Air conditioning unit

[Elliott96]

Im putting a new circuit in tomorrow for an air conditioning unit (im just doing the supply side). Am I right in thinking a standard 30ma rcd and b type breakers can’t be used with air conditioning units?
Tia

 

[Pete999]

https://ampair.co.uk/products/panasonic-cu-5z90tbe/ Customers just sent over this. The run is about 100 meters from consumer unit in basement mainly clipped direct and in trucking up to the roof.

So are you just running the supply to the Compressor unit? or are you wiring the link to the condenser coil as well, and of course the Thermostat wiring also?

 

[telectrix]

Surely its better to have it on a rcd than not? I was going to install a sub db anyway as theres no spare ways so can install a main switch and chuck the rcd

a RCD is basically to protect persons from inadvertent contact with live parts. what is the chance of this happening in this situation?

 

[Elliott96]

what cable?

Going to use 10mm twin and earth inside the house and then armoured on the outside

 

[Elliott96]

what cable?

Going to use 10mm twin and earth inside the house and then armoured on the outside

So are you just running the supply to the Compressor unit? or are you wiring the link to the condenser coil as well, and of course the Thermostat wiring also?

just the supply!

 

[Pete999]

Going to use 10mm twin and earth inside the house and then armoured on the outside

just the supply!

Why 10mm2, what do your cable calculations tell you? have you done any? What are your plans for isolation purposes? Why the cable type change?

 

[James]

a RCD is basically to protect persons from inadvertent contact with live parts. what is the chance of this happening in this situation?

I actually have some experience with this.
totally unrelated job to put some cat 5 cable in above a ceiling grid.
put steps up, removed tile and poked head up for a look at what I'm dealing with.

my arm brushed against a piece of copper pipe and gave me a shock. not a belter but enough to make me flinch.

got tester out, 90v between earthed grid and this pipe,

traced it back to an air con unit outside, the incoming supply to outside isolator had been connected correctly but the outgoing side to the compressor had the earth connected to an empty terminal in the rotary isolator. so no earth to the unit.

 

[Elliott96]

Why 10mm2, what do your cable calculations tell you? have you done any? What are your plans for isolation purposes? Why the cable type change?

Yes I have its quite a long run, didnt want to be caught out would you go 6?

 

[buzzlightyear]

Yes I have its quite a long run, didnt want to be caught out would you go 6?

Is this a guessing game ?

 

[Pete999]

I actually have some experience with this.
totally unrelated job to put some cat 5 cable in above a ceiling grid.
put steps up, removed tile and poked head up for a look at what I'm dealing with.

my arm brushed against a piece of copper pipe and gave me a shock. not a belter but enough to make me flinch.

got tester out, 90v between earthed grid and this pipe,

traced it back to an air con unit outside, the incoming supply to outside isolator had been connected correctly but the outgoing side to the compressor had the earth connected to an empty terminal in the rotary isolator. so no earth to the unit.

Now you have inadvertently answered one of my questions to the OP.

 

[Pete999]

Yes I have its quite a long run, didnt want to be caught out would you go 6?

What cable size do your cable calcs say? guessing cable size is a bad move.

 

[Elliott96]

Is this a guessing game ?

No.... im using 10mm just asking someone else’s opinion.

 

[Deleted member 105166]

Usually Type C protective devices for air con.

 

[westward10]

No.... im using 10mm just asking someone else’s opinion.

If your circuit is getting on for 100m and using a 32A device 10mm is of inadequate csa for vd requirements.

 

[James]

I was going to use 70mm but haven't got enough space in the van for the drum so gonna go 10

or possibley

If your circuit is getting on for 100m and using a 32A device 10mm is of inadequate csa for vd requirements.

its actually less than 25A according to spec sheet. 10 is ok in my opinion for vd.
p.s. calcs done for swa

 

[westward10]

Several posts have been deleted. If you have nothing sensible to add leave the thread alone.