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Consumer Units Come in All Shapes & Sizes!



The Consumer Unit (or Fusebox) is at the heart of your electrical installation... it's what every bit of electrical equipment in your home, from lights to your computer, is powered from! All those different switches are really there to protect:


  • The cables from overheating (preventing fire)

  • Cutting the power in the event of a dangerous earth fault with an appliance and thus protecting you from an electric shock!!


If you have a Consumer Unit that looks like this then you will always have a recommendation for an upgrade (however, it is just a recommendation and never ever let anyone tell you it's illegal... which I've heard some scrupulous traders suggest!):

These are called BS-3036 rewire-able fuses... these wires will burn out in the event of a fault and then this cuts the power, you will then need to buy the correct sized wire to restore the power (see below). You do this by pulling out the fuse carrier, which in itself could be dangerous! These Consumer Units often had a plastic case but wooden frames within the casing... meaning they could catch fire and an electrical fault could case this to happen.

There 3036 Consumer Units, while outdated and don't offer full protection in the event of a fault, do still complete the job they were intended for.


Next up is the 17th Edition Consumer Unit (from January 2008 - January 2019)... these generally contained a "Dual Split Board" or two RCDs that protected two different sets of Circuit Breakers. For example, you would select Upstairs Lights and Downstairs sockets on RCD 1, and then Downstairs Lights and Upstairs Sockets on RCD 2. You might then have other circuits such as "garage" or "cooker" on other circuit breakers - either way these are balanced between the two circuit breakers.


These offer better protection than the older 3036 Consumer Units, they also protect you against electrical faults within accessories and detect an imbalance between earth and neutral and cut the supply, which the older "3036" Consumer Units could not do.


In the image below you can see the Main Switch (ON & OFF) to the left, with "RCD 1" immediately after and then, in this case, 7 Circuit Breakers that are protected by this RCD, then the other 7 circuits that are protect by RCD 2. The downside here, if there is a fault on one circuit then all of the other circuits power is cut! Not ideal... also, as the consumer you're unable to identify where the fault actually is!

We then move on to the more up-to date Consumer Units, the 18th Wiring Regulations, Amended in 2022! These contain individual circuits with each circuit protect by an RCBO, and in some cases an AFDD! AFDD's are the latest protective measures which far, far surpass those old 3036 Consumer Units. An RCBO is an RCD and Circuit Breaker combined, no wires are involved and if there is a fault, they switch off.. and providing the fault has passed, you can just safely switch them back on!


These newer Consumer Units are also metal clad and won't have any elements within them that are easily flammable... therefore, I hope that from reading this you will see that these newer units, especially if you're upgrading from a 3036, are worthwhile and much safer.


The video above shows an upgrade from a 3036 (first used in and around the 1960s) to an 18th Edition Consumer Unit with AFDD and SPD protection (although, for the keen eyed reader, the AFDD hadn't yet been installed as it hadn't been delivered when this video was made!).


If you wanted to read a more in-depth article into this you could have a look at this: https://electrical.theiet.org/media/2206/consumer-units.pdf


If you would like a Consumer Unit upgrade or find out more about Richard Speller, and Speller's Sparks LTD, then please do visit https://www.spellerssparks.co.uk or call Rich on 01761 325 007!





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