Posted by Doug Root on January 13, 2016
This morning I was out working the sales counter at Atlanta Light Bulbs. Our sales counter caters to electricians, contractors, municipal government accounts and property managers. I was helping one of our lighting contractors who typically services banks, retail stores and commercial buildings. He needed a medium base 175 watt metal halide and he wasn't sure if it was the protected version or the standard version. We got to talking about "protected" metal halide lamps and the question came up, "Why do they even have two versions of the same lamp? Why not just make the protected version?"
I thought for a minute and said, "Great question, let's answer it in a blog!"
The answer is fairly easy. The standard metal halide lamps have been around for decades. They have been used in walkway can lights, flood lights, wall packs and commercial indoor recessed lights. As the popularity of metal halide lamps grew in the commercial building markets in the 70's, 80's & 90's the demand for "MP" lamps skyrocketed and the price point on them was bit higher due to the extra components. So at that point you had both type lamps in the marketplace.
Lets break down a couple of lamp part numbers and look at the differences in the codes and the lamp itself!
MP means metal halide protected. 175 refers to the wattage. The MP function refers to the size of the neck on the lamp. A standard metal halide in 175W will have a fatter neck. The manufacturers create the lamps and the sockets for MP or open rated fixtures to work together. If you have an open rated fixture with an MP socket you will notice the socket is elongated and that the opening for the fixture socket is constricted to only fit the "skinny neck". In the Sylvania part number MP175/BU-ONLY/MED, BU means that the lamp can only be burned "base up" in our Prolume example above the U means Universal so it can be burned at any operating position. Only means that it really can be ONLY burned "base up". MED means E26 medium base. IC means Industrial Commercial rated.
MH means metal halide. 175 refers to the wattage. U means that the lamp can be burned "universally". So you can burn this lamp base up, base down or horizontal. In this code the IC is Prolume's internal code for Industrial Commercial rated.
The cost difference on these lamps is about $6.00
Now, in a mogul base lamp the same "MP designation changes the base of the lamp not the neck. The standard mogul base is a E39 mogul base and the protected or open fixture rated base is the EX39 mogul base.
Let's break down a 400 watt version of the MP and MH!
Again, MP means protected. 400 refers to the wattage. The BU refers to the burning position. Like the one above this lamp can only be burned in the "base up" position. In the Sylvania part number MP400/BU-ONLY, the only means you can "only" burn it base down.
The MH means it is a metal halide and rated at 400W. This one is universal burn like the one above and Industrial commercial rated! The big difference is that the MP lamp will always have a EX39 base and the MH lamp will always have an E39 base. When installing these lamps you will notice that if you try to put a non MP rated lamp into a MP rated fixture that the bulb will not turn on. The reason being is that the socket for the EX39 base is a bit narrow at the electrical contact point and that a standard E39 base will not make contact with power.
The key thing to remember when purchasing these lamps is that a MP or protected metal halide will ALWAYS fit where a standard metal halide will go. However a standard metal halide WILL NOT ALWAYS fit where an MP socket is installed.
If you want to be safe, always purchase the MP, they cost more but you know they will always work. The cost is the reason that two versions exist!
I hope this was helpful, if you have any questions give us a call a 1-888-988-2852!