ComGas assesses and replaces consumer units and fuseboards in homes across Farnham, Guildford and the surrounding area, fitting RCD, RCBO and surge protection appropriate to the property and identifying every circuit before reconnecting it. Work is tested and certified on completion to BS 7671, the 18th Edition wiring regulations.
A consumer unit that matches how your home is actually wired.
Many consumer units still in service today were installed decades ago, before RCD protection was standard, before surge protection existed as a concept, and often housed in a combustible plastic enclosure that current regulations no longer permit for a new domestic installation. None of that makes a home unsafe to live in day to day, but it does mean an older board will usually be flagged during an electrical safety check, and it explains why a straightforward socket addition can sometimes turn into a wider conversation about the board itself.
We assess what's actually fitted before recommending anything — the enclosure material, the protection in place, the number of spare ways, and how the existing circuits are arranged — rather than quoting a like-for-like swap by default. Where the existing board is genuinely adequate and only needs a specific addition, we say so.
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How we approach a consumer unit change
Assessment, protection, identification and testing — in that order.
A consumer unit replacement is more than swapping a box on the wall. Every circuit is identified, the right protection is specified, and the finished installation is tested before anything is reconnected for use.
Board Assessment & Replacement
Before recommending a replacement, we look at what's actually installed — the enclosure, the protection devices, the age and condition of the board — and explain what it means in practical terms.
Rewireable fuses or an unprotected board are common reasons a consumer unit is flagged during an inspection
A combustible plastic enclosure is no longer acceptable for a new domestic consumer unit under current regulations; a like-for-like plastic swap isn't an option
Board condition, spare ways and cable entry points checked before a replacement is specified
Where the existing board only needs a specific addition rather than full replacement, we'll say so
Circuit protection has moved on considerably from a single shared RCD across half a house, and we specify it to suit how the property is actually used.
RCDs detect earth leakage and disconnect the circuit before it becomes a shock risk
A split-load board protects groups of circuits behind one shared RCD; a full RCBO board gives every circuit its own independent device
Full RCBO protection means a fault on one circuit doesn't take out everything else sharing that RCD, including things you'd rather stayed on
Surge protection devices are now required on most domestic consumer unit replacements unless a documented risk assessment says otherwise
Older homes accumulate circuits added over decades of DIY work and previous alterations, and not every board tells you honestly what each way actually feeds.
Every circuit traced and confirmed before it's reconnected to the new board, not assumed from existing labels
Unidentified or mislabelled circuits are common in homes with a loft conversion, extension or rewired kitchen added over the years
Accurate labelling fitted to the finished board so circuits can be identified quickly in future
Any circuit that can't be satisfactorily identified is investigated rather than reconnected on a guess
The finished installation is tested to BS 7671 before it's handed back, and any problems the testing uncovers are dealt with honestly rather than hidden behind a new board.
Full testing and certification on completion, covering earthing, bonding, insulation resistance and circuit protection
Existing faults on individual circuits — damaged cable, missing earths, incorrect connections — sometimes only surface once the board is opened up
Where that happens, we explain what's been found and scope any further remedial work separately before proceeding
A copy of the completion documentation is provided for your records
Protection that matches how you actually use the house
A full RCBO board protects the whole house without switching off the whole house.
A traditional split-load consumer unit puts a group of circuits — often half the house — behind a single shared RCD. If any one of those circuits develops an earth fault, the shared RCD trips and takes every circuit behind it out at once: lighting, sockets, sometimes the freezer or an alarm system, whatever happens to share that side of the board. It's not that the protection isn't working — it's working correctly — but the design means one fault has a much wider effect than it needs to.
A full RCBO board gives every individual circuit its own dedicated protective device, combining the RCD and MCB function in one unit per circuit. A fault on the kitchen ring only trips the kitchen ring. Everything else on the board stays live. It costs more than a split-load board because there are more devices to fit, but for most households the practical benefit — not losing lighting and every socket in the house because of one faulty appliance — is the reason we specify it as standard on a new board unless there's a good reason not to.
Split-load boards share one RCD across a group of circuits — one fault can trip them all
Full RCBO boards give each circuit independent protection
A fault stays isolated to the one affected circuit rather than spreading
Surge protection is now standard alongside RCBO protection on most replacement boards
Reviews from real ComGas customers, shown as submitted through Google.
