Well ?? Can you.............

[Abe]

Another casual saying...............

You can run a small bedroom invertor straight off the ring main.........

Well can you???

A tech bod tells me as it is a fixed appliance , it must have its own dedicated supply..............

well??

[chemi-cool]

Hi Abe,
Yes he is right,
It should cost extra.

Chemi

[rbartlett]

depends on what you mean.

you can either fit a 13a plug and plug it in or tap off a 13a fused spur and wire it into that.

this can be done without notifying the local authority but NOT in a kitchen or bathroom -which is covered by part P

cheers

richard

[eggs]

As a general rule, anything up to 3.5kw on a fixed speed compressor can be plugged in to 13a plug, not just the inverters.
After the magic 3.5kw, the start current goes above the 32a of a ringmain.
If you look at an inverter electrical spec, for example:
10kw hitachi cassette , start current 10.5a FLC 11.5a.

Why can this not be run of the ringmain??????

cheers

eggs

[rbartlett]

As a general rule, anything up to 3.5kw on a fixed speed compressor can be plugged in to 13a plug, not just the inverters.
After the magic 3.5kw, the start current goes above the 32a of a ringmain.
If you look at an inverter electrical spec, for example:
10kw hitachi cassette , start current 10.5a FLC 11.5a.

Why can this not be run of the ringmain??????

cheers

eggs

when you say

'After the magic 3.5kw, the start current goes above the 32a of a ringmain.'

I would have thought the 13a fuse would give out before that

cheers

richard

[eggs]

you would, but it doesn't does it? maybe 13a fuses are type D , i dont know?
what we do know is that portables up to 4kw come with a plug on? they work fine, don't they.
It's not that long ago, just before the M series mitsis came out, you used to have to cut the plugs of the indoor units if you wanted to hard wire them.
Still on the Gree chinese cheapies, you get plugs fitted from the factory.

I don't know the answer, as you know i'm not a technical man, but i think i may be barking up the right tree with the "the start current doesn't last long enough to blow the fuse"

PASS ??????

cheers

eggs

[chemi-cool]

Hi guys,
If you use an ampermeter with a "peak", you will see that a 3.5 KW unit will jump up to 60A at start.
This peak is for less then a second and we use over here a 10A fuse.
It doesn't trip cause its what we call a slow fuse, after starting it draws only 4.5 amps.

Chemi

[rbartlett]

you would, but it doesn't does it? maybe 13a fuses are type D , i dont know?
what we do know is that portables up to 4kw come with a plug on? they work fine, don't they.
It's not that long ago, just before the M series mitsis came out, you used to have to cut the plugs of the indoor units if you wanted to hard wire them.
Still on the Gree chinese cheapies, you get plugs fitted from the factory.

I don't know the answer, as you know i'm not a technical man, but i think i may be barking up the right tree with the "the start current doesn't last long enough to blow the fuse"

PASS ??????

cheers

eggs

you are assuming that the 32 is a b type if a c or even d has been fitted then all bets are off..

oh and it possibly has a load already on it before the addition of the a/c


cheers

richard

[frank]

maybe 13a fuses are type D , i dont know?

A 13A plug top fuse to BS1362 will withstand 1.9 times it's rated current for 30mins before it fails. http://rswww.com/cgi-bin/bv/rswww/su...5&cacheID=ukie

Thats all right Eggs as the output rating of 4kw and a COP of , say, 3:1 means that the input rating is ony 1.33kw.

start current 10.5a FLC 11.5a.

This could only happen with an inverter drive compressor. Normally, start current is 5.8 times the running current (unless you are talking 2 pole motors or large industrial motors.

I didn't find any technical data for Hitachi on the web http://www.hitachiaircon.com/files/a...20Brochure.pdf but I do have some in the office. As a comparison here are the Daikin specs http://www.spaceair.co.uk/cgi-bin/pa...121%20tech.pdf
See note 5 of the electrical data

[eggs]

yipee,
does this mean i can throw away the 4mm aromoured cable and just throw some 1.5 T&E to the outdoor unit now
or am i miss reading something??

cheers

eggs

Ps, hitachi recommend a 32a mcb for that 10kw inverter system

[frank]

Under 16th Edition Regs, the mains electrical cable should be selected based on the running current, not the start current.

The fuse size or MCB size is determined by the manufacturer or if that is not available, by your own calculations.

1.5mm2 twin and earth will accept 19A running current max. Depending on installation method.
4mm armoured will accept 34A running current. Depending on installation method.

Start current does not figure anywhere.