Split load vs duel rcd

[machine]

Hi can someone please explain the differance between a split load c/u and a duel rcd unit for me

 

[GaryMo]

A split load has a number of ways that are protected by an RCD and a number of ways that arn't. This type of consumer unit was very common for installations carried out to the 16th edition of the wiring regulations.

A dual RCD consumer unit has two independant RCD's, each protecting a number of ways (6+6 for example). This type of consumer unit is more common for installations carried out to the current edition of the wiring regulations (17th).

The image below also has a number of ways that aren't protection by a RCD (A). Not all Dual RCD consumer units have this option.

 

[Taylortwocities]

There's a comprehensive guide here that will give you lots of background info.
HAGER GUIDE

 

[PrenticeBoyofDerry]

A duel RCD CU will have separate sides protected by it's own RCD, this will allow the circuits to be split in to two separate banks. allowing upstairs and downstairs, lights and sockets and other circuits to be separated in the CU, so if your RCD does trip out, it will not take all the supply in one area of the house out, sockets and lights for example. If arranged logically.

A split RCD CU, does have it's advantages as you can protect a number of circuits on the one RCD, but on the non protected side install RCBO's which will allow separate circuits an individual RCD protected device. This is handy as if one of these trips you know which circuit it is, with the RCD set up it could anyone of the circuits on that side that is causing the trip.
You could also apply a MCB which is not protected by any RCD device but special installation and materials should be used for this circuit that complies to BS7671:2008 requirements.