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Lucie Victoria
15 May 2025
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Excellent service, highly recommend
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James Mowat
30 April 2025
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Incredible service — problems fixed perfectly once again.
Lee, Paul and the team at COMGAS are fantastic. They arrived on time and got straight to work, quickly identifying the root cause of the plumbing and heating issues I was experiencing.
The problems were diagnosed swiftly, I was kept fully informed throughout, and both issues were fixed with impressive speed and precision.
Having worked in the industry for nearly 20 years, I know how rare it is to find reliable, trustworthy, and genuinely skilled professionals — let alone a team this good.
I joked about it at the time, but it’s true: I had the best shower I’ve ever had in this house after they finished the job — and I’ve lived here for 10 years!
I honestly couldn’t ask for more and can’t recommend COMGAS highly enough.
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Faz
31 March 2025
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ComGas replaced my boiler and water tank at short notice. So glad i used them. Thank you
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Laura Andrews
26 March 2025
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Lee came out to the school I work in to look at a problem with our heating, he diagnosed the issue and was able to fix it on the spot in a neat and tidy manor. Would highly recommend
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Chloe
26 March 2025
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I recently used Comgas for a gas and heating service, and I couldn't be more impressed! From start to finish, their team was professional, friendly, and highly knowledgeable. They quickly identified the issue with my heating system and explained everything in detail, offering both short- and long-term solutions.
The technician was punctual and took extra care to ensure everything was running smoothly. I really appreciated their attention to detail and how they made sure to clean up after the work was completed. My home is now warm and cozy, all thanks to their expert service. I highly recommend Comgas for anyone looking for reliable, efficient, and trustworthy gas and heating professionals!
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Bec Newey
8 July 2024
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Messaged Lee on a Sunday evening with request. Instant reply that evening and engineer came next day. Polite, professional and helpful. Thorough investigation and speedy resolution to a leak with sink in wc. Happy customer.
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P Duffy
2 April 2024
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Scott and the team have served me well over several years. Skilled craftsmen. Dependable careful and very cosy-effective. I highly recommend them.
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Cilla Trout
22 March 2024
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Definitely recommend friendly reliable service
Scott was helpful and reassuring regarding our boiler answered our concerns and explained the problem and best course of action thank you for your advice
Consumer unit questions
Frequently asked questions.
If your consumer unit has been flagged in a report, or you're planning an addition and aren't sure whether the existing board can take it, get in touch and we'll assess it properly.
Why did my consumer unit fail my electrical safety check?
Usually one of a small number of reasons: rewireable fuses instead of circuit breakers, no RCD protection, a combustible plastic enclosure, or physical damage or overheating on the board itself. The report will classify exactly which observation applies and why.
What's the difference between an RCD and an RCBO?
An RCD detects earth leakage and disconnects a group of circuits sharing it. An RCBO combines RCD and overload protection for a single circuit only, so a fault on one circuit doesn't affect the others sharing the same board.
Do I need a surge protection device fitted?
On most domestic consumer unit replacements, yes — it's now required by BS 7671 unless a documented risk assessment concludes it isn't necessary for that specific installation. We carry out that assessment as part of the job.
Is a plastic consumer unit still allowed?
A plastic consumer unit already installed isn't automatically unsafe, but current regulations require a non-combustible enclosure for any new domestic consumer unit, so a like-for-like plastic replacement isn't an option we can fit.
Can you upgrade my consumer unit without a full rewire?
In most cases, yes — a consumer unit change is a distinct piece of work from a rewire, and the existing circuits are tested, identified and reconnected to the new board rather than replaced. We'll tell you if what we find suggests a wider rewire is genuinely needed.
What happens if you find unsafe wiring while changing the board?
We stop, explain exactly what's been found and why it matters, and scope any remedial work separately before proceeding. We won't reconnect a circuit we're not satisfied is safe.
What is a split-load consumer unit?
A board where a shared RCD protects a group of circuits rather than each circuit having its own individual device. It's a legitimate design, but it means one earth fault can trip everything sharing that RCD at once, which a full RCBO board avoids.
