New to the 18th Edition Wiring Regulations is the recommendation of AFDD’s. We LJD Electrical have put together a complete guide to help you better understand what an AFDD is, why and if you need one, how they work and the different types available for domestic dwellings.
An AFDD is an Arc Fault Detection Device and it is designed to detect the presence of dangerous electrical arcs and disconnect the circuit affected.
Why would I need an AFCC, I hear you cry
Before answering that question it is important to understand the existing protection scheme for a domestic electrical installation:
Additional protection – This is provided by an RCD's not exceeding 30mA.
Fault protection – This is automatic disconnection of the power and the fault, typically provided by circuit breakers, RCD’s, RCBO’s and fuses.
Basic protection – This is the insulation of live parts preventing the user coming into contact with them.
So what’s any of this got to do with AFDD’s?
Well there’s one type of fault that none of the above measures will protect against; electrical arcing within a cable or connection.
What is arcing?
An electrical arc is created when the electrical current jumps the gap between two conductive materials and if the current is comparatively low, a spark will be produced. If however the current is high enough a continuous electrical arc is generated where the air changes from a gas to a plasma capable of supporting the arc. The temperatures created by this arc can exceed 6000°C.
So why is there a problem
Put simply, an Arc fault can lead to fire.
Where could an arc fault happen?
The two most common areas for an arc fault to occur are firstly at cable terminations, where the termination is loose, and secondly within the cable itself where the insulation has been damaged.
If you have no AFDD’s fitted, there are a few warning signs to look out for:
Smell of burning coming from cables or socket outlets. Whilst there could be other causes other than an arc fault, the smell of burning coming from either cables or a piece of electrical equipment is not a good sign, similarly if the cable or equipment feels hot to the touch, turn off the circuit affected.
Scorch or burn marks on items of electrical equipment. Arcing may not be the primary cause of the scorch or burn marks, but again the affected circuit should be isolated.
A rapid or intermittent ‘clicking’ noise accompanied by a burning smell coming from inside your consumer unit. If you encounter this situation, turn off the circuit affected and, contact an electrician.
Remember you should always have smoke detectors fitted in your property
How much do AFDD’s cost?
At the moment, the cost can be seen by many as off putting when compared to other protective devices installed in consumer units. In all likelihood this will change over the coming years, as the demand for AFDD’s increases.
As AFDD’s are so new to the UK domestic electrical market it is very difficult to obtain a broad range of prices. The cost is currently sitting between £150 to £450 plus fitting per AFDD depending on its type, rating and the nature of the installation.
If you require further information on AFDD's and the cost of installing them in your own property then please do not hesitate to call LJD Electrical on
01604 751347 / 07974 683861
Here is a short video on AFDD's from our friends at Electrium Wylex
All of the above comes down to this essentially:
AFDD’s detect arc faults that other protective devices can’t.
AFDD’s will detect an arc fault that arises after an installation has been tested.
By detecting the arc fault the AFDD will prevent the initial cause of a potential fire
Expensive to install but cheaper then losing your property to fire.