There are some options that could cause the bulbs in a dimmable fixture not to start or dim:
- Not respecting the "burn in" time. A T-5 bulb in a dimmable fixture needs to be burned in. Reason is that the bulb(s) need the full energy of the ballast for a few hours to be prepared to work as well with low dimming intensity. This is why all Giesemann dimmable fixtures have an additional notice, informing people to respect the burn in time for the first 40 hours running. This is a requirement for all T-5 bulbs and has nothing to do if customer is using a Giesemann or other brand T-5 bulb. If a T-5 bulb is not "burned in" properly it might not start at the lower power stage and causes general problems by dimming these bulbs. Even ATI points this out in their instructions.
- Bad batch of lamps - Each Giesemann ballast is controlling two T-5 bulbs. Even if one bulb is not working properly (or damaged) the ballast will shut off the complete circuit (both lamps).
- Bulb not inserted correct - bulbs needs to be put into the lamp holder and turned by 90°. It is rather common to forget to twist the bulbs and as a result there is no electrical contact to ignite the bulb.
- Programming issue - Check if the bulbs are working in the manual dimming mode, by sliding the controller for each T-5 channel
- Using very cheap T-5 bulbs- many lower quality bulbs may not be capable of dimming: Usually higher quality bulbs are dimmable, but we can not attest for other companies bulbs and why we suggest the use of Giesemann lamps.