Marelex Electrical - Switchboard Manufacturer

15/12/2025

Is it time for switchboard electricians to be recognised as a dedicated trade stream? Nevill Williams, General Manager, Specialist Electrical Solutions , and member of NESMA Queensland thinks so, and provides his thoughts on what we can all do to achieve this. Australia’s switchboard manufacturing...

13/12/2025

26/11/2025

🔹 𝟏. 𝐋𝐨𝐚𝐝 𝐂𝐚𝐥𝐜𝐮𝐥𝐚𝐭𝐢𝐨𝐧
𝑪𝒐𝒏𝒏𝒆𝒄𝒕𝒆𝒅 𝑳𝒐𝒂𝒅 = Σ(P).
𝑫𝒆𝒎𝒂𝒏𝒅 𝑳𝒐𝒂𝒅 = Connected Load × Demand Factor
𝑫𝒊𝒗𝒆𝒓𝒔𝒊𝒇𝒊𝒆𝒅 𝑳𝒐𝒂𝒅 = Connected Load × Diversity Factor
𝑨𝒑𝒑𝒂𝒓𝒆𝒏𝒕 𝑷𝒐𝒘𝒆𝒓 (𝑺): S = √(P² + Q²)
𝐤𝐕𝐀 = kW / PF
🔹 𝟐. 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐂𝐚𝐥𝐜𝐮𝐥𝐚𝐭𝐢𝐨𝐧.
𝑪𝒖𝒓𝒓𝒆𝒏𝒕 (𝑰): (a) I = P / (V × PF) (Single Phase)
(b) I = P / (√3× V × PF) (Three Phase)
𝒌𝑽𝑨 𝑩𝒂𝒔𝒆𝒅: (a) I = (kVA × 1000) / V (Single Phase)
(b) I = (kVA × 1000) / (√3 × V) (Three Phase)

🔹 𝟑. 𝐂𝐚𝐛𝐥𝐞 𝐒𝐞𝐥𝐞𝐜𝐭𝐢𝐨𝐧.
𝑩𝒚 𝑪𝒖𝒓𝒓𝒆𝒏𝒕: I = P / (√3 × V × PF)
Select cable > I × 1.25 (for safety)
𝑩𝒚 𝑽𝒐𝒍𝒕𝒂𝒈𝒆 𝑫𝒓𝒐𝒑: Vd = I × (L × R × √3) (for 3ϕ)
Vdrop% = (Vdrop / V) × 100
💡 Allowable ≤ 3% for lighting, ≤ 5% for power.

🔹 𝟒. 𝐓𝐫𝐚𝐧𝐬𝐟𝐨𝐫𝐦𝐞𝐫 𝐄𝐬𝐭𝐢𝐦𝐚𝐭𝐢𝐨𝐧.
𝑻𝒓𝒂𝒏𝒔𝒇𝒐𝒓𝒎𝒆𝒓 𝑺𝒊𝒛𝒆 (𝒌𝑽𝑨) = Total Demand Load (kW) / PF
💡 Add 10–25% future load.

🔹 5. 𝟓. 𝐂𝐢𝐫𝐜𝐮𝐢𝐭 𝐁𝐫𝐞𝐚𝐤𝐞𝐫 𝐒𝐢𝐳𝐢𝐧𝐠.
MCCB / MCB = Load Current × 1.25.

🔹 𝟔. 𝐄𝐚𝐫𝐭𝐡𝐢𝐧𝐠 𝐂𝐚𝐥𝐜𝐮𝐥𝐚𝐭𝐢𝐨𝐧.
𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐄𝐚𝐫𝐭𝐡 𝐑𝐨𝐝𝐬 = Fault Current / (π × L × √r).
(Basic method – practical soil resistivity testing used)

🔹 𝟕. 𝐂𝐨𝐧𝐝𝐮𝐢𝐭 𝐒𝐢𝐳𝐢𝐧𝐠
𝐂𝐨𝐧𝐝𝐮𝐢𝐭 𝐅𝐢𝐥𝐥 𝐑𝐚𝐭𝐢𝐨 = (Σ cable area × 100) / Conduit Internal Area.
𝑀𝑎𝑥 𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 = 40%.

