How much light for a garage?

[The Natural Philosopher]

Mmm. I wonder if that's what I have.

[John Rumm]

IMBW but I was under the impression that modern fl lights had high frequency ballasts to eliminate this problem? I must admit to never having observed the effect myself in my workshop which is all fl lighting and I am usually very sensitive to flicker (find 50Hz TV quite objectionable for example).

Then again I can usually tell when a tool is running due to the noise!

[John Rumm]

Something else I forgot mention - it is well worth going for a fitting that has a nice tight fitting diffuser. Not only will this make the light nicer to work in, and keep the dust of the tubes, but more importantly it has saved a tube on a number of occasions when I have been rotating a large bit of stock and forgot that it was longer than the height of the lights!

[Andy Hall]

You would know from the price tag and the weight.......

Generally you specifically have to ask at electrical wholesalers for electronic ballast fittings or they assume that you just want the cheap choke versions.

.andy

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[ARWadsworth]

Profit making SOBs how dare they do this?

The other advantage of putting a bulk head light over the workbench/pasting table/B&D workmate is that for the £3 it takes to fit you get a light in front of you not behind you.

-- Adam

adamwadsworth@(REMOVETHIS)blueyonder.co.uk

[usenet]

They are getting a lot cheaper now though, I just bought some 5ft fittings with electronic ballast for £11.75 (I think it was) from Denmans.

[Andrew May]

Or investigate replacing the ballasts in the fluorescents with electronic ballasts that have a much higher operating frequency so don't show this effect.

Of course if you are using machinery then you might also want to consider some form of emergency lighting so that if the power goes off you are not left in the dark with a still spinning blade nearby.

I am going through this process at the moment. Can anyone point me in the direction of some form of UPS for lighting so that it will all stay on? Only needs to be for ten minutes or so. Non-maintained bulkheads are cheap enough but I would rather trade light output for time.

Andrew

[Andy Hall]

I've done this, but realised later that it's more expensive than just replacing the entire fitting.

I looked at this too, but couldn't find one. In the end I found that WF Electrical had own-brand 55w fittings, maintained, with protective covers for under £100 before discount.

I put two of them spaced out among regular fittings on the ceiling of the workshop and a small 8W one near the door. This is plenty to cover the safety aspects.

I couldn't find a UPS with reasonable power output at this sort of price. Those intended for IT purposes are short duration, higher power but cost more......

.andy

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[Rich]

Thanks for all the suggestions.

I hadn't thought of a bulkhead light as well as strips - good plan. And despite watching all those property programmes, I hadn't thought to paint the walls white either.

Screwfix beckons...

RE: separate light switching. I was planning on using a pull-cord for the lights. Is there such a thing as a 'pull once for light A, twice for light B, thrice for lights A+B and four times for lights off' pull switch.

And for that matter, has anyone got any tales, good or bad, about the Screwfix Garage Consumer Unit? Its a 40A RCD unit with two (6A and

16A) MCBs. I gather there might be some discrimination problems connecting it to my house CU (via a spare fuseway) which is itself RCD-protected. Effectively, the garage circuits would be protected by their MCBs, the RCD in the garage consumer unit, the MCB in the house CU, and the RCD in the house CU.

[Andy Hall]

You could implement this with impulse relays, but it would not be a cheap option.

Is that enough or are you sure it will be enough for future requirements.

There is no discrimination in this if the RCDs are all of the same type, so what then trips out will be arbitrary. You may not want this.

.andy

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[PoP]

I've got a similar model in my garage (not identical) with 2 RCD protected circuits - 6A and 16A.

I just got thru wiring an electric fan heater in there today. Being a

3KW jobbie it's going to pull some 12A when operational. That leaves 4A or about 1KW before the RCD pops its clogs, which will compromise some of my power tools!

Haven't thought about this problem before (I have to admit I assumed it would be a 30A supply). I'm wondering whether a solution is as simple as uprating the RCD, or am I going to have to consider other alternatives?

Garage is fed from an armoured cable from the house - I'll have to check this further to make sure of capacity but it looks to me to be beefy enough to handle a higher load. I know the armoured cable comes thru the house consumer unit 100A RCD because (with the circuit RCD switched off) the 100A RCD tripped the house out when I chopped thru the mains cable in the garage - presumably due to some small current flowing between live and earth even with the circuit off.

PoP

[stefek.zaba]

No, the live was isolated. But the neutral wasn't (single-pole breaker, neutrals commoned on the RCD side). When you chopped through the cable, you gave the current flowing back to the neutral block and back to the balance-detection circuitry of the RCD another path back to earth (through the N conductor of the SWA and back down the earth conductor). Doesn't take much of an imbalance to make the RCD pop, right?

(This comes up often enough that Someone ought to write it up for the FAQ under "why does my RCD pop when I've disconnected a circuit with the MCB?"...)

Stefek

[usenet]

You've got your RCDs and MCBs confused, I think.

The 6 amp and 16 amp rated things in your garage CU are MCBs, that is they're overcurrent devices. Hopefully there is *also* an RCD protecting at least the 16 amp sockets circuit. The usual arrangement is that the incomer switch device on the mini CU is an RCD (rated at

30mA trip current) which feeds the two MCBs. (A less likely possibility is that you have RCBOs, combined RCD/MCB devices)

One fairly simple approach would be to uprate the 16A MCB to a 20A one, this would be 'correct' for a radial circuit wired in 2.5sq mm feeding sockets. This would give 8 amps or so 'headroom' for your machinery. As long as the feed from the house is also at least 2.5sq mm and isn't too long then this strikes me as the obvious solution.

It would be touching neutral to earth that tripped the house RCD.

[PoP]

Thanks for explaining. I did wonder!

And there was me thinking I must have been charged up with static.....

PoP

[N. Thornton]

Hi

Theres another solution to flicker other than en electronic ballast. That is to have 2 lights close by, or in same fitting, with one fed thru a series capacitor. This shifts the phase of one of the lights and gets rid of most of the flicker. Result is the optical illusion problem is gone. The other traditional solution is to have an incandescent worklight over each lathe etc, as well as th general fl lighting.

Regards, NT

[Andrew Mawson]

Surely it isn't the phase that is a problem - shifting the phase will only move the 'frozen image' round the circle of rotation. The problem is that the frequency is or is close to a multiple or sub multiple of the rotational speed. (If close then the frozen image will progress slowly)

[Christian McArdle]

But if you have two lights, with the phase rotated 90 degrees, you'll find that as one light fades out, the other is just coming in. This is similar to why a 6 cylinder car engine is smoother than a 4 cylinder one.

Christian.

[The Natural Philosopher]

Sadly phases are not no dgerees out of phase, but 120.

A three tube three ballast three phase light fitting would be better, but an elelctronic ballast is - er - cheaper?

>

[Andy Hall]

and will facilitate the light firing up quickly and brightly when it's cold........

.andy

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[N. Thornton]

What happens with these 2 tube setups is that one runs out of phase to the other one, and the light from the 2 add. The result is that you get light output for the majority of the cycle, thus the frozen image is no longer frozen, it is a safe blur instead.

Regards, NT