Tiny workshop - extension lead?

[Jack Pattenden]

Good afternoon all,

I'm in the process of planning out a tiny workshop (150cm x 150cm x 230cm) in what is currently a storage room on my balcony. Current issue is no power supply in there, and it's a rental property so I'm not keen on getting any installed.

Trying to avoid voltage drop as much as possible, my rough idea is an extension cable which goes:

13A heavy duty 3-pin -> short length of 2.5mm cable -> Commando socket -> 4mm cable -> Commando socket -> 4x or 5x 13A 3-pin distributor in the workshop

Will need to be ~5m total, max 10m, plugged into one of the 13A outlets inside. Will be replacing the MCB for this circuit with a C-type.

16A inverter MIG (will only be running it as high as 13A supply safely allows) and 13A 3hp air compressor will be the highest demand equipment in there - do you think they will tolerate running off this extension? Won't be running both at the same time.

Thanks for your help!

 

[hotponyshoes]

Have you got a spare way in the fuse box?
I' fit a 16a breaker and run 4mm from it.
Remove it and blank the hole when you leave

 

[Guineafowl]

Umm, you’ll be welding in the house, in a rental?

 

[Misterg]

Trying to avoid voltage drop as much as possible, my rough idea is an extension cable which goes:

13A heavy duty 3-pin -> short length of 2.5mm cable -> Commando socket -> 4mm cable -> Commando socket -> 4x or 5x 13A 3-pin distributor in the workshop

Will need to be ~5m total, max 10m, plugged into one of the 13A outlets inside. Will be replacing the MCB for this circuit with a C-type.

Have you worked out the voltage drop you're trying to avoid?

5m of 2.5mm^2 cable drops about 1.2V at 13A (0.5%). Don't over-complicate it.

You lay yourself open if you change the MCB to a type C - Someone needs to verify that the Zs is low enough to give you the required tripping time.

 

[octo0072000]

Don't want to pee on your ideas but
Doubt any insurance co will cover that let alone the rental co
i would think if the landlord see's that it might invalidate your tenancy

 

[Jack Pattenden]

Have you got a spare way in the fuse box?
I' fit a 16a breaker and run 4mm from it.
Remove it and blank the hole when you leave

As far as I can remember, no more space on the fuse box. I'll have to double check though as there might be a couple blanked?

 

[Jack Pattenden]

Umm, you’ll be welding in the house, in a rental?

Out on the balcony, brick room with plenty of ventilation and very convenient fire escape stairs down to the garden.

 

[Jack Pattenden]

Don't want to pee on your ideas but
Doubt any insurance co will cover that let alone the rental co
i would think if the landlord see's that it might invalidate your tenancy

I'm with a housing association, they don't give a monkeys, you never hear from them unless your rent account ever goes into arrears. I've asked their permission for all kinds of stuff over the years and been ignored each time, until one of them actually told me "don't bother asking, just do it". Shrug!

 

[Jack Pattenden]

Have you worked out the voltage drop you're trying to avoid?

5m of 2.5mm^2 cable drops about 1.2V at 13A (0.5%). Don't over-complicate it.

You lay yourself open if you change the MCB to a type C - Someone needs to verify that the Zs is low enough to give you the required tripping time.

Stick with the B then? I didn't want to deal with nuisance trips with startup current, but it is the safer choice.

I didn't have an exact number I was avoiding, just wanted to make sure I wasn't bottlenecking the supply at all, since I'm already using extension which isn't ideal.

 

[Guineafowl]

Out on the balcony, brick room with plenty of ventilation and very convenient fire escape stairs down to the garden.

Ah, couldn’t quite picture what you meant.

I made myself a custom 5m extension lead with 2.5mm2 flex. It only just fitted into the 13A plug and socket (might have been some dremelling to fit the insulation into the clamps) but it works well. Probably your best bet. If not, 1.5mm2 should be fine.

You might not need to swap to a type C breaker - see how it goes. As above, the circuit should be loop tested before making the change.

 

[cheb]

Are the breakers all the same make? Can you replace one with a used one that blends in?

 

[MetalMonkey]

Good afternoon all,

I'm in the process of planning out a tiny workshop (150cm x 150cm x 230cm) in what is currently a storage room on my balcony. Current issue is no power supply in there, and it's a rental property so I'm not keen on getting any installed.

Trying to avoid voltage drop as much as possible, my rough idea is an extension cable which goes:

13A heavy duty 3-pin -> short length of 2.5mm cable -> Commando socket -> 4mm cable -> Commando socket -> 4x or 5x 13A 3-pin distributor in the workshop

Will need to be ~5m total, max 10m, plugged into one of the 13A outlets inside. Will be replacing the MCB for this circuit with a C-type.

