Additions to circuits – how much will it cost?

I often get asked to add one or more power points or light fittings, but how easy is it, and how much might it cost?

This is a much harder question to answer than you might think.

…How long is a piece of string?

…I can be fined or prosecuted depending on how significant my transgression is.

The new Wiring Rules (AS/NZS 3000:2018) is now 611 pages long. Some of the many rules that I might have to comply with are the following?

1. The number of points per circuit
2. Maximum demand per circuit
3. Maximum load per circuit
4. Length of cables
5. Voltage drop
6. The load on the consumer mains
7. Expected use
8. The circuit MUST work as intended

Some of these points are mandatory, some are guidance (but recommended).

While items 2) and 3) seem similar, they are both different; they need to be considered independently.

2) Maximum demand is an estimate of expected load – it is the expected loads based on years of evidence of general use and set by the regulators.

3) Maximum load is the connected appliance/s and how the appliance/s will be used.

4) cable length – this determines the following;

1. 1. Earth resistance,

1. 1. Earth fault loop (whether the circuit breaker or fuse will trip in the event of a fault),

1. 1. Capacitance (whether the RCD will operate correctly) and

1. Voltage drop (voltage drop is dependent on load but determines if your appliance will work or not).

These criteria are required to be within certain parameters and all are essential for the safety of the circuit and occupants. There is NO compromise in the Wiring Rules with regards to these parameters. Mandatory tests are also required to be carried out to determine if the circuit will operate within these parameters and is correctly connected and safe.

4), iii) Capacitance is an interesting one. While this may not have had an effect in the past, where fuses or circuit breakers were the primary overload/short circuit protection, home owners are now forced to install RCD/RCBOs (safety switches). There is no test for capacitance, but it is dependent on the cable length and the connected load. It has a significant effect on RCDs and will cause nuisance tripping. The longer the run, the more load, the more likely nuisance tripping will occur.

Should the RCD/RCBO experience nuisance tripping, I have failed in my obligations to comply with Clause 1.6, and therefore the installation is non-compliant with the Wiring Rules. Clause: 1.6 Design of an electrical installation, 1.6.1 General, (b) [the installation must] function correctly as intended.

Item 6)

Overload on Consumer Mains

This is something that is often overlooked by electricians (or they don’t care).

In old houses, a main switch was simply that – a switch. It turned the whole switchboard on, or off. There was no current (load) limiting. You can think of load as the power you are using at any particular time.

As consumers have changed the way in which they use electricity, homes have increased the number of power points, lights, air conditioning etc., the load on the consumer mains (the supply from the street) has increased. The result may be that there is an increased likelihood that the consumer mains will experience an overload.

Where consumer mains are overloaded, the cable insulation will start to break down; a fault may occur, there will be an increasing likelihood of a fire occurring.

Why?

All houses have fault current limiters – service fuses. These protect the switchboard, metering or consumers wiring from short circuits. The service fuses do NOT protect against overload, nor damage that may occur in the consumer mains.

If a fault occurs in the consumer mains which results in arcing, burning or a short circuit, the only protection that you have is the circuit protection in the nearest substation that supplies cables to your street.

This would be a very serious situation that would result in significant damage to your home.

What is overload current.

Most houses have either a 10mm, or a 16mm consumer mains. They may be single phase (2 wires), or three phase (4 wires). Occasionally two phases may be present (3 wires)

In most instances a 10mm consumer mains has a capacity of 50A, while a 16mm consumer mains has a capacity of 63A – according to the Wiring Rules.

But…

The maximum rating of the cable may be different in different circumstances. You may be able to achieve 63A on a 10mm cable, and 80A on a 16mm cable. Similarly a 10mm cable could feasibly be limited to 32A, and your 16mm cable limited to 50A if the cable is enclosed in thermal insulation.

Overload current is the current, above the rating of your consumer mains, that occurs when too many appliances are connected.

Why does all of this matter?

If you only have a main switch in your switchboard, there is no overload protection.

