Workshop build

[Jaco]

Looks great! want to see how you lay out in the shape.
pity no windows, i believe in having some natural light.

 

[Anonymous]

Jaco having no windows were i live is a good choice as most of my kit would be gone by morning (they would bash through the window or walls, they would have no luck at the doors :lol: ) SD i plan on putting a powertool store at the very end of the pointy bit then a grinding and sharpening station next to it .I have not been able to get out there this weekend as my backs been twinging from painting the floor and a full weeks work next week. On the up side i should make enough money to order a 3hp DE and timber for making the benches . Will hopefully post some more pickys next weekend .Thanks for showing an interest and any ideas for thing at this stage would be great .

 

[Woodythepecker]

AP,

What a fantastic use of what many of us would see as dead space. Go to the top of the class and take one hell of a pat on the back.

I notice that you have installed dpm. Well i have just got my first workshop and i am going to either put plaster board or chipboard on the walls. These walls are made of brick and i was thinking about putting dpm under the sheeting, would you agree with this?

I am also going to upgrade the electrics. Is there anything you suggest installing?

Good luck with your new workshop

Woody

 

[Anonymous]

Thanks for your kind words woody .DPM or building paper is to me a must if you are dealing with a single skin wall ,the floor DPM overlaps the wall DPM in my build so no chance of water ingress also important to put in weep holes so if you do get water in it has a path out. I chose T & G moisture resistant chipboard for the walls so i am not restricted for putting thing up (i dont have to find studs for a decent fixing). On the electrical side of things i installed a 10mm SWA to the workshop (2core + earth) also a seperate earth on a 2m stake , i have also installed an RCD and a consumer unit with MCB protection on all circuits with a few spares for expansion . I have 2 X lighting circuits, 1 X 13amp socket ring main ,3 X 16amp radials for machines. Maybe a bit OTT but if your gonna start from scratch its well worth the effort.

P.S The 10mm steel wire armoured cable is above ground as the AMP rating is higher than if you bury it .If you are not confident with electrics then i would strongly advise getting PRO HELP .

 

[Woodythepecker]

Phily the advice is much appreciated. I will certainly be using dpm now.
What is the separate "earth on a stake" for?

I am pretty thick when it comes to electrics so i intend to get a pro's advice as to what i can and cannot use, and i will then run all the wiring and sockets etc myself and then get him back to check it all over and actually connect it to the mains. Should save a few quid.

Thanks again for your advice

Woody

 

[Anonymous]

the earth stake is just an additional earh for the workshop a bit belts and braces .Basically its a copper rod driven into the ground with 100mm left sticking out for you to attach an earth wire to then connect to your consumer unit .Realy you dont need 2 earths but thats just me going OTT again :lol:

 

[Anonymous]

AP

the earth stake is just an additional earh for the workshop a bit belts and braces.

I've never tackled external wiring but I've just got a niggling idea in the back of mind from somewhere that if the house TN (-C, -S or -C-S) earthing arrangements and the workshop TT arrangements are not isolated that a situation can arise where the house earth is at a higher potential than the local earth. I'm no expert and I can't really think how this would arise or why it would be a problem unless it's something to do with the RCD requirements for TT installations. You may be more knowledgeable on this than me and perhaps I've got it mixed up but I just thought I'd mention it FWIW.

Regards

Roy

 

[Jaco]

[having no windows were i live is a good choice as most of my kit would be gone by morning ]

AP, sounds like you live in South Africa!
WE burglar bar and alarm everything in site!

 

[Anonymous]

Roy the house earth stake is only 18" from the consumer unit the house also has RCD protection (both stakes are within 2m of their consumer units) there is no problem having multiple earths providing they are linked take cross bonding on copper pipes in your house (simple multiple earths cold main and gas pipes are/should be earthed. The only time you got a problem is when you have no earth the good thing about earthing is you cant realy go wrong if you keep it short (route wise) and correct size earth cable ,electricity is very lazy it always looks for the shortest route to earth .RCD's are a must .