16A inverter MIG (will only be running it as high as 13A supply safely allows) and 13A 3hp air compressor will be the highest demand equipment in there - do you think they will tolerate running off this extension? Won't be running both at the same time.

Thanks for your help!

Replacing the MCB to a different curve would need the Zs checking to ensure tripping times are met, as said.
Regardless you are still hanging all that off one 13A socket, which are not designed for prolonged high loads. Especially the modern stuff with contacts from tin foil.

I'd suggest the biggest issue will be the compressor. My experience with 3hp compressors is they don't like to run on a 13A plugtops, despite what they advertise.
They can do, sometimes, and sometimes they pop fuses.

Do you have any unused shower or cooker circuits?

 

[Agroshield]

5m of 2.5mm^2 cable drops about 1.2V at 13A (0.5%).

With plumbing stuff, every 90 bend counts as 1m of straight pipe for flow restriction pruposes.

Is there any similar rule of thumb for electric where every plug/socket connection degrades the efficiency?

Would a 5m long cable on each item, plugged directly into the house socket be an option? You can only use one item at a time and it is not too far to go back to unplug one and plug in the next.

 

[Guineafowl]

With plumbing stuff, every 90 bend counts as 1m of straight pipe for flow restriction pruposes.

Is there any similar rule of thumb for electric where every plug/socket connection degrades the efficiency?

Would a 5m long cable on each item, plugged directly into the house socket be an option? You can only use one item at a time and it is not too far to go back to unplug one and plug in the next.

No rule of thumb that I know of, but yes, you’d class it as extra contact resistance, which might be measured live at the final socket as Zs, supply loop impedance. Sometimes, ‘exercising’ the switch or plugging/unplugging several times can improve things by cleaning contacts. One reason not to daisy-chain extension leads is, it might increase your Zs beyond that needed to pop the fuse reliably.

Good idea, one extension per machine. They’re not expensive.

 

[Jack Pattenden]

Are the breakers all the same make? Can you replace one with a used one that blends in?

Another thing to double check when I'm back home tonight...

 

[MoreWellie]

Ignoring the practicalities of welding inside something not much larger than the average outside toilet

If I needed to use an extension lead I would use a single lead from a 13a plug to a 13a socket made out of 2.5mm flex and as short as I could get away with

Be prepared to buy some 13a fuses as the compressor will likely blow them particularly on hot restarts

 

[Jack Pattenden]

Replacing the MCB to a different curve would need the Zs checking to ensure tripping times are met, as said.
Regardless you are still hanging all that off one 13A socket, which are not designed for prolonged high loads. Especially the modern stuff with contacts from tin foil.

I'd suggest the biggest issue will be the compressor. My experience with 3hp compressors is they don't like to run on a 13A plugtops, despite what they advertise.
They can do, sometimes, and sometimes they pop fuses.

Do you have any unused shower or cooker circuits?

No, unfortunately no shower or cooker circuits free.

I may well look into how easy (or difficult) putting a 16A breaker on the fusebox will be. Might be an option if it can be DIY'd.

 

[Jack Pattenden]

With plumbing stuff, every 90 bend counts as 1m of straight pipe for flow restriction pruposes.

Is there any similar rule of thumb for electric where every plug/socket connection degrades the efficiency?

Would a 5m long cable on each item, plugged directly into the house socket be an option? You can only use one item at a time and it is not too far to go back to unplug one and plug in the next.

Just putting longer cables on the machines is a pretty good shout. I thought it might get a bit annoying to exit, let myself back inside the flat, swap the plugs, head back out to the room, but realistically I won't be doing that often. Probably be using one machine one day and one machine the other.

 

[Jack Pattenden]

Ignoring the practicalities of welding inside something not much larger than the average outside toilet

If I needed to use an extension lead I would use a single lead from a 13a plug to a 13a socket made out of 2.5mm flex and as short as I could get away with

Be prepared to buy some 13a fuses as the compressor will likely blow them particularly on hot restarts

It seems 4mm Vs 2.5mm is negligible, so if I can save a bit and just have a 13A 2.5mm lead, I'm happy.

You'd be surprised! I can get two shelving units and a workbench in there and still have some pretty comfortable standing room in the middle of it all. Definitely not swinging a cat though.

 

[gaz1]

if you fit a diy fuse and 16amp setup you will need to have it checked if in the event anything happens it wont go well for you as your renting

just get the 16amp and have it wired to a blue connector and have that tested nothing else is needed anything else after that is your issue and not anything to do with the renting place

if you want to wire it all in just get the fuse and wire to a consumer unit in the shed and split what you need in there when you leave take it all with you

the issue stands if anything happens you will be at fault so remember that as that would mean they wouldnt have to rehouse you as its your fault if anything did happen

becareful within rented propertys