Another Shed / Workshop / Home Office

[Gillingham]

Hi

We will be building a 20' x 10' workshop/office at the bottom of the garden and want to run up electrics from the main fuse box. We'll be getting internet/phone run up as well so are looking at a largeish underground conduit from house to shed. We will be getting a sparky in to do work and have it Part P certified. But we want to cost up or source (ebay spares?) materials before getting a quote but not sure what the electrical specification/search terms are to google. Can anyone give us spec phrases to use please?

The workshop will:

• be up to 40m away from house with main CU a further 5m away
• have 2 light fittings (probably 2 x twin flourescent tubes unless anyone recommend something else?)
• have up to 8 double sockets (for convenience rather than use!)
• In the middle of winter circa 21:00 I will have at most an electric heater on, a computer, another computer monitor, a TV or radio, both sets of lights, my mobile charging up and a kettle ; &gt

1. What is the spec for a 2 or 3 circuit CU in the workshop?
2. What is the spec for the armoured cable running from the house?
3. What is the spec for the cabling inside the workshop?
4. Is there any minimum spec for the socket back boxes and face plates or can I just go for the cheapest?

Thanks in advance for all assistance.

 

[ProDave]

You are setting off on the wrong foot with this one.

You clearly want to source the materials yourself which must mean you are expecting your electrician to be over charging you for the parts?  If that's your starting point, expect a frosty reception when you start talking to electricians.  Most of us only charge a modest mark up on materials supplied and we can often buy them from wholesalers at trade prices so cheaper to start with.

And then add into the mix if what you buy is wrong, or just rubbish quality who pays for the wasted time putting it right or halting the job while you source more materials?

Where you CAN save a lot of money without upsetting anybody is to to all the digging to get the trench from the house to the workshop, and prepare access etc to get a cable route from the house CU to the outside.  then my agreement with the electrician doing the job pull in some of the cables to the route and specification he gives you.

It will need at least 2 ducts in the trench for separation between mains supply and telecoms etc.

 

[kerching]

I will not as a rule install,customer supplied materials....unless it is the hi end comms/data stuff

Fittings and accessories are usually the lowest of the low,,cable is nearly always carp and the wrong size "the bloke in the Shed said it was near enough the right stuff AND he had an orange apron on, so he MUST be right"

Just....been there, done that

 

[Lurch]

Step 1 is get the electrician in and have a chat. If I turned up to find a pile of random materials from Ebay sat in a shed I would turn round and go home. I would posibly be happy with giving the customer a list of parts to get with the understanding there is absolutely no warranty on customer supplied parts.

Assuming that the electrician is going to be ripping you off for some reason before even starting the job is the right way to end up with only the cowboys who will fit any old crap left on your shortlist.

 

[Sharpend]

Perhaps a request of one of the members on here who may be local to you, might be a better starting point? There's often nothing better than a visit, coffee and a chat to discuss your plans/ideas to achieve the desired outcome.

At that point you can decide how you wish to proceed with your electrician.

Good luck

 

[Evans Electric]

I'd go with what the otheres have said ...get a few quotes , let the sparks supply the stuff. Far better that way .   You want something like a 30 amp supply . 

What you don't want is an electrician digging your trench ...........too expensive !!!    Do it yourself or get a builder's labour in for the weekend .

Lay a duct fotr the telecoms /data  stuff    and lay the mains cable in the ground but  seperate to the other stuff , as Dave says. 

 

[Murdoch]

I've got a few rules:

1. Customer supplies materials

2. I up my hourly rate

3. I charge by the hour for ALL the time wasted with the wrong parts supplied

4. Customer is on their own if anything goes wrong.

Simples

 

[apprentice87]

HI Gillingham,

Get a few electricians to give you quotes, and then come back and tell us what they recommend in the way of types and sizes of cables etc, and then we we tell you what we think..

Cable spec to shed depends on lots of things, one being the type of supply to your house and the preferences of the electrician as to the type of earthing system he wants to use in your shed.

What type of construction is the shed itself?? what other services will be connected to the shed??

john..

 

[M107]

Over the weekend I did a 50mtr submain to the same sized outbuilding/workshop (log cabin type thing) terminating into one of SBS Daves cu's + 10 sockets with 2x 6ft HF battens & 2x coach lamps (no data or phone)..........£1300 give or take a few quid, that include supply of materials & the associated warranties, what you need to decide is are you happy to use kit off ebay with no warranty but more so will you get somebody to fit the stuff?

And no i didn't dig the trench  I did however go under the floor void to get across the house to the meter location in the middle of the property.

be up to 40m away from house with main CU a further 5m away 

You need to do some cable calcs. How are you connecting your submain/circuit cable to the supply (1) via a switch fuse & splitting the tails or (2) as a circuit from the house cu.

have 2 light fittings (probably 2 x twin flourescent tubes unless anyone recommend something else?)

Fluorescent battens are fine but I'd go for High Frequency units.

have up to 8 double sockets (for convenience rather than use!)

Have as many as you like, the job at the week end I put two socket circuits in as radials.

In the middle of winter circa 21:00 I will have at most an electric heater on, a computer, another computer monitor, a TV or radio, both sets of lights, my mobile charging up and a kettle  ; &gt

Still need to do the calculations for cable sizing & believe me you will end up using more appliances than you expect.

What is the spec for a 2 or 3 circuit CU in the workshop?

The unit I put in was a 6 way unit (5 in use 1x spare way)with RCBO's for all circuits

What is the spec for the armoured cable running from the house?

Depends on how you are going to wire the installation & the cable calculations for cable sizing. Me I went for a TT at the outbuilding end so used 2 core swa & with the future expected load 16mm csa.

What is the spec for the cabling inside the workshop?

Up to you & how much you want to spend.....singles in conduit or twin & earth in trunking or twin & earth clipped direct or as I did use FP200 2.5mm for sockets & heater circuits & FP200 1.5mm for the lighting circuits.

Is there any minimum spec for the socket back boxes and face plates or can I just go for the cheapest?

Again up to you but experience says........buy cheap buy twice! I use BG Nexus white accessories & conduit back boxes to terminate nylon glands into.

 

[Gillingham]

Thanks to everyone responding - most appreciated as I was trying to understand what I don't know I don't know or as Runsfeld would have said "unknown unknowns".

We're on a tight budget so getting a list of supplies from electrician sounds good - we have a lead time of about 5 months so it's possible we can pick-up some heavy discounts beforehand.

We hadn't even considered getting ripped off so thanks for highlighting that as as potential problem to look out for.

 

[kerching]

See the FIRST line of my signature, please!

Just advising

 

[Murdoch]

Thanks to everyone responding - most appreciated as I was trying to understand what I don't know I don't know or as Runsfeld would have said "unknown unknowns".

We're on a tight budget so getting a list of supplies from electrician sounds good - we have a lead time of about 5 months so it's possible we can pick-up some heavy discounts beforehand.

We hadn't even considered getting ripped off so thanks for highlighting that as as potential problem to look out for.

Doubtful to say the least.

Start by getting 3 seperate quotes from sparks - and I for one will not give a list of parts to a customer. Sure you can buy specific lights but all the parts - rock on.

Out of interest how much do you think it would cost?