🔹 𝟖. 𝐋𝐢𝐠𝐡𝐭𝐢𝐧𝐠 𝐂𝐚𝐥𝐜𝐮𝐥𝐚𝐭𝐢𝐨𝐧.
𝐋𝐮𝐱 = (No. of Fixtures × Lamp Lumen × Utilization × Maintenance) / Room Area.

🔹 𝟗. 𝐒𝐨𝐥𝐚𝐫 𝐒𝐲𝐬𝐭𝐞𝐦 𝐄𝐬𝐭𝐢𝐦𝐚𝐭𝐢𝐨𝐧.
𝐒𝐨𝐥𝐚𝐫 𝐏𝐚𝐧𝐞𝐥 𝐒𝐢𝐳𝐞 (𝐤𝐖) = Load (kWh/day) / Sun Hours
𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫 𝐒𝐢𝐳𝐞 = 1.2 × Total Load
𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐀𝐡 = (Load × Backup Hours) / Battery Voltage.

🔹 𝟏𝟎. 𝐄𝐬𝐭𝐢𝐦𝐚𝐭𝐢𝐨𝐧 & 𝐂𝐨𝐬𝐭𝐢𝐧𝐠.
𝐐𝐮𝐚𝐧𝐭𝐢𝐭𝐲 = (Length × Number)
𝐂𝐨𝐬𝐭 = Quantity × Unit Rate.
𝐓𝐨𝐭𝐚𝐥 𝐏𝐫𝐨𝐣𝐞𝐜𝐭 𝐂𝐨𝐬𝐭 = Σ(Material + Labor + Overheads + Profit).

📏 𝐂𝐨𝐧𝐯𝐞𝐫𝐬𝐢𝐨𝐧 𝐅𝐨𝐫𝐦𝐮𝐥𝐚𝐬.
𝐤𝐖 𝐭𝐨 𝐤𝐕𝐀: kVA = kW / PF
𝐤𝐕𝐀 𝐭𝐨 𝐤𝐖: kW = kVA × PF
𝐇𝐏 𝐭𝐨 𝐤𝐖: kW = HP × 0.746
𝐤𝐖 𝐭𝐨 𝐇𝐏: HP = kW / 0.746
𝐤𝐖𝐡: kWh = kW × Hours.

🧮 𝐃𝐢𝐯𝐞𝐫𝐬𝐢𝐭𝐲 & 𝐃𝐞𝐦𝐚𝐧𝐝 𝐅𝐚𝐜𝐭𝐨𝐫.
𝐃𝐞𝐦𝐚𝐧𝐝 𝐅𝐚𝐜𝐭𝐨𝐫: DF = Maximum Demand / Connected Load.
𝐃𝐢𝐯𝐞𝐫𝐬𝐢𝐭𝐲 𝐅𝐚𝐜𝐭𝐨𝐫: DivF = Sum of Individual Max / System Max Demand.

🔥 𝐄𝐱𝐚𝐦𝐩𝐥𝐞.
Load = 150 kW @ 415V, PF = 0.9.
1️⃣ 𝐂𝐮𝐫𝐫𝐞𝐧𝐭: 𝐈 = 150000 / (1.732 × 415 × 0.9) = 232 A.
2️⃣ 𝐂𝐚𝐛𝐥𝐞 𝐬𝐢𝐳𝐞 = 232 × 1.25 = 290 A → 300A cable.
3️⃣ 𝐁𝐫𝐞𝐚𝐤𝐞𝐫 = 232 × 1.25 = 290 A → 300A MCCB.
4️⃣ 𝐓𝐫𝐚𝐧𝐬𝐟𝐨𝐫𝐦𝐞𝐫 = 150 / 0.9 ≈ 166 kVA + 20% = 200 kVA.

𝑆ℎ𝑎𝑟𝑒!! 𝐻𝑒𝑙𝑝𝑖𝑛𝑔 𝑜𝑡ℎ𝑒𝑟𝑠 𝑤𝑖𝑙𝑙 ℎ𝑒𝑙𝑝 𝑦𝑜𝑢 𝑡𝑜 𝑔𝑟𝑜𝑤.
Reposted from LinkedIn original by 𝐄𝐫. 𝐖.𝐀.𝐒𝐢𝐝𝐝𝐢𝐪𝐮𝐞

Call now to connect with business.