 

[blurk99]

Hi AP

can i just ask if you made the final connection to the consumer unit in the house? What i want to know is - is it easy to do? i've seen it described in books but i'm aware that there's about 100-120 Amps going through the company fuse if it all goes pear shaped...

cheers

Jim

(lovely looking workspace BTW)

 

[Adam]

Hi AP

can i just ask if you made the final connection to the consumer unit in the house? What i want to know is - is it easy to do? i've seen it described in books but i'm aware that there's about 100-120 Amps going through the company fuse if it all goes pear shaped...

cheers Jim (lovely looking workspace BTW)

I did the wiring in my workshop, and although you can work live on my consumer unit, not surprisingly I decided to switch it off! My main house fuse (the electricity company one) didn't have any security seal on it, so I just pulled that out, and did the final wiring. From what I've seen of electricians none of them bother ringing the electricity company to tell them they are going to break the seal and disconnect it, they just get on with it and don't worry. How nervous you should be depends on how confident you are in your wiring I guess! You could always start by using a very low amp breaker in the main consumer unit, to the shed, or say an amp or two so it burns out super quickly if you have made a mistake. I just hit the "on" switch myself... you're making me think I should have spent more time testing it now!

Adam

 

[Anonymous]

Guys

If I could just WARN you here. It only takes 30mA to kill if it flows across your chest. 240V is a lethal voltage.


Don't work live.

 

[Adam]

Doh, I wrote a post and edited in and it's AWOL now...

"as Tony said", was the general jist of it.

Adam

 

[Anonymous]

AP

Ah, so you have a TT system on the house as well.

My niggly worry arises if the house is TN. I mean you have an equipotential zone in the house from the supplementary bonding. If your house earth then goes out to the workshop and rather than that being completely isolated on its own TT system it also connects with the house TN system how does this affect the equipotential zone in the house and you in your workshop? Or does it?

Like I say I can't envisage ever doing external wiring so I've never really looked into and so maybe this is all a red herring. I'm just concerned that there may be an issue for other people with TN supplies and perhaps you can put my mind at rest that no issue arises.

Regards

Roy

 

[Anonymous]

With a TT system supplied to the house (no earth connection from electricity supplier - usually rural installations only), the installation requires a 30mA RCD and the neutral and earth cables must be kept separate (normally the neutral is earthed at the generating station as it is at a 3-phase star point which = 0V).

For a garage installation with a TN-S electricity supply to the house (most common in England where the leccy board provides an earth terminal), the earth is connected to the star point on the generator's star point (neutral) where it is connected to a copy earth spike.

I would say that it is a bad idea to use an earth spike with a garage/shed installation that has a TN-S supply as the earth potential at the garage will be different to that at the house due to voltage drops and induced voltages in the various conductors (including the earth itself). I would suspect that this arrangement might cause nuisance tripping of RCDs as they operate on imbalances between conductors.

AP, if it was me, I would not sink a second earth spike but run the earth from the house through the armour on the cable as well as the protective conductor. Multiple earthing points are bad practice and result in earth loop potentials developing which may cause false trips on RCDs

The max earth loop impedance you should have is 220 ohms (16th edition regs which is latest I have (17th 2004 edition is expensive!!))

10mm SWA (steel wired armour) should be OK buried with a 32A RCD (OK up to about 46A) consumer unit plus it would be less likely to be damaged by heavy (sharp) objects hitting it!!

 

[Anonymous]

