Lighting Systems

High Performance LED Main Lights
LED based lights, with helmet mounted batteries, have virtually replaced Bulb-based systems, at least for new purchases, although many rechargable miners'-type lamps will remain in circulation for some time. Modern LED caving lamps are much lighter-weight, dispense with the need for a heavy waist-mounted battery, and last rather longer, and the very recent ones are at least as bright as the best halogen-rechargable miners' type lamps.

The technology is now such that a small, helmet mounted unit, using dry-cells or a small modern rechargeable battery (eg NiMh) can give a good light, with long or very long duration and minimal weight. This is a rapidly evolving field and the LEDs are getting brighter and cheaper with each generation. As of 2011, typical LED efficiencies are around 100 lumens per watt (compared to 10-20 for the best incandescent bulbs). Battery technology too is advancing rapidly so cavers can benefit from innovation from the mobile phone and laptop computer industries.

The long-duration and convenience of LED-based lights using dry-cells has also to a considerable degree displaced carbide lamps from use in expeditions. Unlike incandescent bulbs, LEDs are infinitely dimmable to extend run time. A typical modern expedition LED light will have over a hundred-to-one ratio in light output between highest and lowest modes.

Modern high performance LED main lights available in 2011 can be separated into two broad, and somewhat overlapping, categories. There are most expensive designs, which typically have a bespoke (often milled aluminium) enclosure, such as the Swiss Scurion, the Stenlight, and the Speleotechnics Nova. These lights cost hundreds of pounds, and include high performance lithium based rechargeable batteries also in custom enclosures. These have the highest performance, in particular as a metal enclosure is necessary to sink heat from the LEDs.

The other category consists of high performance lights retrofitted into existing cave proof enclosures. These include the Bisun and Pitlamp refits for Oldham/Speleotechnics headsets, and Solo-for-Duo and CustomDuo refits for Petzl Duo headsets. Maximum light output is limited by head dissipation through the plastic case, and the batteries used are typically of a less specialist nature.

{note - it would be good if some users can do write up on their lights based on experience}

Backup LED Lights
Smaller LED lamps are ideal as a backup to a brighter main light. Petzl and others make a number of neat headlights very suitable as backup lights, the Myo XP and Tika XP models especially so. Either of these units, or equivalents from other makers, are bright enough as main caving lights, are reasonably priced, and reasonably robust within limits, albeit not bombroof like a proper miner's lamp or a purpose-built caving lamp. Small LED torches can also serve as backups, eg those used by SCUBA divers, and can be permanently mounted on the side of the helmet. A backup light for caving does need to be at least somewhat robust, especially if permanently left on the helmet.

Traditional Waist Mounted Bulb
The traditional caver's lamp consists of a belt-mounted battery pack, connected via a robust cable to a helmet-mounted headset. This might be a lead-acid miner's lamp such as the "Oldham" (based on a 2-cell 4 volt battery), or a more modern unit based on 2, 3 or 4 NiCad (or equivalent) cells. Some of these are designed for mining such as the 6V Spanish unit, or specially for the caving market (eg Speleotechnics FX2, FX3 and FX5, and the "Kirby" lamp).

LED upgrades are available for the headsets, which offer massively increased runtimes (typically three times) with far greater light output and reliability of the LED bulbs vs. the breakage prone higher efficiency halogens. Simple screw-in replacements are available such as the TerraLUX screw ins as well as entire replacement light units such as the Bisun X2 / X3.

The Speleotechnics FX (and later DX) series of lights all have identical wing-nut arrangement for securing the lamp cord onto the top of the battery. The FX2 is relatively dim but was cheapest, the FX5 fairly cumbersome (often being seen in mines and larger caving regions), the FX3 (10hr duration with halogen bulb) was a fair compromise for tighter caves. The headset and moulded plug were interchangeable between batteries with a simple substitute of the correct bulb. The most recent DX series of Spelotechnic batteries were based around NiMh battery technology, charged with an advanced 'pulsed' charger. End of life failure modes of Speleotechnic FX batteries typically involved slow damage by grit to the copper-leaf of the battery connector, and of corrosion / bad contacts developing in the moulded plug of the headlamp cord where it attached to the battery.

The Kirby is also a pretty good unit, but after heavy use can suffer from damage to the cable where it enters the battery; the cable not being replaceable.

The Spanish miner's lamp [author's note - what are these actually called ?] is an excellent unit and perhaps the best commercially available unit of its type, though with the slight irritation that the normal 50mm caver's belay belt will not fit through the belt-loops. A narrower belt must therefore be used. No doubt there are other alternatives. At least some of these, especially those targetted at cavers, now come in LED versions, or hybrid with LEDs combined with a halogen bulb.

Many cavers have made their own units using commercial headsets and assembling batteries from NiCad or NiMh D-cells or F-Cells in a suitable case (usually 4 giving nominally 6 Volts). Properly made, these are very similar in performance and use to FX5, Kirby, or the Spanish lamp.

The lead-acid Oldham miner's lamp and its brothers can't really be recommended these days as it needs diligent charging if it to have a reasonable service-life, tends to get ruined by water ingress if swimming, and is very prone to acid leakage which is highly damaging to nylon SRT ropes and harnesses so a bit of a worry on SRT trips!

