Lighting a large fabrication shop.

[ricicle]

I especially like using 13A sockets for hard to access light fittings in factories etc.

Fit a 3A fuse in the plug on the fitting then if a ballast fails short circuit like they always do, you only lose the faulty fitting, rather than the whole row, or the whole installation.

We used to do it that way. It is handy because it also means you can plug them straight into the socket on your bench for testing and repair.

 

[SimonH2]

Does this still apply to 'modern' high frequency control gear with an electronic ballast?

My guess would be, probably not.

To start with, the frequency of the flashes will be very different, much higher - so it will affect higher speed events.

To put it in perspective, at 50Hz, there are 100 light and dark periods per second, or 6,000 per minute. To get the strobe effect and have something appear still, then you'd need something that was in the same place 6000 times per minute. That could be something rotating at 6000rpm, but equally, it could be something rotating more slowly - but with multiple points of symmetry, a saw blade is a prime example of that. Say you've got a 40 tooth circular saw, it only needs to be going 6000/40 = 150 rpm for it to move one tooth per flash. it can be going any multiple of that, and "a" tooth will be in the same place, just not the next tooth.

The classic example most people (above a certain age) are familiar with is the old "wagon wheels going backwards" effect on old films. As the wagon changes speed, you can often see an effect where the wheels appear to stop, go backwards, forwards, stop, and so on. So as it slows, it might go from (say) 4 spokes/frame and stationary, then appear to go backwards slowly (but speeding up), then at some point it jumps to being a bit fast for 3 spokes/frame (so going forwards but slowing), slows through stationary at 3 spokes/frame, then going backwards as it's below the speed for that, and so on through reducing numbers of spokes/frame.

If the electronic control gear were running at (say) 10kHz, then that's 100 times the frequency. So the minimum speed anything must be going would be 600,000 <somethings>/minute. So a 40 tooth blade would now need to run at 15,000 rpm to synchronise. In practice, alternate teeth are different, so it needs to run at twice that speed for the teeth to appear clear and stationary.

It is possible - especially with finer teeth blades.


Secondly, the different lights will be running asynchronously - so it's highly likely that as long as you have multiple lights illuminating an object, there will never be distinct bright and dark periods. So for that reason, I'd think it's highly unlikely you'd see any problems with them.

 

[Lectrician]

I especially like using 13A sockets for hard to access light fittings in factories etc.

Fit a 3A fuse in the plug on the fitting then if a ballast fails short circuit like they always do, you only lose the faulty fitting, rather than the whole row, or the whole installation.

We used to do it that way. It is handy because it also means you can plug them straight into the socket on your bench for testing and repair.

Although, particularly with Metal Halie, you will find the fuses blowing for no reason at all occasionally due to the switch on surge of the fitting.

I prefer to design a lighting system such that if a circuit fails you don't loose too many lights.

For example, recently we did some aisles in a warehouse with lighting trunking and 6ft twin fluorescents. We wired every other fitting on a different circuit, 15 fittings per row. Allowed for 50% illumination too.

In a cold store with the fittings surface mounted on the ceiling, cabled in a void above, we ran the circuits/conduit 90deg to the aisles, so if you lost a row, you lost just one fitting in each aisle.

 

[ricicle]

We would only fit the 3A fuses in fluorescent lights to preserve circuits.
Any of our buildings that had M/H fittings in would have 13A fuses in as they would be the last thing to go after any lighting MCB

 

[dhutch]

I especially like using 13A sockets for hard to access light fittings in factories etc.

These have got 13amp plugs on, which as said, has already become very usful to see which of has traveled less well, or was one of the two not functioning when taken down!

If there are issue with mounting the ballest of these things on its side? I assume not? Due the height of the ceiling it has been proposed that the center lights and the lights over the fixed machinary be hung conventionally but those down the lower side over the boats be mounted on the side sans-refector, with the bulb 6inchs below the white underside of the roof.


Daniel

 

[scousespark]

What would be the best type of lighting for a large fabrication shop or workshop?

A freind of mine owns a boat yard where they build narrowboats, there unit is around 120*60ft (26*18m) and currently poorly illuminated with around 10 6ft striplights. During summer its find as there are clear sections in the roof but its now coming round to winter when its gloomy at best.

In my mind it is toss up between mercury vapor fixtures or metal halide floodlights, although they have re-lit a large area at work with clusters of floresent tubes but my experience is limited so Im interested if there is anything else to consider, as well as how many lights would be needed and the best way to arrange them.


Daniel

Do you have the required insurance to cover this work, given you have stated in other posts that you are not an electriacin?

 

[dhutch]

I'm not installing them, just discussing the options for them, and latterly, finding a supply of used highbays.

Doing some googling it appears there are both side-mounted and base-up versions of the lamps, so maybe they would be less of a fan of being put on there side. The lamps are GE 'Kolorarcs' which appear to be MetalHilide lamps designed to go into (older) SON/MercuryVap fittings.

Untitled

• dhutch
• 12 Nov 2012
• 2

Daniel