My electrical knowledge as a heating engineer, i have to know a lot about complicated circuits so house wiring seems easy to me i may not know everything there is to know about electrics and i am always willing to learn .In my trade i have to work live on almost everything to trace faults (taken a few 30amp belts ) but i would not advise anyone here to do what i do . Back to the subject of earthing, with RCD protection if a short occurs its almost instantly switched off by the RCD (live and Neutral)if the RCD should fail and i had a live running through the earth fulltime (exageration) if it did backfeed the workshop the worst that can happen is it goes down the earth stake out there and trips the RCD.(but as stated earlier it will take the path of least resistance ie: earth stake in the house , water pipe or even gas line as these are all earthed and are all made from conductive material, all earths in their own right). If working (disconnecting) earths you must make a temporary bond so if there is currant there it will still earth .You must check things out with a multimeter rather than a neon screwdriver as neon screwdrivers are no use other than doing up screws only this guy (homer) would use one for testing electrics. The laws of physics win everytime :lol: . I would be more worried if i only had a live and neutral in the sway going down there because if the cable was ever severed the only earth is you .I would be more concerned about reverse polarity in wiring (making sure the live is actually in the live part of a switch not the neutral) because when you throw a single pole switch with reverse polarity you turn off the neutral so everything beyond that point still has 240v running through the live wire (brown/red) and more importantly you also get 240v on the neural (blue/black). Thats why neutral faults are so dangerous and double pole switches are a good idea. With wiring as with all things double check all connections and if in doubt call in a PRO he will tell you what type of earthing system you have and if your existing house wiring is up to the job .I have had the electrics checked by the guy from the electricity board that came to fit a new seal to the main fuse he said everything was a bit OTT but was as safe houses (only cost me a cuppa 8) )

 

[Anonymous]

Tony

I would say that it is a bad idea to use an earth spike with a garage/shed installation that has a TN-S supply

Not sure I quite understand that. It seems to me if you are going to use an exported earth then you will have to create an equipotential zone that includes both the house and external shed or workshop which would be pretty difficult. Any fault to earth is likely to find its path to ground somewhere in the shed or through something in the shed (perhaps you)due to the differing potential between the house and the general mass of earth which parts of the shed may well adopt. I think it is better to sink an earth rod and have a TT system isolated from the house and thus create your own little Faraday cage out there.

AP

Still not sure about connecting the house and workshop earths if the house is one of the TN systems and the workshop is TT through its spike. I've been trying to think through various scenarios in both the house and workshop or failures in continuity at either end and how one would affect the other with regards to creating a difference in potential that could flow through you or someone in the house but I just get myself confused. I'm still not convinced it is a good idea but I have an open mind on it.

Roy

 

[Anonymous]

Thanks all for your input but everything has been tested and cleared and no problems .I have only been using fairly small power tools in the construction of benches so far 2000w router 1100w drill and have had no problems and no trips on the W/S RCCD or house RCCD .Any way lets get on with the progress so far at the weekend i am hoping to move the saw in to get these benches cracked out and tool store up and running as the tools in the house are starting to bug her in doors as every room now has a tool or several in it. I would also like to take stock as so far i have found 3 complete drill bit sets and at least 4 dewalt screwdriver bit sets 5 makita 9.6v batts things just keep turning up guess i am a sucker for a bargain when i see one

 

[Anonymous]

Roy

What I was saying is that by adding a second earth spike near the garage, you are setting two earth potentials (one in the house and a second in the garage) which will result in earth loop potentials which may well trip an RCD. It is bad practice to earth at more than one point.
AP does not have TT in house and TN in the garage as a TN-s system requires an earth from the Electricity supplier's star-tapped transformer. AP has a TT that is spured off to the workshop.


AP
I am not a house basher leccy either although I did an electrical ONC before my degree and about 6 years electrical/electronic fault finding (often live too ).
I am confused by the 30A shock? One cannot guage the shock current (dependant on body resistance and resistance between contact with conductor and contact with ground), only the voltage.
Last shock I got working live was 415V - I landed 6 feet away :roll:

Glad to hear the board singed off the installation ok. My comment was really that the RCD may nuisance trip due to earth loop potentials, not to say that this is unsafe, just a pain in the proverbial if it happens.

 

[Anonymous]

shock from a 30amp cooker supply(sorry did not make that clear) that some clever person pushed back into a stud wall and filled over , after checking both sides of the wall for lecky i assumed it was clear and so took out my trust sandvic and started to cut out a doorway after a loud bang sparks and flying off a pair of step i was ok but i lost 6 teeth off the saw . Also took a large belt in the chest from an industrial ignition transformer high volts low amps but it looked like 2 ciggy burns on my chest FYI i had isolated and taped the SFS but some bright spark removed the tape and switched on as i was working , no one there owned up to it :evil: