Generator size

by Rob Finnie
(Coupar Angus )


Hi, I started cake and coffee trailer in my local park with permission of the local council, however, somebody reported me to environmental health regarding noise from my generator. Electric wise I have a double door pie warmer, ice cream machine, fridge freezer and a separate freezer. The noisy petrol generator was 9.5kw, I have just spent £1200 on a 6.5kw “silent “ generator but it is no quieter than the original. Can anyone tell me the maximum size of generator I would need to run the above. The new generator is huge and I have had to put it in boot of my 4x4 just to try and muffle the noise a bit. Any help greatly appreciated.
Rob

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Dec 03, 2025
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starstarstarstarstar 		Generator Size for a Coffee & Cake Trailer – Simple Explanation
by: MobCater

Hi Rob,

You’ve not done anything wrong — this is a really common problem in mobile catering, especially when running a petrol generator near homes or parks.

Here’s the simple truth:

Your appliances are pulling more power than most small generators can handle quietly.
That’s why the 9.5kW petrol generator was loud, and why the new 6.5kW "silent" generator is still noisy. "Silent" only means quieter at low loads, not when running hard.

Let’s break it down in plain English.

1. How much power your equipment really uses

Most mobile catering trailers use around 5–7kW, but it depends on the ice-cream machine especially.

Typical power ratings:

Double-door pie warmer: 1.0–1.5 kW

Ice-cream machine: 2.0–3.0 kW (sometimes higher)

Fridge: 150–300 W

Freezer: 200–400 W

Extra freezer: 200–400 W

When everything kicks on at once, you can easily hit:

4.5kW minimum → up to 6.5kW peak → sometimes 7.5kW with spikes

So yes — a 6.5kW generator is technically big enough, but only if nothing spikes at the same time. Ice-cream machines are the biggest problem because they have heavy compressor start-ups.

2. Why your new generator is still loud

Petrol "silent" generators are only quiet when:

they run at light loads

they’re inverter models

they sit inside a proper acoustic box

Once you run them at 50–80% load, they all get loud.
Putting it in a 4x4 boot helps a little but can cause overheating — be careful.

3. What size generator you REALLY need

To run your setup safely and without noise complaints:

A 7kW–8kW inverter generator (LPG or dual-fuel) is the sweet spot.

Why:

LPG models are much quieter

inverter generators run at variable speed → less noise

7–8kW gives enough headroom for ice-cream machine start-up

LPG burns cleaner → no petrol fumes → environmental health prefer it

cheaper to run per hour than petrol

A 6.5kW petrol generator will cope,
but it will always be loud because it’s working near the limit.

4. How to reduce noise without causing problems

The safest ways:

Build a vented acoustic box (never fully enclosed)

Use rubber anti-vibration pads under the generator

Place it 5–6 metres away behind your trailer with an extension lead

Use sound-shielding panels on three sides (leave back open for airflow)

Switch to LPG — they run much smoother

Do NOT:

Fully box it in — fire risk

Run it inside a boot or van long-term — dangerous fumes + overheating

5. Environmental Health Rules (Simple Version)

They don’t set a maximum generator size —
they only care about:

Noise levels

Fumes

Safety (LPG, fire, CO risks)

If someone complained, they are likely pushing you to choose:

a quieter generator

an acoustic box

or LPG power

You’re not in trouble — they just want the noise managed.

6. The quick answer

For your equipment:

A 7–8kW LPG inverter generator is the best and quietest option. Your current 6.5kW petrol generator will always be noticeably loud under load. Hope this helps, best of luck.

Disclaimer:
This guidance is general information based on UK mobile catering experience. Always check your local council’s environmental health advice, follow manufacturer safety instructions, and ensure LPG or electrical work is carried out by qualified professionals.

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