Linking multiple Sub DBs

**Isetech** · 08-Jul-22, 08:10 PM

I am looking for a quick cheap solution.

I have 1 building partitioned into 10 sections and each shop must have a ready board prepaid meter installed.

My plan is to run a cable from the main DB in different building to a sub DB on one side of the building. Then run a 16 mm cable from a 60 amp mcb to a junction box below a ready board, join the the 16 mm wires and fit a tail from the junction box up into the ready board main switch out to a pre paid meter and into the ready board. Maybe fit a 20 or 30 amp mcb before the main switch in each ready board.

The cable to each junction box and up to the ready board will be 16 mm cable, protected by the 60 amp breaker in the sub DB,

I have also considered fitting a 6 way DB below the ready board with a 20 or 30 amp breaker, but that would just create more cost.

**Dylboy** · 09-Jul-22, 09:09 AM

I think your plan is good!

The junction box, joint 16mm into a 3 point join us tricky,

Look I have never had to do it with big cables so not sure how best to do it.

The junction box must just be accessible which I am sure you know but that is about all I can think.

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**Isetech** · 09-Jul-22, 09:46 AM

One concern is the location of the sub DB, this DB must be accessible to anyone who needs to isolate the feed to each shop. I was going to install it inside one of the shops, but that could cause a problem for accessibility. I am thinking rather fit it on the back wall so that anyone on the property has access. You can isolate the power at the meter box, but not everyone has a key to the meter box.

**Dylboy** · 09-Jul-22, 10:17 AM

What about seperate supplies from sub DB to each unit, say then only a 10mm cable needed and a 30Amp feed ? Then each stand can have it's own feed cut off when needed for cable repair and then each ready board to isolate any final circuits in the stand ?

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**Isetech** · 09-Jul-22, 10:33 AM

Originally Posted by Dylboy

What about seperate supplies from sub DB to each unit, say then only a 10mm cable needed and a 30Amp feed ? Then each stand can have it's own feed cut off when needed for cable repair and then each ready board to isolate any final circuits in the stand ?

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Cost, we have a tight budget.

**Dylboy** · 09-Jul-22, 12:02 PM

Look I think then your plan is good. The ready board can isolate those circuits and it's not often the feed needs Isolating so that is fine.

Also if that is the budget then that is what it is.

You can make it as practical as possible for the budget and if they want it proper then pay it.

VW money for a Ferrari is not possible.

It's hard as we want the best job we can do but if the budget is set then it's set. It's sad but that is life

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**Isetech** · 09-Jul-22, 12:47 PM

Generally I would have run a main cable to the shop building, then installed 10 mcb's and run the correct size cable to each ready board. 10 mcb's mean a bigger DB, more money on mcbs, 10 cables and a wire way, more money.

For this particular job it makes sense to run one cable to the junction box and so long as the tail into the main switch of the ready board is the same size I cant see a problem.

The shop building will have a 60 amp single phase mcb which will be in the main DB (shop building DB) which will be accessible to any of the shop tenants.

There will be a main switch in each ready board which can isolate all the power to the shop it supplies.

The ready board will also be fitted with an ELU, 1 x plug circuit and 1 x light circuit.

Security lights etc will be fed from the shop building DB.

Another way I could do it, run the cable and fit a double pole isolator in each shop, then up from the isolator into the ready board. I could use those cheap cheap weather proof ones that we use outside for AC units.

**Derlyn** · 09-Jul-22, 02:27 PM

Couple of years ago.
11 rooms each with prepaid meter and ready box.
No frills.
Main DB at end of building with a 60Amp supply for all the rooms.
10mm cable with camera box and line taps well insulated.
10mm FTE to each meter and ready box.
Klaar gelag ( no frills )