Check before you fit
This diagram is a planning and visualisation aid. It is not a certified design, a set of fitting instructions, or any guarantee that a system will be safe or compliant. Every wire size, fuse rating and part shown is an estimate. Confirm each one against the manufacturer's data and the current UK wiring regulations (BS 7671) before purchasing or making any connection. The installation must be carried out or signed off by someone competent to do so. Manufacturer names and logos are the property of their owners; BMS Technologies Ltd works independently of them.
This disclaimer applies to every wiring diagram, installation guide, calculation, automated check, component listing and parts list we produce (referred to here as a "diagram"). It forms part of the BMS Technologies Ltd Terms of Service. If you use a diagram from us, you accept what follows; if you do not accept it, please do not use the diagram.
1.What a BMS diagram is for
A diagram from us is a way to picture how a system might go together and to plan it through before committing to anything. It is a starting point for your own thinking, not the finished article.
It is not a completed design, a fitting manual, a replacement for the judgement of a competent person, or confirmation that any system meets the law or any standard. Nothing we produce should be read as ready to buy from or ready to install.
2.We are not acting as your engineer
We do not give electrical or engineering advice, and using one of our diagrams does not put us in the role of your electrician, engineer or adviser. If you act on a diagram without having it checked by a suitably competent person, you do so at your own risk.
3.Wire sizes and fuse ratings are estimates
Where our tools suggest a wire gauge or fuse rating, those figures come from general rules of thumb and the limited information in the diagram. Treat them as a prompt to check, never as a final answer.
They do not take account of how your system is actually built — for example the real length of each cable run, how cables are grouped or routed, the temperature where they sit, how they are mounted, or voltage drop across long runs. They may also rely on component figures that are out of date or wrong.
Before you buy or fit any cable or fuse, work the sizing out properly against the manufacturer's datasheets and the current UK wiring regulations (BS 7671 / the IET Wiring Regulations), have a competent electrician or engineer review it, and allow for the conditions in your own vehicle that the tool cannot see. The final choice of cable and protection is yours.
4.Parts lists and component data
Any parts list we generate is a convenience, nothing more. It reflects only what you placed in the diagram, so it can carry wrong quantities, duplicates or gaps, and it will not include the consumables a real install needs (glands, crimps, heat shrink, fixings and so on) or any allowance for offcuts and spares. Listed products may also have been changed or discontinued by the manufacturer.
In the same way, the component figures we show — voltages, currents, terminal counts, ratings and compatibility notes — can be incomplete or out of date, since manufacturers revise their products without telling us. Always confirm parts, quantities and specifications against current manufacturer datasheets and your supplier before ordering, and have your full parts list checked by someone competent.
5.Templates and example layouts
Any template or example layout we provide is a generic reference only. It knows nothing about your particular vehicle, where the components will physically sit, how cables will be protected and routed, ventilation and heat, or exposure to vibration, damp and corrosion. Adapt and review every template for your own situation, and have it validated by a competent person, before you buy or connect anything.
6.Automated checks
Our tools may flag possible problems automatically — a missing fuse, a voltage mismatch, an unfinished connection. These checks are simplified and will miss things; they may also be wrong. A diagram that passes every check is not therefore safe, correct or compliant, and a clear result is not an approval or a sign-off. Use the checks as a nudge, not as proof.
7.The output is only as good as the input
What a diagram shows depends entirely on what you put in: the details you enter, the parts you pick and how you wire them together. Mistakes, missing items or unusual conditions can produce a result that is misleading or unsafe, and the tool cannot judge your real-world intentions or the quality of an install. Making sure a diagram genuinely reflects the system you intend to build is your responsibility.
8.Safety, regulations and sign-off
Working on electrical systems carries real risk — fire, electric shock, damage to equipment, and injury or death. We do not promise that any system based on our diagrams will be safe, legal, insurable or approved for use, and meeting the regulations and standards that apply to you is your responsibility.
Before a system is put into use it should be reviewed by someone properly qualified, such as a competent auto-electrician, a registered electrician or a suitably qualified electrical engineer. That review matters most before you buy components, run and connect wiring, work on batteries or inverters, or connect to a mains or shore supply.
9.Availability and your saved work
Our tools and diagrams are provided "as is" and "as available". We cannot promise the service will always be running or error-free, that saved projects and exports will always be kept, or that templates, checks and component data will stay the same. Keep your own backup of anything you need.
10.Your acceptance
By using a BMS diagram you accept that the way you read and use it is down to you, that you take on the risks of designing, fitting or altering an electrical system, that you will check the design, the calculations and the parts independently, and that you will obtain a competent review where one is needed.
11.Limit of our liability
So far as the law allows, BMS Technologies Ltd and the people who work on its behalf are not liable for any loss, damage or injury arising from the use or misuse of our tools or diagrams — including indirect or consequential loss, lost data, lost profit or business, and damage to property. The limits and exclusions in our Terms of Service apply. Nothing here removes or limits liability for death or personal injury caused by negligence, for fraud, or for anything else that cannot lawfully be excluded. Nothing in this disclaimer affects your statutory rights as a consumer.
12.Trademarks and independence
Victron Energy, Renogy, Dometic, Blue Sea Systems, BEP and any other product names, logos and brands shown are the trademarks of their respective owners. BMS Technologies Ltd is independent and is not affiliated with, endorsed by or sponsored by any manufacturer; we refer to their products only for identification and compatibility.