32a 3 phase extension lead.

[Robo]

My dad wants me to make him an extension lead. Currently a 32A 3 phases soscket on a genrator. He has severral different loads ( all motors) but there total loads are about 20A

Use some braided SY cable. 4mm 4core or 5 core? I guess its better to have a seprate earth core so 5 core.I need to calc maximum length, what table would i use in BIG RED BOOK??

I was then going to go to an adaptable box and have 3 32 a sockets. Do i need to fit isolation switch to each one if any or is it ok not to have any as its an extension lead.

 

[bugsy]

I would not under any circumstances install 3 phase extension leads ,

 

[Engineer54]

My first thought is why does he need extension leads?? If he has a 3ph Genny, why are these motors not connected so to speak permanently, well via sockets outlet that are permanently installed?? Most motors require a motor stater with suitable overload protection...

What usage and where are these motors and Genny?? It would be better if you gave us more information, to be able better to advise you on the best course of action.

 

[Hawk81]

I would not under any circumstances install 3 phase extension leads ,

Can you tell us why?

 

[Knobhead]

5C braided cable
But for gods sake get the phase rotation right! I’ve seen more cock up’s with wrong phasing than I care to remember!

 

[nickblake]

Yes some SY Cable but make it as a proper extension using 5 cores ,so you have L1,L2,L3 ,N CPC , an personally i would go for 6mm ,

 

[Steve1412]

Cant see any problem in using extension leads??? Have used them on all sorts of applications even upto 125amp........you could knock a bull out with one of those plugs.lol

 

[Robo]

The generator only has 2 32a plugs i think. So he wants the extension lead to power 3 smaller items and use the other spare socket for a larger load. The items to be plugged in are a compressor, baging machine and electric roller door. Total load about 20a.

SO

i would like to make an extension lead with 3 32 sockets on the end. I was going to put a 5c 4mm or 6mm sy cable with red 5 pin plug on 1 end and then go to adaptable box and split to the 3 32 a sockets. Is this ok?? Do i need a inline isolator or individual isolator?? Any help would be much appreciated

 

[Engineer54]

Robo,

I don't know if this is for your dad's garage, or for his place of business, but either way (especially if it's his place of business) All those loads sound to me as ''Fixed'' or permanently placed bits of kit, and as such shouldn't be supplied by extension leads, but wired in as a permanent installation. If it is your dad's place of business then he could get into some serious trouble with the HSA/Local Authorities etc.
All those loads will need a local isolator, and i'm assuming that each of those motor loads already have overload protection within there equipment control boxes.

It's not a big or complicated job, to wire these items up individually from a small 3ph DB, and a lot safer too, than having a permanent trip hazard with these proposed extension leads. Really only portable equipment should be supplied by extension leads, ....ie, ...being used and then put away.

 

[Robo]

Enginner 54,

Its a place of business so has to be right. It has a 125a 3p supplyto building currently. However no 3p distribution. There are likely to be more machinery etc in the future. exceeding the 125a supply and would need a larger supply. ( mega bucks according to the sparky whos looked at the job). So the company wanted to opt for buying a larger generator. Which could be moved around. And the machinery also moved around, hence his requiredment for extension leads. He wants to do it properly and as safe as can be just the generator seems to be the way they are goin. Should i suggest a 3 phase install hardwired around the shed and connect that to the genny. ?? thanks

 

[Robo]

I asume all the loads have overlaod protection as there new kit. And other than the door there all potable, on wheels or lifted with fork truck.

 

[Engineer54]

That would be the way to go Robo.

125A 3ph supply is a pretty reasonable supply to have, don't forget a lot of those loads won't all be on at the same time, or be short duration . Really needs someone with experience to do a survey of max demand/diversity on the existing and the proposed future machinery.

Generators can be an expensive choice of power mate. Also consider that generators of any substantial size need to be loaded at a minimum of 60 to 70%, or they tend to end up destroying themselves. One of the reasons why many Gennie's need to be connected to load banks, also expensive especially if automated.

The price you'll be paying for a Gennie to supply in-excess of 125A as a prime power provider can also be expensive, then you have to think about continual on-going maintenance and replacement parts, as well as feeding them copious amounts of fuel....lol!! ...And when they do go wrong, loss of production!!!

Best bet all round in the long run, is a DNO power supply. But whatever way he chooses he needs the electrical installation to be hardwired to satisfy the authorities....

By the way, machinery that requires a fork lift to move them around tend to be classified as ''Fixed'' ...haha!!!

 

[Robo]

Iv told him to get some1 there, sort the job out and certificate it all .Every1s happy. Thanks for your help.

 

[wymondhamcables]

I see this is an old post but H07RNF rubber flex would be my choice of cable

 

[Spoon]

I see this is an old post but H07RNF rubber flex would be my choice of cable

Just a bit old mate.... It's great that you are contributing, which is more than some do.