused spur at indoor and local isolator at condenser ......can't see a problem with that.

[frank]

I can't see a problem also providing the ring main isn't overloaded with your 5A.

What fuse are you going to put in your plug top?

From memory, they come in 3A, 5A, 10A, 13A.

I would go for a 10A (twice the running current) which should give you loads of protection in the event of a problem. 5A might trip.

[rbartlett]

Can a mod lock these two threads as it's just going round and round in circles and I'm losing the will to live..?

oh and those self installing please please please please for gods sake just bloody well get on with it the warranty will run out before it's installed......


cheers

Richard

[frank]

AAhh com'n Richard - the thread is only 15 posts long. Plenty of room yet for repeat answers, repetitive questioning, circular thingies, more fun etc.

Someone is bound to post yet with an interesting question like - HELP! I've got a nasty cold burn and the house electrics have just caught fire - what do I do now