Tips & checking techniques for your modular wiring materials
This article will try to give you an insight into various tips to improve the suitability and accuracy of your modular wiring package, regardless of what stage you are at.
Using the free download attached, carefully work through the list, considering each point while comparing it to your quoted materials, working drawings or delivery notes.
Main Distribution
You will have decided on whether your DBs are to be pre-fabricated with an additional header trunking to house suitable female sockets, which when fitted on site will accept the male connector from the home run.
Check the description of your MDBs to ensure they refer to 'non-pluggable' or 'pluggable male connector' or similar, so that they suit your options.
If 'pluggable DBs' are being utilised, you should have separate line items for your female sockets, which should be equal to the quantity of MDBs.
Glance down at general descriptions of cabling - look for references to Armoured or unarmoured cabling - does this match your options?
Consider home run lenghts that have been allowed. If these are just budgt figures at quotation stage, then review the average length. Check typical distribution zones for DB locations and potential 'furthest-points'. When the design is fully complete, you may end up with longer home runs than anticipated, and of course these are an expensive component.
Typically, commercial projects with central cores could average around 20-25m, whereas a healthcare project will have larger zones and can average circa 30m.
General Cabling & Materials
Like the main distribution, you should have an idea of the proposed system, so check for lighting materials that are suitable for either traditional switching as opposed to Dali strings for eg. For power, are you expecting Extenders, Tees and drops, rings, radials, part armoured, H/L fused spurs, check for switched V's unswitched.
Where you have conventional switching units, a power tee system, LCMs or FCUs, the average length cables feeding these items would all be circa 8-9m.
When switch units or tees are used, ensure the correct type and quantity of drops have been allowed, eg. 3c (1w), 4c (2w x2), 4c (PIR). Briefly;
No. of switch drops should match the No. of switch units.
No. of unswitched cables = No. of switch units. No. of switched cables = No. of luminaires.
Is luminaire lead length suitable?
Where a Dali system, (or equivalent), is utilised and the control equipment is back at the riser, only a series of 5c cables is required to link the luminaires, while a 2c, (network only) drops to the switching devices. On average these links are no more than 3-4m.
If connectivity is required to a 3rd party product, eg LCM, then ensure that materials to feed into and out of these units have compatible male/female connectors.
Is your power ring, radial, 20A, 32A, Tee system, loop-in/loop-out, or pre-wired flexible conduit away from the first point? Does your materials match?
3c 4mm throughout, or other cable sizes? HIE - 4c?
Do you have various length drops to suit different mounting heights.
One of the most common mistakes to make when working with manually generated spreadsheets is where quantities of cables are missed - ensure the quantities of cables match the accessories, like mentioned for lighting above, similarly for power;
Extenders are = tees which are = drops, (simple tee system)
Extenders are = spurs (fan coil only)
Extenders are = tees + spurs (H/L & L/L).
Exceptions to this is where cables are joined together to create a longer length.
Checking
If you can work through the above points and the attached tick-list, you are hopefully on your way to a smooth-running project. Any queries that arise should be discussed between the supplier, installer and design consultant. Some additional checks that may be worth a glance over include;
Is the project big enough to warrant an additional design/cad package - is this included?
Does the total cost in the 'total cell' equal the sum of the lines? Errors can occur here, again due to manual spreadsheets and human error, some formulas may be askew and some rows may have been added without totals being reset.
Excluded areas, assumptions, and document lists - has the supplier provided a clear scope of what has been provided?
When quotes are returned to the electrical contractors [you?], have they all allowed for the same type of system? For example;
If the spec calls for fully armoured throughout, has this been allowed-for by all parties?
Are the quantities of materials the same, similar or nowhere close, why not?
Does one company allow for pluggable DBs whereas the others do not?
Are exclusions and assumptions same/similar in their qualifying document?
Try to ensure estimates are like for like otherwise they can be misleading, where focusing on cost may not result in the correct system.
From all at Curo, we wish you a successful, error-free, on-time project. For any further advice on these points, please do not hesitate to contact us. Also please visit our website and sign-up for continued free advice and information.
Please contact Curo Modular Services for more information on 0191 516 6036 or info@curomodular.com
