Help. Any electricians about?

[Welderpaul]

Evening.
Tasked with wiring in three phase sockets in me shop.
Have an incoming 3 phase supply, metered, then into a DB (Fuse board). Currently has a number of 3 phase breakers and single phase breakers in it. Off one of the single phase breakers is a fuse board to supply lights and general single phase sockets.
I want to add 16A and 32A 3 phase sockets for my machines:

Question 1. Does each socket need to be on an individual feed/spur from the fuseboard, or can they be looped like a household ring main?

Question 2. I have err... procurred a drum of 6mm 5 core SWA cable. Is 6mm big enough?

Question 3. Most of my kit is 3 phases and earth. I understand that three phases, neutral and earth is used when a 3 phase machine has something on it which is single phase (Therefore requires the neutral to create the potential difference between once phas eand neutral). Where does the neutral come from. Is there always a neutral in the main fuse board? Do i just put 4 pin or 5 pin sockets in?

Run out of questions for the moment. There will be more. I know a sparky but cant get in touch with him at the moment - and i need to get on with it. The plan is for me to do all the donkey work and he makes the final connection, tests and issues cert. That was i am only buying him the beers rather than paying two blokes for a day even on mate's rates it's sexpensive.
Thanks. WP.

 

[Wozzaaah]

Don't know the answer Paul but if you could errr...'procure' me a drum of 16mm 3 core or preferably 25mm 2 or 3 core swa I'd be eternally grateful and pay you a considerable amount of beer tokens.

 

[Welderpaul]

Don't know the answer Paul but if you could errr...'procure' me a drum of 16mm 3 core or preferably 25mm 2 or 3 core swa I'd be eternally grateful and pay you a considerable amount of beer tokens.

I had to spend all me favours to get that. What you doing with 25mm2?

 

[ian of fev]

hes proberbley doing what i used to do paul many years ago lol

 

[Rusty]

I had to spend all me favours to get that. What you doing with 25mm2?

Weighing it in

 

[rusty69bus]

http://en.wikipedia.org/wiki/Three-phase_electric_power

 

[rusty69bus]

click distribution board

 

[Welderpaul]

Hi paul,first off i would use your 3 ph CU as just that and wire your single phase in to a separate cu,Also if there is single ph there will be a neutral in the cu.
6mm is plenty for 32a sockets and can be wired in a ring with no problem also a radial with 6mm could be possible with not too long a run or outlets.

Not sure on your meaning on question 3 you would only supply a neutral where required and none of my welding machines need one! hope this helps. cheers..pete....

Thanks Pete. That helps. Wiring in radial would be better for me, probably have 4 32a sockets on each of the two radial circuits. Would only ever be 2 machines on the go at one time. - Sound ok?

 

[Wozzaaah]

I had to spend all me favours to get that. What you doing with 25mm2?

Trying to get enough juice down to my workshop to run that bloody great miller tig!! It's a long way from the house to the workshop .

Ian, what exactly were you doing many years ago??????

 

[Welderpaul]

Ian, what exactly were you doing many years ago??????

He was down the pit weighing in scrap copper!!! 6 inch at a time!

 

[Wozzaaah]

if it was 67m I'd have your hand off for it but unfortunately 6 or 7m won't even get me from the front of the house to the back .
The run is actually 58m.
Thanks anyway .

 

[Welderpaul]

if it was 67m I'd have your hand off for it but unfortunately 6 or 7m won't even get me from the front of the house to the back .
The run is actually 58m.
Thanks anyway .

I bought some three core 25mm2 when i moved my consumer unit in the house. I was trying to remember where i bought it from. Then i remembered....I swapped it for some fab work!
25mm2 sounds a lot, even for a run of that length...

 

[Wozzaaah]

I'd get away with 16mm but I'd like to use 25mm to reduce the volt-drop. As they say, in for a penny, in for a pound And as George Michael sang, "If you're gonna do it do it right" err....he also sang "do it with me" but I'd rather not

 

[piman]

Hello Paul.

"probably have 4 32a sockets on each of the two radial circuits".

Your problem here is that the circuit breaker size for a 6mm cable will be 40amp, so if you run two machines on the one radial, (assuming the machines are close to the 32 a rating of the socket, and why fit a 32 amp if they are not?) then you will trip the breaker.

If instead you ran the cables as a ring then a larger circuit breaker could be used.

The neutral is run by the supply authority and most 3 phase distribution boards have a neutral bar fitted. Some machines have a requirement for a neutral so 5 pin plugs and sockets are used.

Alec

 

[Welderpaul]

Hello Paul.

"probably have 4 32a sockets on each of the two radial circuits".

Your problem here is that the circuit breaker size for a 6mm cable will be 40amp, so if you run two machines on the one radial, (assuming the machines are close to the 32 a rating of the socket, and why fit a 32 amp if they are not?) then you will trip the breaker.

If instead you ran the cables as a ring then a larger circuit breaker could be used.

The neutral is run by the supply authority and most 3 phase distribution boards have a neutral bar fitted. Some machines have a requirement for a neutral so 5 pin plugs and sockets are used.

Alec

Thanks Alec, If it was run as a ring, what is the maximum size circuit breaker that could be used?

 

[ian of fev]

hi paul i was asking my mate at work today about your wireing problem he worked with me at the pit as a pit sparkey he was listning to what i was telling him and then he said 415 v is a little diferent to 11000 v transformed down to 6000 v still 3 phase though just a little diferent he said most of the electrical work he did was on transformers and substations a bit diferent to your situation but hey you never know where help comes from and i supose as your just starting up every little helps (sorry) he said if he had worked at the pit top in the workshops he may have been able to help as most of the pit top sparkeys are all sixth edition graded

 

[piman]

Hello Paul,

double it, say 80 amp.

Alec

 

[Welderpaul]

hi paul i was asking my mate at work today about your wireing problem he worked with me at the pit as a pit sparkey he was listning to what i was telling him and then he said 415 v is a little diferent to 11000 v transformed down to 6000 v still 3 phase though just a little diferent he said most of the electrical work he did was on transformers and substations a bit diferent to your situation but hey you never know where help comes from and i supose as your just starting up every little helps (sorry) he said if he had worked at the pit top in the workshops he may have been able to help as most of the pit top sparkeys are all sixth edition graded

Thanks Ian - appreciated!

 

[RichardFisher]

6mm armoured cable

Hi,
I desperately need to buy some 6mm armoured cable for tomorrow Sunday.
Can you help please?
I'm in Bath.
Thanks so much!
Best regards,
Richard Fisher
01225 443020
0779 5831576

 

[madkayaker]

Some three phase has a N to provide 230V single for control circuits etc. Motors don't require a N as it works on the PD across two phases witch gives you the 400V. Same as lots of 3PH welders are really 400V Single.