Air conditioning installation - supply options

[bigfella9852]

Hello,

We are having 2 wall mounted split system air conditioners installed. These come supplied with a 13amp plug which will power both the internal and external units.

I would like to wire these in for a more permanent and neat installation. Our consumer board only has a single "RCD Protected" side which now has all of the MCBs populated.

There are 2 spare unused 16amp MCBs on the "Non RCD Protected" side, will is be OK to use one of these to supply 2 fused spurs, one for each unit? Or should they be RCD protected? If the latter, I was thinking of using 2 RCD faceplates. Grateful on opinions on the safest options please.

Thank you.

 

[Darkwood]

Welcome to the forum

2 things denote the requirement for RCD protection, firstly the manufacturers instructions may specify RCD protection then secondly the installation methods of your new circuits may mean RCD protection is required for the cabling itself. Its not just a matter of a yes or no answer here, if you require rcd protection due to the manufactururs instructions then you could used the unprotected side of the board, install methods that do not need rcd protection then use a rcd/spur or rcd/socket outlet.

If you are unaware with installation methods and when rcd is required then I would recommend you get a competent Electrician in to do the work.

 

[bigfella9852]

Ok thanks, I will check the manufacturers documentation.

If it does not state I think I would prefer there to be RCD protection due to the fact there is power to the outside units. All cables will be surface mounted in conduit.

 

[Pete999]

If it turns out that the two A/Cs require RCD protection, and you only have two spare ways on the non RCD protected side of your CU feed the A/Cs via a RCD FCU simples.
And if you haven't already explored this option get permission to join the Trainee section, you will get more help and less grief, as we have some very good Mentors in this section.

 

[bigfella9852]

If it turns out that the two A/Cs require RCD protection, and you only have two spare ways on the non RCD protected side of your CU feed the A/Cs via a RCD FCU simples.
And if you haven't already explored this option get permission to join the Trainee section, you will get more help and less grief, as we have some very good Mentors in this section.

Thanks Pete, I think thats the route I will go down anyway - even if not specified by the manufacturer. I understand that only one of the MCBs needs to be used to feed both RCD FCUs, one spurred off the other.

 

[bigfella9852]

Thanks Pete.

I think I will use those RCD FCUs even if there is no requirement from the manufacturer. I'd rather have a belt and braces approach when it comes to safety.

I believe I am right in saying I can use just one of the C16 MCBs to feed both RCD FCUs with 2.5mm twin and earth, one spurred off of the other.

 

[telectrix]

first you need to know the combined load of the 2 units. no use on a 16A circuit if they pull > 8A each. might be better 2 use a separate 2.5mm radial for each. then if 1 goes faulty, you still have use of the other.

 

[Pete999]

What he said

 

[ian.settle1]

No spare ways on the RCD side but spares on the Non RCD side then why not fit RCBO's

 

[bigfella9852]

first you need to know the combined load of the 2 units. no use on a 16A circuit if they pull > 8A each. might be better 2 use a separate 2.5mm radial for each. then if 1 goes faulty, you still have use of the other.

Combined maximum load (when on heat mode) is 2x 7.5amp = 15amp.

Thought if I could use just 1 of the remaining 2 MCBs it still leaves me with a spare.

I did toy with the idea of using RCBO's, but finding stock of a 16amp MK RCBO is proving difficult. I'd also still need 2x FCU with the RCBO option, so thought using the combined RCD FCUs would be a good choice.

 

[tomspark93]

http://www.screwfix.com/p/mk-sentry-16a-30ma-sp-type-b-curve-rcbo/30877

my personal preference would be an rcbo and then two standard SFU's

Edit: Grammar

 

[Darkwood]

Combined maximum load (when on heat mode) is 2x 7.5amp = 15amp.

Thought if I could use just 1 of the remaining 2 MCBs it still leaves me with a spare.

I did toy with the idea of using RCBO's, but finding stock of a 16amp MK RCBO is proving difficult. I'd also still need 2x FCU with the RCBO option, so thought using the combined RCD FCUs would be a good choice.

Hi again, apologies for my post 2 last comment, I didn't realise you were an apprentice and thought you may be DIY, like has been mentioned earlier, the Trainee section would benefit you greatly and the best place to ask those questions expected of someone learning the ropes.

It's not essential to join up and the choice be yours but its an area tailored for Trainee's and you will be able to discuss your questions and queries with our Mentors and fellow Trainee's.
Just look down the list of forum sections and click on the access to the Trainee forum and follow the instructions and links.

 

[bigfella9852]

No problem, I will do that.

Turns out I have a spare 20a MCB on the RCD protected side running a radial circuit to a single unused socket. I will re-purpose this to become 2x FCU.

 

[Octopus]

No problem, I will do that.

Turns out I have a spare 20a MCB on the RCD protected side running a radial circuit to a single unused socket. I will re-purpose this to become 2x FCU.

I think you should stick a RCBO in and run them on a circuit so when they trip the circuit they don't affect other circuits....

 

[davesparks]

What exactly are you expecting this RCD to provide protection against?

There's no point installing an RCD just because it sounds like it's safer when all it will actually achieve is a false sense of security and not protect against any likely fault.




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