Coloured Lamp lens/glass in Eevee

I’m trying to make an ambulance light in eevee, but I’m having a hard time setting up a red glass material that I can put a lamp behind and get a realistic result.

Has anyone else had any luck with this?

First of all, you need an object with thickness.
You can’t expect a material to produce refraction if material is on a surface like a plane.
Object geometry have to bound a volume which is deviating light rays trajectories.

Then, you have to enable refraction settings in Material tab and Render Tab.

And finally, lamp halo is only visible on reflections, not refraction. You have to create a sphere with an emission shader or a geometry reflecting light behind the glass to see something bright.

That’s wrong, you don’t need volume. The light rays simply never revert their angle as they never exit the ‘volume’.
I’m assuming OP wants an effect like those have, but with a tube and with the light inside… [The plane on the right has no volume.]

I don’t think this can happen “natively” in Eevee yet. If it could, it would be amazing.
Use a spot lamp that you manually tinted instead and increase its clipping distance or disable the glass material’s transparent shadows. In this case, the sphere is our ambulance light, with a point lamp inside.

I think you’re lucky you’re not trying to do church stained glass shadows.

You are right. I made a mistake while testing. I just pushed refraction depth too far.
We can see through a plane with a glass material.