Should too much current (load) be present on your circuits, your consumer mains will overheat and the insulation of your cables will break down. This will either cause a fire, arcing, or a short circuit.

All of these possibilities are significant, and could feasibly be catastrophic for the occupants.

Am I just trying to make more money by over servicing?

Perhaps you think I am trying to get you to do more work than you need so that I can make more money?

Maybe you recently had some electrical work done and the other electrician didn’t say anything!

Well here’s some clauses from the Wiring Rules to clarify my statements.

Clause 2.5.1.2 of AS/NZS 3000:2018 (Clause 2.5.1.1 in AS/NZS 3000:2007), Overload protection of consumer mains shall be arranged in accordance with one of the following:

Note 5 (Note 6 in AS/NZS 3000:2007): Consumer mains supplying one or more circuits that are individually protected against overload should be provided with overload protection where the sum of the current ratings of the individual circuit-breakers so supplied exceeds the current-carrying capacity of the consumer mains.

So what does that mean in simple terms?

Let’s say I have a 10mm consumer mains – this generally gives us a 50A supply.

• two 15A power circuits – total 30A
• a 20A stove – 20A
• a 20A water heater –20A
• two 8A light circuits – total 16A
• The total for the combined fuses is: 86A – far in excess of the 50A consumer mains capacity.

What does this mean to the consumer?

If I am requested to add even one power point, I am expected to check the loading of the consumer mains and determine if the capacity can handle the increase in load –

Clauses:

8.2.2 (b) Consumer mains: (i) Current-carrying capacity

8.2.2 (c) Switchboard: (iii) Isolating devices e.g. main switches

On testing by the Supply Authority, if they find that I have failed in my compliance requirements, I will be issued a defect notice; I will have repair the installation and pay a re-test fee; I will be reported to Fair Trading for carrying out non-compliant electrical work.

Depending on the type of defect I may be expected to report to Fair Trading and explain why my work was non-compliant – I may then receive a fine.

If I receive too many defect notices, or too frequently, I may receive a significant fine; I may have my license suspended, be forced to undertake re-training; I may even lose my license.

Ok so this is related to the electrician, it isn’t your problem – or is it?

Should I carryout non-compliant work, I put the lives of your family at risk. Your house may burn down, or someone might be electrocuted.

Oh, I might also add:

I am insured, but ONLY if I undertake “compliant” work. Should I deliberately undertake “non-compliant” work, my insurance is void! Should your house burn down, you would have to chase me personally, and then sue me for undertaking non-compliant work that has caused your house to burn down!

So it is your problem! Why would you want that?

You got a cheaper quote

“But the other electrician I asked to quote didn’t tell me this, or didn’t agree with what you said.”

Well, maybe they don’t care, aren’t interested in complying with the Wiring Rules, or have no intention of submitting the mandatory CCEW.

That is the decision that clients have to make on a regular basis.

Yep, your “other” electrician was cheaper, but your house burnt down, a family member was injured, or you had to make other repairs in a few years time – whoops?

You might save a small amount of money now, but in the long term cost might be substantially more.

Non-compliance is rife amongst electricians

According to the Master Electricians Association of Australia, only 1-2% of the mandatory CCEWs are being submitted in NSW. This would imply that 98% of ALL electricians in NSW are operating illegally!

Don’t believe me?

Check for yourself – Phone them! Master Electrician’s Association

You could also contact the National Electrical and Communications Association (NECA), of which I am a member, to get their opinion.

Keep that in mind when you get a cheaper quote!

So…

…while this has become a very long discussion about required works and estimates…

When I suggest that you require extra works be carried out on your premises…

I am LEGALLY required to!

…but more importantly…

So is EVERY other electrician that quotes on the same job that I just have!

If they don’t, then they are not doing their job properly, don’t care about your family, or just want a quick “buck” out of it.

If the other electrician is cheaper, come back to me and I will explain why!

… you can then decide if they are really cheaper, or just not doing their job properly!

Bye for now,

Greg.
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#Charges #Costs #Overload #NonCompliance #FairTrading #Compliance #Fire #HouseFire #ShortCircuit