Workshop Power Supply

[mantney]

Hello

I wish to run a power supply from the house to my workshop in the garden. The electricity meter is situated in a porch at the back of the house. The feed comes from this to a large fused breaker switch and from this switch there are 2 feeds, one going into the house to a consumer unit in the kitchen and the other feeding a light in the porch and a floodlight on the porch. I am presuming that this breaker is old fashioned and will need to be removed as it isn't going to accept another cable into it to feed the workshop.

I intend to have a consumer unit in the workshop supplying the lights, sockets, a 30amp supply for a small welder and a separate supply going down the garden for pond pumps and lighting.
The workshop is about 6 meters from the house and I intend to use 10mm 3 core armoured cable 10ft overhead.

I suppose that the primary question is - would the fused breaker in the porch be replaced with another consumer unit containing 3 switches i.e. one for the house, one for the porch lighting and another for the workshop?

A qualified electrician will be doing the wiring but I want to have an idea of what’s required, get all the bits ready and run the cables through myself.

I look forward to your comments.

 

[Taylortwocities]

My advice is not to buy any "bits" yourself.

Any electrician worth his salt will be best placed to advise you, having looked at the situation on site.

He is the one who will need to sign a certificate to say that he designed, installed and tested the works.

I guess you want to save some money. Better to get the spark on board now. Discuss what you can do re the grunt work. He'll be able to get materials cheaper than you can in any case.

In 9 times out of 10, when a customer has got his own materials, its either wrong, or incomplete. I then have great pleasure in addidg extra time to the bill to compensate for all the running around required.

By the way, what makes you think that 10mm 3 core armoured cable is correct? Are you planning to export the houses earth outside its equipotential zone? What is the supply type?

 

[mantney]

My advice is not to buy any "bits" yourself.

Any electrician worth his salt will be best placed to advise you, having looked at the situation on site.

He is the one who will need to sign a certificate to say that he designed, installed and tested the works.

I guess you want to save some money. Better to get the spark on board now. Discuss what you can do re the grunt work. He'll be able to get materials cheaper than you can in any case.

In 9 times out of 10, when a customer has got his own materials, its either wrong, or incomplete. I then have great pleasure in addidg extra time to the bill to compensate for all the running around required.

By the way, what makes you think that 10mm 3 core armoured cable is correct? Are you planning to export the houses earth outside its equipotential zone? What is the supply type?

Thanks TTC for the info. To answer your questions - the cable is a presumption, the workshop will be earthed and i don't know what type of supply it is.

Treating my question hypothetically - would the fused breaker in the porch be replaced with another consumer unit containing 3 switches i.e. one for the house, one for the porch lighting and another for the workshop?
Is this assumption correct?

Regards

 

[Taylortwocities]

Do not know.
It depends on what it is doing there, and what the size is of the feeds, main switch, size of DNO's fuse, earthing, etc. .

A picture MIGHT help, but nothing can replace a visit to site. There are way too many variables and what you need there will depend on a lot of things.

For instance. Why do you think that you need 3-core armoured cable?

Also. A 30amp welder. That may need some specify fusing decisions.

 

[dhutch]

A welder requiring a 30amp feed is not a small welder...

I've got a 160amp (output) Esab Inverter Mig, and that happily runs of a 13amp plug via an extension lead or two, as well as providing a very nice weld. Although interestingly next doors 135amp clarke welder pops plug fuses for fun if you turn it up to full.

Daniel

 

[ricicle]

A 30amp welder isnt not a small welder...

If you read the original post again the 30A refers to the primary supply not the welder secondary current.....

 

[ericmark]

You are right in picking up the welder supply. I am lead to believe some suppliers need notifying with welders but not found anything written down. I would guess it depends on if anyone complains.

The inrush can be a problem what is a major factor is type of welder. An inverter does seem to put less strain on the system than a plain transformer.

Often you need type C or D type MCB's which impacts on the earthing arrangement clearly not a DIY job.

To worry about what to do about the boxes in the house before the electrician arrives on site is pointless. Let him look at what is there first and give you a report on how he thinks you should proceed. It may be a case of testing the welder first. Also the size of MCB rather than full blown moulded breaker varies from manufacturer to manufacturer and he may need to fit an mini consumer unit with Henley block to be able to get a MCB to fit.

 

[Taylortwocities]

As you say, The MCB in the workshop may need to be C or even D curve because of inrush.

The CPD at the house end may need to be a BS88 fuse for the same reason.
So it won't be a matter of just bunging in an extra MCB in your mystery "large fused breaker switch".

Site survey, evaluation of loads, review of existing supply and characteristics, circuit design.
All things that cannot be done on an internet forum.

 

[RF Lighting]

Be careful in choosing your electrician too. If they don't mention any of the things that have been mentioned here, then I'd be wondering if they are up to the job.

This isn't your standard domestic job, and many of the so called electricians out there won't have a clue how to do the job properly.

 

[dhutch]

If you read the original post again the 30A refers to the primary supply not the welder secondary current.....

Yes, that is how i read it also, i have edited my post to make this more clear.