Shed wiring

Merch

I am thinking of doing or getting a block shed done, but I would like power out there, lights and few sockets, maybe able to take the load of an arc welder (considering future possibilities.

I was thinking I need armoured cable, not sure what the overall diameter is or what sq cross section armoured cable is?. I'd plan to dig a small trench to put it in, I'd like the cable to look as unobtrusive as possible but even if I cut off a section of the concrete path beside the kitchen the wiring will still to have to come out so I can get it into the kitchen presumably above the dry course, can you get glands to seal these, or is it just a matter of drilling a hole and getting a sealant in there.Not sure how flexible armoured wiring is either.
Kitchen being opposite side of house to the consumer unit, I was thinking I could put a junction in when the armoured cable comes into the house, are there specific connectors for this?

Buford T Justice

Merch wrote: »

I am thinking of doing or getting a block shed done, but I would like power out there, lights and few sockets, maybe able to take the load of an arc welder (considering future possibilities.

I was thinking I need armoured cable, not sure what the overall diameter is or what sq cross section armoured cable is?. I'd plan to dig a small trench to put it in, I'd like the cable to look as unobtrusive as possible but even if I cut off a section of the concrete path beside the kitchen the wiring will still to have to come out so I can get it into the kitchen presumably above the dry course, can you get glands to seal these, or is it just a matter of drilling a hole and getting a sealant in there.Not sure how flexible armoured wiring is either.
Kitchen being opposite side of house to the consumer unit, I was thinking I could put a junction in when the armoured cable comes into the house, are there specific connectors for this?

If i was you, I'd get a spark in to do it, if you don't know these bits.

Merch

I've a bit of experience doing jobs, but I just haven't tackled one like this.
that's why I'm asking and also because I simply don't really have the money to get someone in.
Anyway, even if I did get someone in to connect it, it could be some time before that is needed as I'd have to build the shed around it:) and I'd like the cable underground and in both the shed and house(kitchen) before connecting it up. So looking for ideas about how to get the cable into the house and what kinda connection to make with say a 16sq cable to the consumer unit.
The reason I ask what csa armoured cable is (well I dont know what csa it is), I'd like to be able to calculate the voltage drop, I don't think its practical,possible or cost efficient to run the armoured cable to the other side of the house where the consumer unit is so I will need some kind of junction just inside the kitchen where the cable will enter the house. I'd planned to use as large csa as possible from the armoured cable to the consumer unit or simply one equivalent to the armoured cables csa.

I dont think there are going to be any issues with earth line impedance as I am connecting something off the shelf wiring/connectors into an existing installations earthing, but I would plan to have it protected by an rcd anyway. I aim for diy power tool usage but I'd like to have the wiring to have the capacity to be take the load of an arc welder, I can change the CB types later if need be.

I appreciate your advice but, its not exactly the direction I am looking.

Randyleprechaun

Hi,is is a bungalow or a two storey house?

First advice is to get someone who knows exactly what they are doing but here's what I would do.

1. Run a 3X10 SWA (if the distance isn't massive)from the shed to the footpath, cut the footpath, if it's a bungalow run the cable iup the outside wall and saddle it on or use cleats. Run in through the soffit, across the attic and down to your consumer unit. If it's atwo storey then run the cable into your kitchen to where you propose to put the junction box.
2. Use proper SWA glands on the SWA cable making sure that you earth the steel wire armour strands properly.
3. Use equivalent size alternative cable to connect to the SWA in the JB and run to consumer unit. Really you should run the SWA al the way to the consumer unit with no joint as it would be a better safer job.
4. Put a new switch fuse unit in your consumer unit with a 50A fuse in it. Coneect your 3 core cable up, making sure that it is not on the house RCD.
5. Put another switch fuse unit in the distribution board for the shed and put a 40A fuse in there.
6. Use 10A MCB's for your shed lighting.
7. Use 20A MCB's on an RCD for your sockets.
8. Use a 32A C or even D type MCB feeding a 32A blue socket for the welder. It should be good enough.

You should calculate that the 3X10 will not give excessive volt drop. 3X10 will carry the load no problem.

Make sure you test fault loop impedance and RCD trip times when done.


Job sorted!!!!

Merch

Randyleprechaun wrote: »

Hi,is is a bungalow or a two storey house?

First advice is to get someone who knows exactly what they are doing but here's what I would do.