20/11/2025

Cutting-Edge Technology in Switchboard Manufacturing

Switchboard manufacturing is advancing significantly with cutting-edge technologies enhancing performance, functionality, reliability, efficiency, and sustainability. This post lists some of the advancements revolutionizing the future of electrical switchboards and what they offer.
For the full post see our website:
https://www.marelexelectrical.com.au/news/

Modular Designs and Prefabrication:
Digital Twin Technology:
IoT Integration:
Smart Connectivity:
Energy Management Systems (EMS):
Advanced Protection Devices:
Sustainable Practices:
Additive Manufacturing (3D Printing):
AI and Machine Learning:
Cybersecurity Measures:

Let me know if there is anything else in the comments.

12/11/2025

It was great Last weekend to attend The Annual National Electrical Switchboard Manufacturers Association (NESMA) Conference in Hobart. It was great to catch up with other business owners and had great time exploring different ideas and developments, and the sharing of experiences and information by the other members.
Great displays by this years sponsors and prizes.

Electrical

08/09/2025

https://www.youtube.com/watch?v=IgRpbFIHzPQ

New ad for Marelex

Marelex Electricalhttps://www.marelexelectrical.com.auStill building building building.

05/03/2025

Due to the imminent approach of Cyclone Alfred, our office will be closed on Thursday and Friday. Our management and engineering teams will be working remotely during this period.

For your safety, please:

Avoid floodwaters and stay indoors.

If you reside in low-lying areas prone to flooding, consider moving to higher ground until conditions improve.

Follow all official safety advisories and local guidelines.

Stay safe and take care during this challenging time.

19/11/2024

🎄 **Holiday Closure Notice!** 🎁

Dear Valued Customers,

We wanted to let you know that Marelex Electrical will be closed for the holiday season from December 23rd, 2024, and will reopen on January 6th, 2025.

We appreciate your support throughout the year and look forward to serving you again when we return.

Wishing you all a joyful and peaceful holiday season! 🌟

Regards,
Marelex Electrical Team

19/11/2024

https://www.linkedin.com/posts/marelex-electrical_iso9001-iso14001-iso45001-activity-7264774913159237632-TJSe/

🎉 𝗠𝗮𝗷𝗼𝗿 𝗠𝗶𝗹𝗲𝘀𝘁𝗼𝗻𝗲 𝗔𝗰𝗵𝗶𝗲𝘃𝗲𝗱! 🎉 We are thrilled to announce that Marelex Electrical has achieved triple ISO certifications!…

20/12/2023

🎄 **Holiday Closure Notice!** 🎁

Dear Valued Customers,

We wanted to let you know that Marelex Electrical will be closed for the holiday season from December 22nd, 2023, and will reopen on January 15th, 2024.

We appreciate your support throughout the year and look forward to serving you again when we return. Wishing you all a joyful and peaceful holiday season! 🌟

Warm regards,
Marelex Electrical Team

14/09/2023

Marelex Electrical got new front signs.

14/07/2023

Marelex Electrical is currently seeking an Electrical Fitter for a workshop-based manufacturing position in Lismore. The role will involve the assembly of switchboards and control panels in a workshop environment. These are full-time roles with immediate starts for the right candidates.

What we do:

Marelex Electrical is an Australian family-owned and operated Electrical Engineering company that has been in operation for 30 years. We offer custom-made control and automation products, switchboard and control panel manufacturing, and general domestic electrical services. We also provide qualified technical support.

What we are offering:
• Competitive hourly rates + Penalties
• Temp to Perm Position
• Immediate Start
• Lismore Based
• Mon-Fri, no weekend work

What we are looking for:
• Qualified Electrician.
• Experience in the Assembly of Electrical Switchboards & Control Panels.
• Experience with Panel Wiring & Testing.
• Experience with Hand Tools & Power Tools.
• Ability to Read and Interpret Electrical Schematics & Drawings.
• Attention to detail.

If you are interested in this role, please apply now.

Send your resume to [email protected] or [email protected] or contact us at 02 6621 5221