Excess Lighting Cable wound round on Lighting Bars

[paulears]

I have to say I'd never taken the heating effects verys seriously, until I tried to unwind a pvc extension cable drum that had had a few movers plugged into it for no more than 3 months. It wouldn't unwind, so I heaved and the drum broke apart, revealing a melted mess of blue pvc, odd bare conductors and yuk!

 

Never again, but in the past I'd got away with it........

[bruce]

.....after all they are always saying:

We are the least payed department it school, therefor the supplies and equipment is limited.

I suppose that it would mean getting up the ladders and taking down the cable, unconnecting the ends, cutting it down, refitting the ends, then get 2 new connectors and connect them to the cable. And there you go, 2 cables, they make it seam like it will take a lifetime, when its a 30min job.

 

Rich

 

... or maybe they are more qualified and experienced than you to decide whether it's cost effective for them to do the job.

 

Calling this a "30 min job" is only realistic if all of the tools and equipment required are close at hand. A more realistic timescale - getting to the job, getting out ladders etc, doing the job, PAT testing, documenting, putting things back the way they were, putting the ladders away etc - would be ( very conservatively) around an hour.

 

And don't forget that both "ends" of the job involve ladders, so it's a 2-person job.

 

So this "simple, cheap" job actually costs at least 2 man-hours work.

 

Now, I've no idea who the people doing this job would be, but I'm guessing it's a school/technician environment. Let's assume they're getting paid around 20k per annum. That means that the cost to the employer to employ these people is roughly 20 pounds per hour.

 

So. Assume they did the job. It would cost the organisation 40 pounds, and at the end of the day the organisation has gained.... ummm... a bit of old cable. Hardly cost-effective.

 

By all means argue that jobs like this should be done for H&S reasons, or neatness, or whatever. But arguing that they should do it "because that department is so badly off" is rather naive.

 

Sorry if I appear to be ranting, but at work I'm constantly having to justify installation costs to people who assume that it "only costs pennies" to screw something to the wall.

 

Bruce.

 

edit: speelung mistooks.

[Ekij]

Be very careful coiling cables that have high currents running through them.

Make sure there is an air gap for the heat to dissipate or you could end up with this ....

http://www.btinternet.com/~boxzone/Other/C...tensionLead.htm

[d_korman]

The heating effect of the coiled cable is to do with the reduced heat dissipation when the cables are close together. Much like you have to derate cables in a domestic installation if you bunch them togther into the consumer unit. Lamost all the heat generated is a result of resistive loss in the cables.

 

The inductance effects are negligible - you have two conductors close together carrying equal currents in opposite directions - net magnetic field is or is very close to zero so no induction.

[Tomo]

Calling this a "30 min job" is only realistic if all of the tools and equipment required are close at hand. A more realistic timescale - getting to the job, getting out ladders etc, doing the job, PAT testing, documenting, putting things back the way they were, putting the ladders away etc - would be ( very conservatively) around an hour.

<snip>

So this "simple, cheap" job actually costs at least 2 man-hours work.

<sniP

So. Assume they did the job. It would cost the organisation 40 pounds, and at the end of the day the organisation has gained.... ummm... a bit of old cable.

Unfortunately, in a lot of organisations it would be the only way to get a length of cable.

 

For example, the cruiseline I work for seems to consider 'man-hours' to be free, and consistently refuses to invest in equipment that would save a great deal of time for not a lot of money.

On several of the ships there are people who spend maybe 90% of their time moving CABLES from one venue to another. The cost of having enough XLR, jacks and power cable to do the events without moving these would pay for itself in one, maybe two days, not to mention the improved reliability of not having to plan the entire day in terms of cable motion.

 

Other shortages (parts of drum kits, keyboards etc) would pay for themselves in under two months.

 

The reason appears to be that wages come from a different budget to capital expenditure, and accountancy departments have a great deal of trouble with the concept that money spent in one budget will reduce expenditure in a different budget.

 

Just my tuppence-worth.

[Bryson]

Interesting, Tomo. I had a very different experience with budgets that were very, very forgiving. The only bizarre thing was that buying 2 bits of XLR was a problem, but replacing every cable on the ship wasn't....

 

Perhaps we should continue this via PM?

[Just Some Bloke]

Now, I've no idea who the people doing this job would be, but I'm guessing it's a school/technician environment. Let's assume they're getting paid around 20k per annum. That means that the cost to the employer to employ these people is roughly 20 pounds per hour.

 

So. Assume they did the job. It would cost the organisation 40 pounds, and at the end of the day the organisation has gained.... ummm... a bit of old cable. Hardly cost-effective.

 

Or look at it this way:

 

They don't do the job - they get paid £20k per annum

They do do the job - they get paid £20k per annum

Extra cost in man hours for doing the job - £0.00

 

Result - extra extension lead for the cost of a plug and socket, plus H&S improvement.

[AndrewR]

off topic.

 

I suspect that tomo is working for someone other than princess! The company I worked for (in the caribbean and a bit... royal) had a similar attitude towards new equipment. I spent lots of time moving equipment and cables! That and waiting 6 months or more for replacement parts for movers.