I've been out of the system for years however here is what I remember and I will also be putting up a link to the state statutes that cover emergency lighting.
Red/White - Fire and Ambulance (must also have one rear facing amber)
Red/White - Fire Chief
Green - Vol EMS
Blue - Vol FD
Amber - Maintenance Vehicles - tow truck plows, etc.
Red and Blue was reserved for Law Enforcement
I am sure that this had to change by now but back in the day, Federal LE used to be Blue as well. I am sure that had to be updated to Red/Blue also
Blue light and Green light permits are issued by the chief of a department to membership although the chief can designate someone under him/her to issue but while reported to DMV, DMV does not issue these
DMV does issue the Red/White and Red/White with siren.
It used to be legal to have red lights as long as they faced the rear however because of problems way back when that was stopped as well.
Here's the link to the actual DMV Regs:
DMV: Flashing Light Permits
These are the CT General Statutes (Laws) that apply as well -
Sec 14-80f - Mechanical Equipment (sirens)
Sec 14-96p - Special restrictions on lamps. Flashing Lights.
Sec 14-96q - Flashing or revolving lights. Authorized use of blue or green lights.
Sec 14-283 - Rights of Emergency Vehicles.
Hope this helps.
Also, as far as responding with lights in a POV, a lot of insurance companies will not cover you if you are involved in an accident responding to a call. Some will even cancel your policy. I also called California Casualty which is an insurance company that pretty much caters to public safety workers. They told me that their policy regarding vehicles and emergency lighting (for Connecticut) is you are not to respond using a personal vehicle they will not cover you. They do have some kind of rider that they offer but it is separate from your policy. They outright advised that if you are involved in an accident responding to a call in your personal vehicle they will not cover you no matter who's fault the accident was. The woman also said some companies consider that business use of a personal vehicle and that can void your policy as well.
Also, the use of Blue and Green lights in Connecticut DO NOT give you any special priveledges. They are merely "courtesy lights". People "may" grant you the right of way but they do not have to. Also, you can not blow through traffic lights or stop signs. In reality, even full blown emergency vehicles are supposed to come to a stop and then proceed through a red light or a stop sign. Full blown emergency vehicles running code are also required to exercise "due regard" when responding. Blow through a light even running RLS without slowing down or looking out for other vehicles and you are liable as well as whatever service you are driving for.
I have been "out of the business" per say since 2002, however, I don't think things have changed that much over the years. There are also problems with abuse of the lights and impersonation issues as well. To be honest and anyone who has been in any branch of public safety will advise you that even responding to a call RLS, you may cut a few minutes but you really don't cut all that much time off either.
It also adds wear and tear to the vehicle and places the operator and others in the way for possible injury. Do I think that we should respond to a call RLS if need be? Yes but there are a lot of studies out there that show the good and bad effects. I fully believe vehicles should have emergency lighting for on scene thats for sure. It tells the public to move over and protects you but once again, anyone who has been in the field will tell you that the general public doesn't excercise enough caution or pay attention around emergency vehicles period.
Sorry for the long winded info