RCBO vs RCD consumer unit (用戶電箱) replacement(更換)

 

RCBO Vs RCD consumer unit replacement

If you are getting a consumer unit (fuse box) replaced and are unsure what your choices are, (you may not be aware that you have any choices) then read on. In this article I’m going to explain the difference between the two main forms of RCD (Residual Current Device) protection, RCD’s and RCBO’s

Everything discussed in this article will relate to a domestic installation and I am going to explain all the terminology used through out, click on the relevant links for further information on specific items.

This is a topic that often brings a glaze to peoples eyes but it’s as important if not more important than deciding on how many sockets you want in a room and you wouldn’t let someone pick that for you right?

First we’ll start at the beginning, the power supply coming into your home is split into multiple circuit that supply each socket, light and appliance. These circuit come from your consumer unit (fuse box). Each one of these circuits has to have two types of protection ‘over current’ and ‘Residual current’ these come in the form of MCB’s and RCD’s respectively.

 

 

 

Option 1 Dual RCD consumer unit

In a modern installation the most basic way to get ‘over current’ and ‘Residual current’ protection is to have what is called a dual RCD consumer unit.  This consumer unit has only two RCD units (as the name suggests) each of these RCD’s then feeds it’s own set of MCB which in turn are connected to the circuits in your home.  See diagram below.

In terms of safety you are covered as you have both ‘over current’ and ‘Residual current’ protection, but this is not the most practical solution in the real word. For example as one half of the circuits in your home are connected to each RCD when a fault occurs on just one circuit it will trip the connected RCD and the power will go out on half of your circuits. Not great if your working on your computer and a light bulb blows.

 

 

 

Option 2 RCBO consumer unit

The alternative is to separate the circuits up further and introduce RCBO’s, this device contains both an RCD and an MCB meaning both types of protection on one device. Each RCBO protects it’s own circuit so a fault on your lighting circuit will no longer effect the circuit with your T.V. of computer. See diagram below

The reasoning to have RCBO’s becomes clearer when you take a look a modern home or one that had been recently rewired to the latest building and wiring regulations. These properties usually have smoke alarms and intruder alarms, these kinds of devices are designed to be powered constantly and it would be more than an inconvenience if the power were to trip on these circuits.

 

 

 

Option 3 Dual RCD and RCBO consumer unit

RCBO’s can make your home an easier place to maintain and live in, although they are more expensive than the standard dual RCD consumer unit. Because of this extra cost some customer select a combination of a dual RCD consumer unit with a number of particular circuits protected on their own RCBO’s. the most popular circuits chosen are the smoke alarm, intruder alarm, fridge circuit, outside light circuit. see diagram below  

 

These is a combination for every home and budget, the most important thing is to have a good quality safe electrical installation that meets the requirements of the building and wiring regulations.

If you would like to have a consumer unit replacement or need to update your consumer unit to meet existing regulations please contact us or take a look at our services and accessories catalogue where you will find our installation costs.