PDA

View Full Version : swa cable 1mm amps?







cadwaladr
21-05-2012, 09:46 PM
what amps can this take its swa 3 core 1mm,i want to run a 2hp single phase hermetic compressor /condensing unit there is an evap with heaters but they will not come on while compressor is running its just that this cable is already in place and is 10 metres in length from supply to unit the condensing unit .

install monkey
21-05-2012, 10:05 PM
generally 1.5mm for upto 10amp
2.5mm for upto 20amp
but as with everything theres limitations on length,voltage drop.
look at the locked or lra or fuse rating then size the cable accordingly-also a spark should fit and test a new circuit.
relaplace the cable and check the glands are suitable for the bigger cable

Yuri B.
22-05-2012, 07:37 PM
1 mm diameter or the cross-section ?

install monkey
22-05-2012, 07:39 PM
uk wiring is sized by cross section hence the mm2 after the size:o

Yuri B.
23-05-2012, 06:30 PM
Then, possible with the 1.5 kW compressor:).

install monkey
23-05-2012, 09:00 PM
always better to over compensate-a running compressor of 1.5kw will pull around 6amps- locked rotor current if non inverter should be around 20amp- until the klixon or overload or circuit breaker trips- then the cable would be overloaded-so best replace it for 2.5mmsq- then youll have a bigger earth conductor too

monkey spanners
23-05-2012, 11:30 PM
Its about 8amps a hp plus fan so 17.5a maybe, i'd probable run a bit of 2.5mm or 4mm, probably 4mm if its doing the defrost heaters etc to, just incase the relay stuck and it all tried running at once.

install monkey
23-05-2012, 11:32 PM
not influenced by the heffers (cows) chewing the cable? haha

Its about 8amps a hp plus fan so 17.5a maybe, i'd probable run a bit of 2.5mm or 4mm, probably 4mm if its doing the defrost heaters etc to, just incase the relay stuck and it all tried running at once.

r.bartlett
24-05-2012, 06:02 AM
Its about 8amps a hp plus fan so 17.5a maybe, i'd probable run a bit of 2.5mm or 4mm, probably 4mm if its doing the defrost heaters etc to, just incase the relay stuck and it all tried running at once.

A kilowatt is less than a hp and it's about 4.5a per kilowatt...

Besides a cable is rated by the fuse size not the load. Therefore a 1mm cable should have a max fuse rating of 6a.(local conditions apply) This is unlikely to be sufficient for the starting current

monkey spanners
24-05-2012, 09:21 AM
Just checked Nrs book, malrx20x unit max run amps is 17.4A, this is nominal 2hp unit. But a apcr0200 unit is 12.8A mra, seem Hp is not the best way to size a cable and it's protective fuse.

mikeref
24-05-2012, 11:44 AM
A 1.5mm at 240 volts is speaker cable. I'd give it up to 7 amps only.
If you run 4mm over that length, i would call that safe...
Electrical specs are known to be a little under-rated at times.
Best to be safe than sorry.;)

r.bartlett
24-05-2012, 12:48 PM
Just checked Nrs book, malrx20x unit max run amps is 17.4A, this is nominal 2hp unit. But a apcr0200 unit is 12.8A mra, seem Hp is not the best way to size a cable and it's protective fuse.

Nor is it best to believe the manufacturers either. Daikin rate their VRV fan coils at 15a fuse when a 3a is more than enough...

r.bartlett
24-05-2012, 12:53 PM
A 1.5mm at 240 volts is speaker cable. I'd give it up to 7 amps only.
If you run 4mm over that length, i would call that safe...
Electrical specs are known to be a little under-rated at times.
Best to be safe than sorry.;)

I think you're over cautious 3 core 1.5 can take up to 26a.

http://www.alertelectrical.com/prod/137/3-core-swa-6943x-armoured-cable

cadwaladr
25-05-2012, 01:45 AM
I think you're over cautious 3 core 1.5 can take up to 26a.

http://www.alertelectrical.com/prod/137/3-core-swa-6943x-armoured-cable i replaced it with 2.5 the running current was 6/7 amps on cooling and this was during pull down from 20 degrees c but i will ring my electrical wholesaler and enquire about the 1mm seem to remember one of my customers installing some electrical kit and what he was told about cable size of swa and the amps it could take surprised me the length/run is important in the equation i know,as this job was on a farm and we all know what the issues that pop up increasing the size was a safe bet.