The distinctive stainless-steel cases of Nife lamps are still occasionally seen, though most if not all are now only cases for more modern sealed cells. Proper Nife cells are now really only of historic interest though they were were very robust and well-regarded, but were prone to leaking highly-caustic Potassium Hydroxide electrolyte which could cause nasty burns and damage equipment - especially polyester harnesses and ropes (thought polyester ropes are now less common).

Halogen bulbs are much brighter than equivalent non-halogen bulbs and well worth installing for the modest extra cost involved.

Although LED systems are rapidly gaining popularity, the belt-mounted miner's type lamp with a halogen bulb still gives a good light, at least with the 6V versions, albeit with shorter burn-time and much greater weight. However the incandescent bulb's days are probably numbered given the continuing advances in LED lighting systems and battery technology once those in service reach the end of their useful lives.

Carbide
Carbide / Acetylene lamps were once quite a popular choice of caving lamp, and still (just about) have a place for expedition caving where recharging batteries may be impractical. Calcium Carbide(CaC2) gives off acetylene gas (C2H2) when water is added, producing calcium Hydroxide (lime, Ca(OH)2) as waste-product. The acetylene is then burnt to give a bright wide-beamed light. Back in the even-older days carbide lamps were used on bicycles and even on cars. The traditional UK caving lamp was the "Premier" cap-lamp or "Stinky". It was originally made for miners rather than cavers: for metal mines not coal mines obviously! The gas generator and burner is a single unit which mounts on the helmet. It lasted perhaps a couple of hours on fill of carbide. The light was quite good if fitted with a larger-sized reflector, but was very hard to light once the flint igniter got wet, and barely reliable at the best of times. Most were relegated to the mantelpiece when electric miners' lamps became available / affordable.

Though some still have fond memories of the old Premier stinky, others (including the author) regard them as unreliable and an infernal nuisance. A much more practical proposition is the "expedition" carbide, with a separate generator hung from a belt, linked to a burner and reflector on the helmet via a pipe. These give a terrific light, and anything between 5 and 10 hours on a fill of carbide (given several fills of water). Most have a piezo-electric ignition system which is vastly superior to the flint on the old stinky. They still require a fair bit of skill and perseverance to master. Normally a small electric head torch is carried as a back up for when the flame goes out in a waterfall, or at highly-inconvenient moment half-way up a pitch. A number of different generator units have been available, the most popular is perhaps the Fisma, subsequently marketed by Petzl. This is a robust, agricultural-looking item, which works well once mastered. Petzl themselves produced the Ariane, a modern-looking plastic (though still robust) unit, which some users like, but is not rated at all by other users. A terrific more modern unit, was a self-pressuring work of art in stainless steel. Because it is self-pressuring, gas isn't wasted by bubbling away through the water reservoir as with other units. Once adjusted properly, you can get a great deal longer out of one fill of carbide. However it does tend to go berserk if too much water is added!

Various headsets can be chosen, Petzl being probably the most popular, though not necessarily the best. Petzl produce a burner-only model, and a combined burner with electric back-up - both with piezo electric ignition. The electric backup is frankly a bit ropey, so a separate small headlight (eg an LED unit, such as one of Petzl's) is a better option. The peizo ignition is really excellent and very reliable for a long time. The reflector is too small so wastes a lot of the potential light compared to some of the more agricultural wok-like reflectors on some other units which occasionally seen. Unfortunately none of the others has anything like as good a lighter as Petzl's piezo system. Perhaps some hybrid could be contrived with the Petzl lighter but a bigger reflector?

Most users make various small modifications to their lamps: popular tweaks include substituting a nylon mesh (ball-type) pan-scourer for the supplied filter, fixing on the hose with proper jubilee clips, etc.

An essential adjunct to the carbide lamp is the "pig" for carrying carbide, consisting of a length of (ideally Land-Rover) inner-tube, which can be sealed up each end with further loops of inner tube twisted over. A further loop is used to divide the pig in the middle so that spend carbide can be carried out of the cave in one half, with fresh carbide in the other. Alternatively a 2nd pig can be taken to carry the dregs out which simplifies things and avoids risk of dampness contaminating the fresh carbide.

It shouldn't need to be stated here, but carbide dregs (Ca(OH)2) should always be carried out of the cave and not dumped. As well as being unsightly, it is toxic to cave life, smelly, and generally unpleasant and unnecessary. Sadly in less enlightened times, carbide got a bad reputation due to irresponsible people dumping it in caves, and hence is banned from many systems. A trip to any of the classic European systems will show the worst excesses of dumping, with quite literally tonnes of carbide dumped in the Berger for example.

Even for expedition caving, various long-duration LED-based lamps are taking over, though they do not give anywhere near as good a light as an expedition carbide, nor provide the warmth much less the companionship if a hissing lamp. However they do require far less faff and are more reliable. Sufficient spare (dry-cell or rechargeable) batteries can be carried to give enough duration for any conceivable trip with far less weight and hassle than the equivalent amount of carbide

Recently, calcium carbide has become rather more difficult to get, and is possibly not even being manufactured any longer (at least in any quantity). The demand for carbide was no doubt from some obscure industrial process rather than for caving or mining use in any case. Perhaps the era of caving with an acetylene lamps is coming to a close, once remaining stashes in people's sheds have all been used up. It will be much missed, especially once the faff factor has faded from memory.