Swa size

[gazdkw82]

Friend of mine is having a feed to his shed.

Wants 5 sockets and some basic lighting. I think 40A would be sufficient.

its 20ft away max.

what size swa would you recommend?

Would 16mm be ok?

 

[Simonslimline]

What do your calculations say?

Based on actual Ib and not In.

 

[micknew]

35mm 4c core to be on the safe side.

 

[Dan the spark]

Have you checked the regs to see what the maximum current carrying capacity of 16mm SWA is?

 

[Wonderwall]

35mm 4c core to be on the safe side.

At the very least.
plus a separate 25 mm Earth wire just to be on the safe side.

 

[Dave OCD]

Come on the OP is a trainee, the posts above are hardly productive ?

 

[Deleted member 72666]

It's not a job you should be considering.

 

[Dan the spark]

The regs are there to help you out in this situation. Have a look at the current carrying capacities of SWA, installation method comes into play and also volt drop. I'd say that if its 20feet max then your not going to notice much volt drop but just to 'cross the Ts and dot the i's'.

 

[micknew]

Come on the OP is a trainee, the posts above are hardly productive ?

Perhaps it should be in the trainee or DIY section?

 

[davesparks]

Friend of mine is having a feed to his shed.

Wants 5 sockets and some basic lighting. I think 40A would be sufficient.

its 20ft away max.

what size swa would you recommend?

Would 16mm be ok?

Could you tell us what calculations you did to get arrive at 40A and 16mm, then we will be able to help you understand where your calculations may be going a bit wonky.

If you are a trainee as mentioned above then it would be best to ask your questions in the trainee section where you won't get any of the **** taking which has occurred in this thread.

To be honest you would be better off ask the electrician Ho is mentoring you through your apprenticeship for help, and also to advise you on when you are ready to start doing little jobs like this on your own.

 

[davesparks]

Is their not a forum trainee or DIY section?

There is, and hopefully the OP will now post there in the future

 

[davesparks]

The regs are there to help you out in this situation. Have a look at the current carrying capacities of SWA, installation method comes into play and also volt drop. I'd say that if its 20feet max then your not going to notice much volt drop but just to 'cross the Ts and dot the i's'.

The current carrying capacity tables are no use until a figure of In which has been adjusted according to correction factors has Ben established

 

[Dan the spark]

The current carrying capacity tables are no use until a figure of In which has been adjusted according to correction factors has Ben established

I thought op had already worked out In as they stated the value of 40amps

 

[gazdkw82]

Sorry for late reply. Battery died

I should have explained. i was given this information from a friend of mine who is doing the job, I'm just helping and watching really. I was just thinking out loud and wanted to know what size swa would be needed. He probably knows already but I wanted to see if I could figure it out myself.

i guess I would need more information to really work it out

 

[micknew]

Sorry for late reply. Battery died

I should have explained. i was given this information from a friend of mine who is doing the job, I'm just helping and watching really. I was just thinking out loud and wanted to know what size swa would be needed. He probably knows already but I wanted to see if I could figure it out myself.

i guess I would need more information to really work it out

If he only 'probably knows' he shouldn't be doing the job.

 

[Wonderwall]

Come on the OP is a trainee, the posts above are hardly productive ?

You are spot on. I was only joking. In the real world a 6mm swa will suffice for a long long long time .

truth be told a 2.5 wouldn't come to any harm either. There is never likely to be any substained load on this cable

 

[micknew]

you are spot on. I was only joking. In the real world a 6mm swa will suffice for a long long long time .

Truth be told a 2.5 wouldn't come to any harm either. There is never likely to be any substained load on this cable

wow .

 

[davesparks]

I thought op had already worked out In as they stated the value of 40amps

The chances of the application of all factors resulting in a value of 40A is pretty unlikely don't you think?

 

[Dan the spark]

The chances of the application of all factors resulting in a value of 40A is pretty unlikely don't you think?

It's a shed with '5 sockets in and some basic lighting', op didn't state they were going to be running a machine shop out of it. I understand where your coming from. Obviously if he would have said what he was intending on using the shed for and then listed in detail every piece of equipment that his friend would be using then I would have been happy to point him in the right direction as to what size cable he should be installing. But instead I pointed out that maybe using the In value that he imo had possibly sat and worked out (seeing as it's only 5 sockets I'd have said he had no intention of pulling 40amps) he could look at the tables in the regs and then come to a conclusion for himself and then possibly come back and show how he come to his decision and then we could help out from there.

 

[Lucien Nunes]

i guess I would need more information to really work it out

Yes-ish, you can take an educated guess at the kinds of load and do a sanity check. 40A you say. 40x230=9200W. What might be used in a shed?
Fanheater 2kW
Freezer 150W
Dehumidifier 300W
Two double florries (nice and bright) 300W
Chunky power tool 800W with...
Dust extractor 800W
Two tool chargers 300W
Other half mowing the lawn 1200W
Laptop 100W
Stereo turned up loud 100W...
I'm starting to run out of realistic ideas and we're only at 6kW yet with everything on at once, and fanheaters and lawn-mowing don't often go together.

