Cables in conduit

Emtpencil · Posted: Sun Aug 20, 2006 4:24 pm Post Subject: Cables in conduit

I plan to run 4mm singles through 25mm condiut, to supply 20 metalclad sockets, on a factory floor. All the sockets are on one wall ( 40M in length ). I plan to run two circuits, 10 sockets on each, to 2 x 32A breakers. The conduit has travelled around 6 brick columns. The first half of conduit will have 12 single runs of cable ! I feel that I am going to struggle, pulling the cables through. Perhaps the first circuit of ten sockets, could be run in 2.5mm singles, as the length of this first circuit is only 20M long. Any tips or suggestions ?

Adam_151 · Posted: Sun Aug 20, 2006 5:00 pm Post Subject:

Stop trying to shoehorn ring finals into this application and work out what size of cable you need for two 32A radials?, I'm guessing it'd probably be 4mm² and 6mm², use MK sockets in order to be able to terminate 6mm²

SparkyMarky · Posted: Sun Aug 20, 2006 8:59 pm Post Subject:

Or run the cables in galvanised steel trunking with 20mm steel conduit drops to the sockets. That's how we'd always install this type of thing in our factory. Slightly more work installing the containment (not much though) but gives a very neat job and makes it dead easy to modify the circuits in the future..

Lectrician · Posted: Mon Aug 21, 2006 7:27 am Post Subject:

yep - 2x2 galv trunking (or even consider going bigger), with pvc or galv drops to sockets.

Calc the circuit - 40m is a long way! I suspect the longest run will need 6mm!

Emtpencil · Posted: Mon Aug 21, 2006 9:12 am Post Subject: Cable in conduit

I thought that radial circuits were a thing of the past ?
Even though this would be a hell of lot easier, but would it be as safe as a ring circuit ???? ie current flow

Lectrician · Posted: Mon Aug 21, 2006 10:56 am Post Subject:

LMAO

I would never install a ring in an industrial environment.

And at the end of the day, current flow is current flow. Deciding which circuit is going to handle this won't make the current any more or less.

Emtpencil · Posted: Mon Aug 21, 2006 11:02 am Post Subject: Cable in conduit.

Hi Lectrician, thanks for the quick response.

Why would you not install a ring cicuit in an industrial enviroment ??

If you dont mind me asking ?

ban-all-sheds · Posted: Mon Aug 21, 2006 12:16 pm Post Subject: Re: Cable in conduit

Emtpencil wrote:

I thought that radial circuits were a thing of the past ?

Quite the opposite.

Quote:

Even though this would be a hell of lot easier, but would it be as safe as a ring circuit ???? ie current flow

Safer, of course.

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Emtpencil · Posted: Mon Aug 21, 2006 12:23 pm Post Subject: Cable in conduit.

Cheers Ban....

securespark · Posted: Mon Aug 21, 2006 12:40 pm Post Subject:

Are you within the 75m2 limit?

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Emtpencil · Posted: Mon Aug 21, 2006 12:42 pm Post Subject: Cables in conduit.

Yes, definatley within the 75m2 limit.

JohnD · Posted: Mon Aug 21, 2006 12:45 pm Post Subject: Re: Cable in conduit.

Emtpencil wrote:

Why would you not install a ring cicuit in an industrial enviroment ??

The UK ring circuit is such a tremendously wonderful invention that it is mostly used in houses (and small shops/offices).

One of the principles is that on one floor of a house you will want plenty of sockets, but almost all of these will be for low loads (TV, table lamp etc) and there is unlikely to be more than two heavy 3kW loads (fan heater, washing machine) in use at a time, and each heavy load will be occasional or intermittent.

In an industrial environment you can expect to have quite a lot of people, possibly wanting to connect lots of things, all of which may be in use for the entire working day, so the expectation that there will not be more than two big loads does not hold good any more.

However, in a domestic environment, with the splendid UK fused plug, I think it is an excellent solution.

Modern kitchens often have a tumble drier and dishwasher as well as a combi microwave and washing machine, so unless (like mine) your kitchen has a couple of radials for the big loads, it can be useful to install a separate kitchen ring so that there is still headroom for other appliances on the ground floor.

ban-all-sheds · Posted: Mon Aug 21, 2006 12:57 pm Post Subject: Re: Cable in conduit.

JohnD wrote:

The UK ring circuit is such a tremendously wonderful invention

No - it was a short term expedient kludge introduced at a time of a copper shortage and high material prices compared to labour costs which coincided with rapidly rising demands in houses and it enabled quick and dirty conversion of 16A radials to 30A rings.

It only complies with the regulations because of the special-case hoops they jump through.

They are harder to test and harder to safely extend.

As yourself these simple questions -

1) if they are so good, why don't other countries have them?

2) if they did not exist, and all we had ever had were radials, who in their right mind would ever propose introducing them?

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Emtpencil · Posted: Mon Aug 21, 2006 1:04 pm Post Subject: Cables in conduit.

Hello JohnD

Thanks for your reply, but I'm a little confused. Without appearing thick, & what you've stated in the last comment with people wanting to plug allsorts in during the working day ( diversity ) why is it permissible to install a radial instead of a ring ??
Believe me JohnD, it would be the answer to my prayers to install 2 x radial circuits, but I just need to understand why one method as suppose to the safer method ?

Emtpencil · Posted: Mon Aug 21, 2006 1:57 pm Post Subject: Cables in conduit.

Ban, thats the thing I like about you, you dont mince your words !

Straight to the point !!

Good on ya !