As Paul has said above refer to CoPTTM Section B14.1.
It cross references this:
LAND TRANSPORT RULE – VEHICLE LIGHTING 2004.
Section 11 Flashing or revolving beacons
11.1 Safety and performance requirements for beacons
11.1(1) A beacon fitted to a motor vehicle must be positioned to ensure:
- (a) maximum visibility to other drivers and other road users;
- (b) that the main direction of the light emitted by all light sources is approximately parallel to the ground.
11.1(2) The light emitted from a beacon fitted to a motor vehicle must be a consistent cycle of light with a frequency of 2 to 4 Hertz.
11.1(3) A beacon must not emit light of an intensity that dazzles other drivers or other road users.
11.2 Fitting requirements for beacons
11.2(1) An emergency vehicle may be fitted with one or more red beacons and one or more white forward-facing beacons.
11.2(2) An emergency vehicle operated by an enforcement officer may be fitted with one or more blue beacons.
11.2(3) A motor vehicle operated by a registered medical practitioner or a registered nurse or registered midwife may be fitted with one green beacon.
11.2(4) The following motor vehicles may be fitted with one or two amber beacons:
- (a) a vehicle recovery service vehicle;
- (b) a vehicle operated in accordance with a traffic management plan approved by a road controlling authority;
- (c) a vehicle for which the use of the beacon is necessary to warn road users of a hazard due to the presence of the vehicle or of persons carrying out a lawful activity on the road in the vicinity of the vehicle.
11.2(5) An overdimension motor vehicle must be fitted with an amber beacon, in accordance with Land Transport Rule: Vehicle Dimensions and Mass 2002.
11.2(6) A pilot vehicle must be fitted with amber or purple beacons, in accordance with Land Transport Rule: Vehicle Dimensions and Mass 2002.
Cheers
Stephen