Heat Pump - Dedicated Circuit

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Achh007

10 posts

Wannabe Geek

#306899 2-Sep-2023 10:45

Hi,

I am new on here so think this is the right forum for it, if not moderator please remove.

We have installed a 8KW heat pump (not a DIY, had a heat pump installer do it ). We stay in a body Corp with similar houses so some which have heat pumps have 8KW ones as it needs to cover a large area. I spoke with the installers a few times and they were ok that we could install it on the existing circuit i.e. we have a 25A MCB (COC would be given). We didn't want to run a cable through the lounge as the switch board is on the other side. I was still skeptical as other houses had gone through the roof (aesthetically not pleasing as the pipe shows on the outside) but I wanted it to be done correctly.

The installer and electrician came and were saying it will be fine on the current switch point but while investigating they found a few switches on that MCB and agreed that the roof is the way to go. The electrician went to the roof did his bit and when testing which MCB was it going through (I thought it was a dedicated circuit at the time). They found none of the MCB's but it was connected to an RCD, i thought both gave an "Oh" expression but connected it to the RCD. Later told me that we couldn't do direct as there is no space to put another wire to the switch board.

The heat pump has been working fine, no issues till date, I got a COC mentioning it was done on an extending circuit and tested fine on 25A MCB and working ok. They have an isolator outside as well.

I have since then questioned the company, stating the COC and what actually done was different, was verbally told the electrician has put a junction on the roof.

Now i need a bit of help on the below

Is it being on a RCD safe and legally correct?
By extending the circuit and putting a junction better than just using an existing power point which was near by?

I have already written them an email as I like to have things in writing and want to be sure the COC states what they have done.

Appreciate any help with the answers.

Tia

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4014 posts

Uber Geek

Trusted

#3122900 2-Sep-2023 11:20

Extending the circuit is fine as long as the wire gauge is large enough to handle it. A junction point is fine - no different to tapping off the back of an existing power point.

If you have a 25 amp breaker then the circuit must be capable of carrying the full 25 amps (with extra for overhead).

Your heat pump being an 8kw is probably going to draw about 9 amps of electricity and typical 2.5mm TPS electrical cable will carry 30 amps.

All circuits must now be behind an RCD if any wiring changes are made so having the heat pump protected by an RCD is indeed the correct legal process.

Did they mention if the RCD was actually an RCBO?
An RCBO is a RCD and MCB circuit breaker all-in-one device. Used in newer installations to have an RCD on each circuit so less other stuff is affected rather than a master RCD that cuts everything in the house.

Ray Taylor

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Achh007

10 posts

Wannabe Geek

#3122903 2-Sep-2023 11:29

Thanks so much for your reply Ray.

They didn't say much about the RCD but i have pic below which maybe helps - Does this answer your question?

In hindsight if there was no difference between the roof or an existing connection, I think i should have gone with their option of just using the existing power point would have been aesthetically much better plus saved me a few bucks too. A learning for me!

Appreciate your advice!

BadCo

109 posts

Master Geek

#3122915 2-Sep-2023 13:04

Does your house have LED lights? That is a lot of lighting circuits, I would have combined two of them and run a dedicated feed to the heat pump. Not necessary but it is good practice to have dedicated feeds to fixed wired appliances.

Oh if you do home automation with Home Assistant or similar, dedicated circuit means you can monitor the power draw of just the heat pump.

Achh007

10 posts

Wannabe Geek

#3122918 2-Sep-2023 13:26

Thanks for the reply.

We have a lot of lights and they are not LED - We have 2 floors and a basement.

In total I am thinking over 30 light bulbs (all are LED) - I guess that's why so many MCB's for them.

Our roof insulation is not up to the mark so thinking to reinsulate and to replace with LED's so it's safe

No Home automation sadly!! - I aint that geeky enough...lol

John19612

68 posts

Master Geek

#3122920 2-Sep-2023 13:42

raytaylor:

All circuits must now be behind an RCD if any wiring changes are made so having the heat pump protected by an RCD is indeed the correct legal process.

Are you sure about all circuits?

AS/NZS 3000:2007 (amendment 1+2) appears to state that additional protection (RCD) shall be provided for domestic electrical installation final sub circuits supplying, one or more socket outlets, lighting points, or directly connected hand-held electrical equipment. Clause 2.6.3.1.

Socket outlets added to an existing circuit shall be protected by an RCD. Clause 2.6.3.4. Typically, an A/C is fixed wired and RCD protection is not mandated. Of course, there is generally no reason why an RCD can't be used to provide additional protection if desired.

BadCo

109 posts

Master Geek

#3123008 2-Sep-2023 15:58

Achh007:

Our roof insulation is not up to the mark so thinking to reinsulate and to replace with LED's so it's safe

I would have done this before installing the heat pump. You will be wasting a lot of energy through loses in the roof insulation.

SomeoneSomewhere

1802 posts

Uber Geek

Lifetime subscriber

#3123014 2-Sep-2023 16:28

John19612:

raytaylor:

All circuits must now be behind an RCD if any wiring changes are made so having the heat pump protected by an RCD is indeed the correct legal process.

Are you sure about all circuits?

AS/NZS 3000:2007 (amendment 1+2) appears to state that additional protection (RCD) shall be provided for domestic electrical installation final sub circuits supplying, one or more socket outlets, lighting points, or directly connected hand-held electrical equipment. Clause 2.6.3.1.

Socket outlets added to an existing circuit shall be protected by an RCD. Clause 2.6.3.4. Typically, an A/C is fixed wired and RCD protection is not mandated. Of course, there is generally no reason why an RCD can't be used to provide additional protection if desired.

