What are the large square number lables that you see on the bottom and sides of street light fixtures? I see 10,15, 25, 40 etc. and the colour seems to be coded or something.

https://en.m.wikipedia.org/wiki/NEMA_wattage_label
The ones I know off the top of my head:
10:100w
17:175w
25:250w
40:400w
1x:1000w
Blue is mv
Red is metal halide. "PS" means pulse start
Yellow: HPS.

What are the large square number lables that you see on the bottom and sides of street light fixtures? I see 10,15, 25, 40 etc. and the colour seems to be coded or something.

Taken from Wikipedia - History of Street Lighting In The United States

There are three exceptions to this rule:

A "17" sticker adds a five to the power rating, and therefore, the light is rated at 175 watts.
If a sticker reads "X1," it describes a 1000-watt light.
If a sticker reads "3," it describes a 35-watt light.
Also MH stands for Probe Start Metal Halide, while PSMH stands for Pulse Start Metal halide.
Sticker colors:

Blue: Mercury vapor
White: Light-emitting diode
Soft White or Colored: Compact fluorescent lamp
Red: Metal halide
Half Red/Half White: Pulse Start Metal Halide (PSMH) (Can be used with HPS)
Yellow: Older HPS, LPS, and some induction
Orange: new sticker color, now used for HPS
Colors vary for new LED street lights such as black for Philips Hadco RX1 and RX2 or Green for BetaLED luminaires. The Induction fixtures usually contain a green and white sticker. Frequently seen power ratings:

"3" sticker - 35 watts (HPS/LPS)
"4" sticker - 40 watts (Induction)
"5" sticker - 50/55 watts (MV/HPS/LPS/PSMH)
"7" sticker - 70 watts (HPS/PSMH/MH/LED/Induction)
"8" sticker - 80 watts (Induction)
"9" sticker - 90 watts (LPS)
"10" sticker - 100 watts (MV/MH/PSMH/HPS/Induction)
"11" sticker - 110 watts (LED)
"13" sticker - 135 watts (LPS)
"15" sticker - 150 watts (HPS/PSMH/Induction)
"17" sticker - 175 watts (MH/MV)
"18" sticker - 180 watts (LPS)
"20" sticker - 200 watts (HPS/PSMH)
"25" sticker - 250 watts (MV/PSMH/HPS/Induction)
"27" sticker - 270 watts (LED)
"31" sticker - 310 watts (HPS)
"32" sticker - 320 watts (PSMH)
"35" sticker - 350 watts (PSMH)
"37" sticker - 37 watts (LED) - New: For BetaLED's luminaires in Boston, MA
"39" sticker - 39 watts (LED) - New: For BetaLED's luminaires in Boston, MA
"40" sticker - 400 watts (MV/PSMH/HPS)
"45" sticker - 450 watts (PSMH)
"60" sticker - 600 watts (HPS)
"70" sticker - 700 watts (MV)
"70" sticker - 70 watts (LED)
"75" sticker - 750 watts (HPS/PSMH)
"X1" sticker - 1000 watts (MV/HPS/MH/PSMH)
"X5" sticker - 1500 watts (MH)

Hey thanks for the detailed responses. Now I know what I'm looking at when gazing at streetlight fixtures

Hey thanks for the detailed responses. Now I know what I'm looking at when gazing at streetlight fixtures

Don't take this the wrong way but I'm surprised you didn't know all that already lol.  That was one of the first things I learned about HID fixtures growing up and that was before the internet was around.  This was way back when, when any questions I had, I had to wait until I saw the lineman out and this was one of the first questions I had.  "What are those different colored numbered stickers on the side of the fixture?"  He explained it all in detail for me, so I learned and figured it out.  God bless Wikipedia today lol!!  😀😀😀

Bucket175MV,  here ya go man.  This is where I learned what I didn't already know (like different fixture model numbers)

https://en.m.wikipedia.org/wiki/History_of_street_lighting_in_the_united_states

Bucket175MV,  here ya go man.  This is where I learned what I didn't already know (like different fixture model numbers)

https://en.m.wikipedia.org/wiki/History_of_street_lighting_in_the_united_states

Hey thanks and will check it out!