Running a 315W CMH 4200K Head on 240 Volts
Voltage is the only hardware difference between this and the 120 volt version. Same reflector, same lamp, same parts in the box. What changes is the current the head pulls. At the higher supply voltage the same wattage draws roughly half the amps, and amps are what fill a breaker. That arithmetic decides how many heads a single circuit will carry. Three or four on one run instead of one or two is a different room. The trade is that a 240 volt outlet has to exist before anything gets plugged in. Most garages and basements do not have one without an electrician. Commercial rooms usually do, which is why this build exists at all. Work out the circuit before the head arrives, not after.
Why the 4200K Lamp Suits Vegetative Growth
Four thousand two hundred Kelvin sits in the transitional band on any spectrum chart. That puts it in reach of a full cycle, but it earns its keep in veg. Blue-weighted light keeps internodes tight and structure compact, which is the whole job in that stage. Philips rate this lamp at CRI 90 with 34,300 lumens and 20,000 hours of life. High colour rendering is not vanity when you are hunting for the first sign of mites. The other common use is filling in beside HPS through bloom, where the cooler light broadens a spectrum that skews red. Our own lamp testing put the Philips at roughly five percent ahead of the next brand on total PAR. The honest limit is that ceramic halide no longer wins on efficiency against current LED. It wins on colour quality and on what a complete head costs. Lamps use the PGZ18 base and stay easy to replace.
Key Features
- Supply: Built for a 240 volt circuit, not a standard outlet
- Current draw: Roughly half the amps of the same wattage at 120 volts
- Complete head: Reflector, ballast and Philips lamp supplied together
- Lamp: Philips MasterColor CDM-T Elite at 4200K, CRI 90
- Growth phase: Transitional spectrum, most often run for veg
- Reflector: 95 percent reflective aluminium with vertical lamp mounting
- Lamp cord: Six feet between the head and the ballast body
- Lamp base: PGZ18, so replacement lamps are easy to source
Technical Specifications
| Specification | Value |
|---|---|
| Model | GB240VEH-942, Greenbeams Hobbyist |
| Lamp wattage | 315W |
| Supply voltage | 240V |
| Lamp | Philips MasterColor CDM-T Elite 315W T12 |
| Colour temperature | 4200K |
| Growth phase | Transitional / full-cycle |
| CRI | 90 |
| Initial lumens | 34,300 lm |
| Rated lamp life | 20,000 hours |
| Lamp base | PGZ18 |
| Lamp orientation | Vertical |
| Reflector | Aluminium, rated 95 percent reflective |
| Ray capture | Under 3 percent trapped in the reflector |
| Lamp cord | 6 ft |
| Included | Reflector, ballast, lamp |
| Version | Earlier Greenbeams generation |