t-5's on a Workhorse ballast


New member
Is there a problem running 4 x 54w t-5 HO lamps on a Workhorse 7 ballst?

The wiring diagram and ballast specs say it works, but someone told me that he keeps burning out the first bulb. Could it be that it's wired incorrectly? I'd like to do a setup like this, but don't want any hassles.


Premium Member
If the first bulb is burning out it is most likely wired wrong. With a WH or any instant start ballast it is extremely important to connect/wire it properly. It sounds like the first lamps cathode might be wired in series which could be dangerous. The problem with instant start ballasts is if you wire them incorrectly they still light the lamps.

People have and are using the WH ballast but it is not designed for T5 lamps. T5 HO lamps are designed to be used on a ballast with an End Of Life (EOL) circuit. The EOL is designed to detect a failed lamp (cathode) or an open circuit. Without an EOL circuit the lamp will continue to operate but at a higher current until the lamp glass fails or the bulb seal fails. The lamp (glass bulb) can actually reach very high temperatures and could melt the endcap/socket.

Most lamp manufacturers recommend T5 spec program start ballasts. It starts the lamps the way they were to designed to be (preheats the cathodes before lighting) and they all have an EOL of safe operation.

I personally recommend T5 spec ballasts or at least a ballast with an EOL for safety.


New member
The Workhorse ballast is 'designed' in that it is capable of providing the current to run T5HOs - but like PaulErik said, T5s will last a lot longer if they aren't run on instant start ballasts.


Welcome to the next level
What if you use a starting cap? Would that help with the pre-heating of the cathode?

Im going to be using these (WH7) to run my T-5's on my prop. setup.


Premium Member
The WH / instant start ballasts will operate T5 HO lamps but is not the preferred type of ballast for T5 HO lamps.

You can not add a starting cap to an instant start electronic ballast. An instant start ballast has a high Open Circuit Voltage (up to 600V). This high voltage is used to ignite the lamps right when power is applied.

A programmed start type ballast first applies a low voltage to the lamp ends (cathodes) to bring the cathodes to the proper temperature and then applies a slightly higher voltage than the nominal operating voltage to ignite the lamps.

The most important thing to do if using an instant start ballast with any fluorescent lamp is to wire it correctly. The two pins at the end of a linear lamp must be connected together. The lamps must also be seated properly and all connections must be sound. The higher OCV has a higher risk of arcing.