6050/230=26A, call it 30A to allow for pf<1 e.g. on the motors. What cable do we need for that? Look up the CCC for 2.5mm² XLPE SWA as per WW's suggestion and under most conditions you'll find it's in (voltage drop to be considered as well of course). 4.0 or 6.0 gives a healthy margin.

As it happens my shed IS fed by 4x25mm²...

 

[davesparks]

It's a shed with '5 sockets in and some basic lighting', op didn't state they were going to be running a machine shop out of it. I understand where your coming from. Obviously if he would have said what he was intending on using the shed for and then listed in detail every piece of equipment that his friend would be using then I would have been happy to point him in the right direction as to what size cable he should be installing. But instead I pointed out that maybe using the In value that he imo had possibly sat and worked out (seeing as it's only 5 sockets I'd have said he had no intention of pulling 40amps) he could look at the tables in the regs and then come to a conclusion for himself and then possibly come back and show how he come to his decision and then we could help out from there.

Yes, but he is a trainee, so it would be far better to help him understand the proper process and calculation rather than suggesting shortcuts without a proper explanation.

Any experienced electrician will be able to size this cable without any calculation just by a rule of thumb, but it is wrong to suggest to a trainee that they should select cable sizes in this manner

 

[Wonderwall]

wow .

You learn something everyday. Are you telling me 6 mill swa won't carry this load for 20 metres?

 

[Dan the spark]

I haven't suggested taking any short cuts. only shortcut I know is the one to the beer fridge

 

[Pete999]

Come on the OP is a trainee, the posts above are hardly productive ?

Likewise

 

[Pete999]

OP get yourself permission to join the Trainee section, reasons why? as a trainee you need advice not p=sstaking as in some of the posts in this thread. Some of the replies have intimated that perhaps you shouldn't be taking on a job like this on your own, which realistically is correct.

To ask a question "what size SWA do I need" lays you open to abuse, which as a Trainee can be detrimental to your training. There are lots of things you need to do before start choosing the size of cable, Installation method, applying all the correction factors, what is the point of origin of the supply, what type of supply, what is the likely hood of any extraneous metalwork in the "Shed" etc etc.

Do you have anyone mentoring you? ask for advice, I'm not having a dig at you, it's the best way to learn by asking, get into the Trainee forum, and ask again with some more details, show what calcs you have done and how you intend to get this job done, with supervision, you will get more help that way, and less abuse.

 

[gazdkw82]

I didn't mean to cause all this bother :-/

like i said my friend basically asked me if I wanted to tag along for some experience. I have no doubt he has worked it out. But the one thing he didn't tell me was the size of the swa cable and it got me thinking which is why I asked.

ultimatly i I don't have enough information to work it out so I'll have to ask him

 

[Pete999]

I didn't mean to cause all this bother :-/

like i said my friend basically asked me if I wanted to tag along for some experience. I have no doubt he has worked it out. But the one thing he didn't tell me was the size of the swa cable and it got me thinking which is why I asked.

ultimatly i I don't have enough information to work it out so I'll have to ask him

Well there you go, ask him how he arrived at the size of cable he is using, is he an Electrician or just a mate DIYer hoping you will be able to put him right?

 

[gazdkw82]

He's an electrician. I will ask him when I see him.

apologies, I didn't mean to be a noisance. I just think about all these things a lot and it just crossed my mind about the size of swa cable so thought I'd ask.

thanks for the words of advice. I already have access to the trainee section. This should have been posted in there

 

[Pete999]

He's an electrician. I will ask him when I see him.

apologies, I didn't mean to be a noisance. I just think about all these things a lot and it just crossed my mind about the size of swa cable so thought I'd ask.

thanks for the words of advice. I already have access to the trainee section. This should have been posted in there

Mate you aint being a nuisance, honest, good luck and ask one of the Moderators for Trainee status. you'll learn nothing if you don't ask.

 

[gazdkw82]

Mate you aint being a nuisance, honest, good luck and ask one of the Moderators for Trainee status. you'll learn nothing if you don't ask.

Trainee status?

 

[Pete999]

Trainee status?

Access to the Trainee section,

 

[gazdkw82]

I already have access I believe

 

[Pete999]

OK didn't realise, sorry, you did post this in the general section though.

 

[gazdkw82]

Sorry :-/

really appreciate the advice

 

[Pete999]

Sorry :-/

really appreciate the advice

You're welcome

 

[telectrix]

Sorry :-/

really appreciate the advice

never be afraid to ask. itis the duty on experienced sparks to pass on their knowledge to trainees and apprentices. while hands-on face to face is the best way to learn, advice from this forum is a fair substitute. the main drawback with internet is the fact that you can't get a scuff round the ears for getting it wrong. :rofl:

 

[Deleted member 72666]

I didn't mean to cause all this bother :-/

like i said my friend basically asked me if I wanted to tag along for some experience. I have no doubt he has worked it out. But the one thing he didn't tell me was the size of the swa cable and it got me thinking which is why I asked.

ultimatly i I don't have enough information to work it out so I'll have to ask him

You say the one thing your friend didn't tell you was the size of the cable, did he then tell you what the shed was to be used for and what the sockets were likely to supply, after all he's arrived at a value of 40amps. More info is definitely required as this installation might not be the 'run of the mill' garden shed, just saying.