Appliance and Lighting Control
For appliance (and lighting) control, the toss-up is between hardwired control systems and wirefree control systems. Hardwired systems, typified by Polaron and C-Bus, require dedicated wiring, typically in a star topology, or close variant, whereby each light is supplied by a dedicated power cable which runs direct from the consumer unit, where the control gear is located, to the device under control. Control of the appliance is effected using a separate control circuit, which may be either mains powered or low voltage.
Wirefree systems are divided between radio operated switches and X-10, a system which uses the existing mains wiring to transmit the control signals. In terms of reliability neither of the wirefree alternatives is great. Radio based systems are susceptible to interference, and tend to drift with age, resulting in reduced operating range. X-10 is also susceptible to mains borne interference, from heavy equipment, switched mode power supplies and supressors. This issue is exacerbated by the fact that the majority of European X-10 equipment does not include status control, unlike its American counterpart, so it impossible to determine whether or not a command has definitely arrived at an appliance.
The X-10 Pro's and Cons
Cons...
- Reduced range, or complete loss of transmission when used in the proximity of switched mode power supplies (computers!), and Dell Rio MP3 players especially.
- Signal propagation can be affected by surge protectors.
- Relatively slow.
- Some models of X-10 dimmer switch require a neutral wire which isn't commonly found in UK installations; some models of X-10 dimmer always switch on to maximum brightness when sent an "on" command, rather than remembering the previous brightness level.
- A central controller is required to know the state of all X-10 devices in the house because of the lack of status support for European X-10 products.
- Can be problematic to control some types of lighting: dimmers are not suitable for flourescent and energy saving bulbs (although switches usually are); low wattage bulbs can sometimes be problematic due to local control leakage current (this can be disabled); low voltage halogen transformers cannot be guaranteed to work.
Pros...
- Very flexible - new control devices can be added quickly and easily.
- Relatively inexpensive (although costs can mount up over time).
- Can interwork with radio based wireless systems.
- Multiple devices can be controlled simultaneously (by selecting the same address), allowing for group addressing of table-lamps say.
- Plenty of third party control software available.
C-Bus Pro's and Cons
Cons...
- Requires extensive rewiring, including low voltage cabling to light switches and adoption of a "star" topology.
- Instant response to any command.
- More expensive than X-10; cost is mostly up-front since incremental installation isn't really feasible.
- Protocols are proprietary, although an interface to Comfort is available. Third party control software availability is limited.
- Only available to "trade", only supposed to be installed by an improved installer.
Pros...
- End users rave about the system and its features.
- Very flexible in terms of configuration capabilities.
- Very reliable.
Summary
X-10 has some fundamental limitations, but is very flexible - it can be retrofitted pretty much anywhere, and the controllers can be moved around on an ad-hoc basis from socket to socket. Hardwired systems are undoubtedly a better solution in terms of reliability and the control experience - they react instantaneously, and can be programmed to do ergonomic lighting scene changes. The ideal solution is probably a hybrid - with a hardwired system doing the majority of the work, and X-10 filling in the gaps where a bit more flexibility is required. Having painted a very negative picture of X-10, I have to say I have been very happy with X-10 control, despite its deficiencies. If it was feasible to retrofit a hardwired system, though, I would leap at the chance.
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