1. Run a 3X10 SWA (if the distance isn't massive)from the shed to the footpath, cut the footpath, if it's a bungalow run the cable iup the outside wall and saddle it on or use cleats. Run in through the soffit, across the attic and down to your consumer unit. If it's atwo storey then run the cable into your kitchen to where you propose to put the junction box.
2. Use proper SWA glands on the SWA cable making sure that you earth the steel wire armour strands properly.
3. Use equivalent size alternative cable to connect to the SWA in the JB and run to consumer unit. Really you should run the SWA al the way to the consumer unit with no joint as it would be a better safer job.
4. Put a new switch fuse unit in your consumer unit with a 50A fuse in it. Coneect your 3 core cable up, making sure that it is not on the house RCD.
5. Put another switch fuse unit in the distribution board for the shed and put a 40A fuse in there.
6. Use 10A MCB's for your shed lighting.
7. Use 20A MCB's on an RCD for your sockets.
8. Use a 32A C or even D type MCB feeding a 32A blue socket for the welder. It should be good enough.

You should calculate that the 3X10 will not give excessive volt drop. 3X10 will carry the load no problem.

Make sure you test fault loop impedance and RCD trip times when done.


Job sorted!!!!

Cheers, its a two storey house,the shed position would be about 5 metres away from the house but that end of the house is probably 15 metres (including 2m at each end) from the consumer unit. I'd prefer to run it without junctions, but I don't think I will be able get armoured cable through the places it will need to go.

That all sounds good, I'm not sure how to measure the impedance or the trip time,
Is it a matter of connecting the earth to another wire of the same size, measure the resistance for the loop and then half that figure?
Once I have that figure I can determine how long the time will be using the fuse characteristics, but presumed it is standard for the CB's and standard or 30mS for RCD.
I plan to work it out to just to make sure, just never measured an impedance/ohms.

Randyleprechaun

Over that distance, I can guarantee you that 3X10mm will be fine. Don't bother even calculating it.

To measure the fault loop impedance when the job is done and the trip times you will need a special meter and more importantly, someone who knows how to use it. it's not rocket science anyway!!!!

Merch

I was going to calculate the voltage drop over the distance to determine the csa size, If you say 3x10 is fine. I mainly wanted to calculate the fault loop impedance, but if it requires special meter, hmm
I didn't think it would be rocket science, I'd be as much interested to do it for the experience, its all in the prep stage anyway.

Thanks for the advice.

M cebee

you can calculate the VD for the 'sub-main' and 'final circuit' using the rating of the 2 protective devices and cable sizes/length

the loop impedance at the shed sockets will be the Ze(external loop impedance) at the house + R1+R2 for the submain and final-circuit(phase and earth with no parallel fault paths included)

that can be estimated too before you start.

the disconnection times for 'D' type mcbs will prob be hard to meet

don't like the 50amp and 40amp in series -can't see the point -i would fit protective device on sub-main and 'isolating switch' in shed

Bruthal

wiring a shed is turning into rocket science now is it

Merch

Just want to make sure I've got adequate earthing/protection

jeepers101

Merch if you're in Dublin give me a shout when you're done and i'll measure the impedance for you. Takes two minutes.

Merch

cheers for that, just have to build the shed first though, so could be a little while, need to find out how much for someone to lay blocks, might try do the rest myself.

noddyk

Randyleprechaun wrote: »

Hi,is is a bungalow or a two storey house?

First advice is to get someone who knows exactly what they are doing but here's what I would do.

1. Run a 3X10 SWA (if the distance isn't massive)from the shed to the footpath, cut the footpath, if it's a bungalow run the cable iup the outside wall and saddle it on or use cleats. Run in through the soffit, across the attic and down to your consumer unit. If it's atwo storey then run the cable into your kitchen to where you propose to put the junction box.
2. Use proper SWA glands on the SWA cable making sure that you earth the steel wire armour strands properly.
3. Use equivalent size alternative cable to connect to the SWA in the JB and run to consumer unit. Really you should run the SWA al the way to the consumer unit with no joint as it would be a better safer job.
4. Put a new switch fuse unit in your consumer unit with a 50A fuse in it. Coneect your 3 core cable up, making sure that it is not on the house RCD.
5. Put another switch fuse unit in the distribution board for the shed and put a 40A fuse in there.
6. Use 10A MCB's for your shed lighting.
7. Use 20A MCB's on an RCD for your sockets.
8. Use a 32A C or even D type MCB feeding a 32A blue socket for the welder. It should be good enough.

You should calculate that the 3X10 will not give excessive volt drop. 3X10 will carry the load no problem.

Make sure you test fault loop impedance and RCD trip times when done.


Job sorted!!!!

Hi

Sorry to but in , but I am doing similar work myself. Does the cable from the house to the shed need to be ducted ? If so what size duct ???

owen85

noddyk wrote: »

Hi

Sorry to but in , but I am doing similar work myself. Does the cable from the house to the shed need to be ducted ? If so what size duct ???

dont worry youre not butting in, youre 5 years too late to butt in.



youd probably want to start a new thread

thread was from 2010