goshen
25-05-2012, 07:26 AM
Hi
most regulations at least europian,allow use of cabels less than 2.5mm only for control purpose!
motors are minimum 2.5 mm!
its simply not worth the nusiance when the cable burns or over heats !
good luck

r.bartlett
25-05-2012, 07:33 AM
Hi
most regulations at least europian,allow use of cabels less than 2.5mm only for control purpose!
motors are minimum 2.5 mm!
its simply not worth the nusiance when the cable burns or over heats !
good luck


Please explain how a cable rated at 26a will 'over heat and burn' when pulling 6-7a

mikeref
25-05-2012, 09:26 AM
Please explain how a cable rated at 26a will 'over heat and burn' when pulling 6-7a R.B. Found this on a U.K. page. Seems there is some difference on rated amps per mm squared compared to your page.
( scroll down to table one and two in the link page)
I still think this rating is too high. Had a box a/c, (window shaker) running on a multi strand 1.5mm extension lead,(that wasn,t coiled up) and the test lead was getting rather warm.:eek: ..http://www.diydoctor.org.uk/projects/electriccables.htm

r.bartlett
25-05-2012, 11:50 AM
R.B. Found this on a U.K. page. Seems there is some difference on rated amps per mm squared compared to your page.
( scroll down to table one and two in the link page)
I still think this rating is too high. Had a box a/c, (window shaker) running on a multi strand 1.5mm extension lead,(that wasn,t coiled up) and the test lead was getting rather warm.:eek: ..http://www.diydoctor.org.uk/projects/electriccables.htm

I wouldn't use 1mm for anything other than lights and control. we now use 1.5 for the interconnect when we always used 1mm (it's only running the indoor fan and possible a condensate pump afterall. Of course regs state it should be capable of carrying the fuse load which can be 32a if a 12.5kw but few run a 4mm interconnect..(unless downrated by a smaller fuse at the outdoor unit )

goshen
25-05-2012, 12:05 PM
Hi
you can push any cable to its limit .
the regs tell you what is recomended, bottom line its your responsibility twards the customer.
using 1 mm cables is mostly limited to house hold small apliances ,and control.
when installing ref equipment indoores and outdoors, you may need to compensate for lentgh or whatever,
that is why we try to use only 3*2.5mm .
by us the diffrence in price is minor.
3*1.5mm=max 10amp
3*2.5mm= max 16amp
3*4mm= max 25amp

cadwaladr
26-05-2012, 01:20 AM
as i said the cable was changed,but when i look at my power supply to my house i wonder if 2.5 running a 30 amp ring main is underated? someone pointed out to me do not know if it is fact but no other country use,s our method of domestic wiring and we do because of the shortage of copper many moons ago.

mikeref
26-05-2012, 08:26 AM
When my place was wired, several owners ago, there was not much you could run on electricity.:rolleyes: Rubber insulated wire. Now with everything imaginable that chews power out there, wiring was upgraded to 2.5, except for hot water, (disconnected 10 years ago) that had to be 4mm, and stove. 4mm.
Of course, circuit breakers for individual areas, stove/ lights/ general power outlets etc.
40 amp pole fuse is now a 60, not that i use that much power. Average 60 KWH per week.

r.bartlett
26-05-2012, 10:55 AM
as i said the cable was changed,but when i look at my power supply to my house i wonder if 2.5 running a 30 amp ring main is underated? someone pointed out to me do not know if it is fact but no other country use,s our method of domestic wiring and we do because of the shortage of copper many moons ago.

A ring main is in fact 2 x 2.5 which means the circuit is well protected. 2.5 T&E is rated at 23a for a domestic situation therefore with 2 you are more than protected. Greater minds than ours have studied this and as a norm we always err on the side of caution.

http://www.electriciansforums.co.uk/electrical-wiring-theories-electrical-regulations/4511-ring-main-help.html

SeanB
26-05-2012, 02:08 PM
The only 1mm cable rated for 20A is a mineral insulated one, which will do double duty at that current as a heater element. Not used much these days, as it, along with the correct terminations, costs wounded buffallo.