How to Estimate your Modular Wiring materials in minutes, #2 - Healthcare

Typical General Hospital

Why wait several days for a quote, when you can generate a bill of materials yourself in minutes, then issue it for simple comparative pricing?

Follow these simple steps and you will save days, freeing-up time to concentrate on the rest of your tender package. We are going to show you how to take one of the most difficult modular wiring projects, a Healthcare project, and from your Lighting and Small Power take-offs, produce a simple, yet accurate estimate and bill of materials.

MDBs/MDUs (Master Distribution Box/Unit)

Typical Master Distribution Box

1. Break MDBs down into No. of Ports required. Keep it simple. Assume separate Lighting and Power, and assume 9 Ports to be used throughout. (A different configuration may be pre-designed - even easier).

2. By DB, the quantity of lighting circuits used = the number of ports required. Divide by 9 = MDBs. If no circuits, assume circa 12 luminaires per circuit. If you don't want to 'locate' your MDBs and scale-off the Home Runs, then simply assume an average length of around 25m. Check where the DBs are and scale-measure the furthest group of circuits to gain confidence.

3. Power MDBs, like the Lighting, circuits = ports, so divide the total by 9, (per DB). If the design is not circuited yet, allow 6No outlets per circuit, and again allow an average Home Run length of around 25m.

4. The only other implications are whether you want a pluggable DB Header, and what cable sizes are to be specified in the Home Run, but for simplicity, assume non-pluggable Home Runs c/w a 4mm bundle within.

5. A good set of DB Charts is a great help if the design has progressed. Use the DB Charts and simply count the lighting and power circuits separately and divide by 9. An allowance of 'spares in the field' can be allowed-for at this stage. Keep an eye on cable size and type to exclude particular circuits from your system.

Lighting Materials

• 5c 2.5mm² Extenders, 5 Pole Tee, 5c 1.5mm² Luminaire Leads, 2c Belden/DALI (to PIR)

1. Qty of luminaires + PIRs + Wall Switches = Tees.

2. Qty of luminaires = 5c 1.5mm² Connection Cable, all 2m for eg.

3. Qty of PIRs = 2c 1mm²/Belden Connection Cable, all 2m for eg.

4. Qty of Wall Switches = 2c 1mm²/Belden Connection Cable, all 3m for eg

5. Qty Tees (No.1 above), = 5c 2.5mm² Extenders. Allow an average length/lengths peaking at 5m. (Scale-measure typical distances if available). Check for interlaced lighting layouts, this can increase the average length.

6. Spec may help identify where, if any, armoured protection may be required, or assume LS0H throughout. Often, high level cabling can be required to be armoured, with drops as flex.

7. Check for areas fed by standard DBs, but which are usually outside of modular wiring scope, such as stairwells (surface conduit), plantrooms (often hard wired), and externals (IP rated) - these can be fed via MDBs, but only to a local JB for wiring away.

Power Materials

• 3c 4mm² Extenders, 3 Pole Tee, 3c 4mm² Connection Cables, H/L Fused Spurs

• Radial system, using Tees and Drops

1. Qty of low level outlets = 3m 3c 4mm² Connection Cable.

2. Qty of mid/high level outlets = 2m 3c 4mm² Connection Cable.

3. Qty of high level ceiling void switched spurs = Pluggable Switched Spur

4. Qty of high level ceiling void un-switched spurs for safety systems = Pluggable Un-Switched Spur

5. Add 1-4 together = 3c 4m Extenders, allow an average length of around 8m.

6. Add 1-4 together = Qty of Tees

7. Check for areas fed by standard DBs, but which are usually outside of modular wiring scope, such as stairwells (surface conduit), plantrooms (often hard wired), and externals (IP rated) - these can be fed via MDBs, but only to a local JB for wiring away.

That's it! Issue your list to the modular wiring manufacturers and they will appreciate that it is simpler to quote a list of materials than it is to work through the tender enquiry themselves.

When left to the manufacturers to quote, in their defence, detail is often missed from the client, leaving them to make assumptions themselves. If you send your tender for a number of quotes, you will find you have a variety of interpretations returned.

For further help, advice or assistance, please contact us, visit our website, subscribe to Newsletters, and keep in touch for further articles, free advice and downloadable tools. We will create further articles in this series, identifying how to apply take-offs across all the sectors. If you don't feel comfortable doing these processes, please engage with us and we'll create the materials list required for any project.