The new 2018 version I think requires more stuff to be on RCDs - but isn't mandated here. The installation manuals also often require them to be installed on an RCD, but NZ law does not require installers to follow those instructions.

RCDs have occasionally been known to nuisance trip when supplying inverter equipment, particularly at higher levels. If that occurs, you might want to contact the installers and ask for some kind of a fix. If not, no worries.

And for the avoidance of confusion: the heat pump is definitely protected by an MCB. The question is whether it's just an MCB, or an MCB and an RCD.

Sharesies

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Achh007

10 posts

Wannabe Geek

#3123024 2-Sep-2023 16:43

I would have done this before installing the heat pump. You will be wasting a lot of energy through loses in the roof insulation.

The heat pump is on the ground floor and it has been really effective in heating the whole house, as you know heat goes to the top floors really quickly.

Heat does come up and heats up a few rooms, the insulation will be my next thing in the to do list :)

Achh007

10 posts

Wannabe Geek

#3123032 2-Sep-2023 16:53

SomeoneSomewhere:

The new 2018 version I think requires more stuff to be on RCDs - but isn't mandated here. The installation manuals also often require them to be installed on an RCD, but NZ law does not require installers to follow those instructions.

RCDs have occasionally been known to nuisance trip when supplying inverter equipment, particularly at higher levels. If that occurs, you might want to contact the installers and ask for some kind of a fix. If not, no worries.

I haven't cranked up the heat pump yet, max I have taken it is to about 25. Do u think to put more load on it and test it out?
As it is a recent install the company will be more responsive then say 6 months down the line, in that situation where there is lots of load and it trips.

And for the avoidance of confusion: the heat pump is definitely protected by an MCB. The question is whether it's just an MCB, or an MCB and an RCD.

That's great to hear and sorry for a stupid question, this is what happened, the installer was downstairs and the electrician was in the roof. The electrician said turn the MCB's down as there was still electricity coming (in the roof wire I assume). The installer did it for all the lighting MCB's the electricity didn't go out, it only went out when he put the RCD down. That was where there was an "Oh" moment.

SomeoneSomewhere

1802 posts

Uber Geek

Lifetime subscriber

#3123122 2-Sep-2023 20:59

That's great to hear and sorry for a stupid question, this is what happened, the installer was downstairs and the electrician was in the roof. The electrician said turn the MCB's down as there was still electricity coming (in the roof wire I assume). The installer did it for all the lighting MCB's the electricity didn't go out, it only went out when he put the RCD down. That was where there was an "Oh" moment.

.

Hmm. Do you mean all the power MCBs? I would consider trying to work out which circuit it's on, because if it really is only protected by an RCD, that's a legal and safety issue.

I wouldn't worry about the potential nuisance trips. It'll usually happen on the first day if it's an issue.

Achh007

10 posts

Wannabe Geek

#3123129 2-Sep-2023 21:27

SomeoneSomewhere:
That's great to hear and sorry for a stupid question, this is what happened, the installer was downstairs and the electrician was in the roof. The electrician said turn the MCB's down as there was still electricity coming (in the roof wire I assume). The installer did it for all the lighting MCB's the electricity didn't go out, it only went out when he put the RCD down. That was where there was an "Oh" moment.
.

Hmm. Do you mean all the power MCBs? I would consider trying to work out which circuit it's on, because if it really is only protected by an RCD, that's a legal and safety issue.

I wouldn't worry about the potential nuisance trips. It'll usually happen on the first day if it's an issue.

You are correct, just checked the light MCB's are all 10A so I am guessing they were checking the power ones - I was near but don't remember

I got the feeling it's only connected on the RCD and not on any of the MCB's I could test it out, but based on what I saw the electricity to the roof only stopped when the RCD went down. The other MCB's didn't stop it. He marked AC on the RCD as well.

I am guessing the best way to check is to turn the heat pump on and one by one off the Power MCB's, if it doesn't turn off then it will be only on the RCD?

If that's the case is their an easy solution?, not sure how they gave me a COC if it's illegal and dangerous.

Thanks for replying, I do appreciate it!

SomeoneSomewhere

1802 posts

Uber Geek

Lifetime subscriber

#3123134 2-Sep-2023 21:37

Just realized I did not look closely enough at the picture. That's not (just) an RCD; it's an RCBO, which is a combination RCD and MCB. So all is fine.

Achh007

10 posts

Wannabe Geek

#3123135 2-Sep-2023 21:45

SomeoneSomewhere: Just realized I did not look closely enough at the picture. That's not (just) an RCD; it's an RCBO, which is a combination RCD and MCB. So all is fine.

Thanks so much mate, I was writing a stern email to them before I saw your message.

Appreciate your input and everyone else who has replied - It's been great being on here and amazed with the quality of technical responses.

Daynger

435 posts

Ultimate Geek

#3123217 3-Sep-2023 10:51

Achh007:

Thanks so much mate, I was writing a stern email to them before I saw your message.

Appreciate your input and everyone else who has replied - It's been great being on here and amazed with the quality of technical responses.

Actually the technical responses here leave alot to be desired.

While some are accurate, most are kinda sort right and others have bad if not completely wrong.

John19612

68 posts

Master Geek

#3123219 3-Sep-2023 11:02

Daynger:

Actually the technical responses here leave alot to be desired.

While some are accurate, most are kinda sort right and others have bad if not completely wrong.

I look forward to some spicy responses to what is probably the most accurate comment in this thread.

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