A long time ago, lighting engineers realized that they would need fluorescent bulbs to work outdoors or under cold conditions.  There were several issues to overcome, but the most important were starting the lamp in cold temperatures and maintaining a high light output as well.  The development came into what are called generally high output fluorescent light bulbs.  These have a lower starting temperature than standard fluorescents and have a higher lumen output too.  The typical applications are outdoor lighting, sign lighting and coolers and freezers which need a lot of light maintained regardless of the cold temperature.  The most common type of these are still the T12/HO, but there are also T8 and T5 HO choices in today's market.  One of the ways that these are abbreviated is with the two letters HO.  If you ever see HO as part of the code number, you will know that they are high output fluorescent light bulbs.  You will find these in almost any length as they have many different lighting applications so they can be as little as 2 feet long and as much as 10 feet in some special cases.  Probably the most common is the 8 foot HO which has a code of F96T12/CW/HO.  This has been used in warehouses for decades because of the need for higher light levels, but many are being replaced these days with more efficient metal halide or T5 Pentron lamps.  Some of the most common codes you might find on a bulb would be F24T12/CW/HO, F36T12/CW/HO, F48T12/CW/HO, F60T12/CW/HO and F72T12/CW/HO.

As with all fluorescent bulbs, they rely on ballasts inside of the fixtures in order to make them work. The ballasts for the HO lamps are usually larger than the standard types, and put out a lot more heat.  Some of that is changing when it comes to electronic ballasts as they have a size that is almost the same as the standard electronic ballast.  The old style HO ballasts are very heavy as they have large windings inside.  The ballast is important because it is specific for each type of lamp.  You can't change from one type of fluorescent to another without changing the ballast in most cases.  Most of the time the ballast and the lamp are matched electrically and so it's good to make sure the ballast you have is the right one for the lamp you choose.  Another thing to watch for is that some HO lamps have a single pin end and others a recessed double contact end which does not match up to standard fluorescent light bulbs.

You can get these in almost any color you want including the more desirable full spectrum light.  The typical choices in the past have been cool white, warm white and daylight, but we also have them in some color correct phosphors.  The full spectrum has special phosphors that give it a similar color to daylight or natural sunshine.  It produces light the way our eyes naturally use it, giving better visual acuity and reducing problems like eyestrain.  The term full spectrum is primarily used when referring to those lamps that fall into the white to blue/white color temperature range.  It's these colors that are great for high output fluorescent light bulbs because they appear so much brighter and cleaner.  If you have a sign or a cooler which sells product, the full spectrum or daylight color brings out the great colors of product making them more attractive.  That could mean more sales or turning inventory faster.

Remember that there are many lengths of high output fluorescent light bulbs, we describe some of the general characteristics here.  We have a large inventory of HO fluorescent bulbs for nearly every type of light fixture in the field.  It's never a problem to get what you need and Sylvania is our preferred brand of this type of lighting.  If you need help identifying a bulb, our customer service representatives can help you determine by length or wattage what you have.