Commercial premises electrics questions

[MattH]

For a temp solution to my power requirements (which will all be at the far end of the unit away from the DU), would I be OK using a sub panel like this:
I could run a single suitably sized SWA cable down to it.



This would give:

1 X 32a 415v
1 X 16a 415v
2 X 16a 240v

All protected by an RCD and indvidual MCB's.

As I said this would be treated as a temporary quick fix to get me up and running with the minimal hassle. Later I would start running in all new high level trunking as suggested.

 

[MattH]

Is it Unistrut or lighting trunking? there's a big difference in use.

Just noticed that you made your text links to the products. What an incredibly helpful post!

 

[Robotstar5]

For a temp solution to my power requirements (which will all be at the far end of the unit away from the DU), would I be OK using a sub panel like this:
I could run a single suitably sized SWA cable down to it.

View attachment 82734

This would give:

1 X 32a 415v
1 X 16a 415v
2 X 16a 240v

All protected by an RCD and indvidual MCB's.

As I said this would be treated as a temporary quick fix to get me up and running with the minimal hassle. Later I would start running in all new high level trunking as suggested.

Do you want one of those distribution panels?, I've got one in the shed I've been meaning to sell for ages, will get a pic & details tomorrow if you're interested.

 

[MattH]

Yes mate, PM me the details when you get a moment please.

 

[Robotstar5]

Yes mate, PM me the details when you get a moment please.

Will do.

 

[Robotstar5]

Power distribution box, 32A & 16A 3 phase, 16A 230V, 13A socket & 2 x 110V socket (need external transformer)

Max load is 40A input

 

[Kent]

Is it rent or lease is it a repairing lease etc - what are your obligations and what are thiers?

 

[MattH]

It's actually a very simple license. Nothing is mentioned on interior fixings etc and as I said before the landlord's stance is that anything beyond the DU is nothing to do with him.
I'm not really bothered as I said, the electrics were never going to be at the level I need to run multiple cnc machines. I have no issue bringing it up to standard other than having the time to get it all done. Hence an interim solution to get us up and running ASAP.

 

[knighty]

for a factory I'd miss out all the trunking and conduit etc..

go with SWA fixed straight to the wall for all the 3 phase stuff

for single phase you can go with twin and earth clipped to the wall, or if you want to be a bit more fancy you can go with armour plated stuff fixed straight to the wall

it's cheaper and quicker to install like that, plus makes maintenance and future changes much easier

don't wire anything in direct, use a plug and socket for everything, single and 3 phase

use the same 3 phase sockets for everything, if 32amp is the biggest you need then put 5 pin 32amp plugs/sockets for everything, that way anything can be plugged in anywhere else if you need to move things around in a hurry
(use all 5 pin, no 4pin)


re-wired at work like that a few years back and it made everything much much simpler

for me, when it comes to work space, simple is king

 

[MattH]

for a factory I'd miss out all the trunking and conduit etc..

go with SWA fixed straight to the wall for all the 3 phase stuff

for single phase you can go with twin and earth clipped to the wall, or if you want to be a bit more fancy you can go with armour plated stuff fixed straight to the wall

it's cheaper and quicker to install like that, plus makes maintenance and future changes much easier

don't wire anything in direct, use a plug and socket for everything, single and 3 phase

use the same 3 phase sockets for everything, if 32amp is the biggest you need then put 5 pin 32amp plugs/sockets for everything, that way anything can be plugged in anywhere else if you need to move things around in a hurry
(use all 5 pin, no 4pin)


re-wired at work like that a few years back and it made everything much much simpler

for me, when it comes to work space, simple is king

Excuse me for saying but that seems wrong on a number of different points.

If I put 32A TP+N plugs on everything I could be plugging in something that has a 16A requirement but the supply could pump in 32A all day long (during a fault condition) without tripping a breaker.
Some things will have to be wired in and not via a plug as they will require a DOL starter and a C rated breaker whereas other things will not have this requirement.
T&E clipped directly to the wall does not sit well with me due to it not having a physical protection against damage (My garden shed is completely SWA with metal clad sockets etc), seems a bad idea in a workshop environment.

 

[dobbslc]

Swa is quick and simple in a builing like that also fairly damage proof...
Make sure you use either 5 core cable or 4 core with a run of separate earth with that temp supply unit. You can run an earth fly lead off the brass banjo if you want but it's not the best way. You wouldn't believe the amount of unearthed temp supplies I've seen because the cable gland was connected to a plastic box and not connected to anything.

 

[MattH]

Swa is quick and simple in a builing like that also fairly damage proof...
Make sure you use either 5 core cable or 4 core with a run of separate earth with that temp supply unit. You can run an earth fly lead off the brass banjo if you want but it's not the best way. You wouldn't believe the amount of unearthed temp supplies I've seen because the cable gland was connected to a plastic box and not connected to anything.

I was planning on using a Piranha nut to take an earth from the SWA armour.

 

[knighty]

Excuse me for saying but that seems wrong on a number of different points.
If I put 32A TP+N plugs on everything I could be plugging in something that has a 16A requirement but the supply could pump in 32A all day long (during a fault condition) without tripping a breaker.
Some things will have to be wired in and not via a plug as they will require a DOL starter and a C rated breaker whereas other things will not have this requirement.
T&E clipped directly to the wall does not sit well with me due to it not having a physical protection against damage (My garden shed is completely SWA with metal clad sockets etc), seems a bad idea in a workshop environment.

the breaker is just to protect the cable, socket on the end of it, the the plug that's plugged into it and the cable to the machine

every machine should have it's own breaker/fuse/whatever mounted in/on it

any starter / control box etc.. even if mounted to the wall is best wired to a plug and then plugged into a socket

most of my breakers in the main fuse box are 32amp D rated

there's a couple of bigger ones (wired to bigger sockets) and then the about a dozen single phase


dobbslc is right about using 5 core vs 4core, earth the armour as normal with a gland on the end (or a Piranha nut, I like glands) and then take the earth wire and wire that into the earth buss bar in the fuse box

doesn't make much difference at the fuse box end, but at the other end of the cable it makes things much easier when you have an actual earth wire to wire in (especially with a socket on the end, but even if they go into anything else)


all my stuff I wired up myself, left the socket open and then had a sparky wire in the fuse box end, screw the socket shut and then give me a ticket to say it's done right



plugs/sockets sound like a pain in the ****, but they're miles better in the long run. I changed to using them when I fully re-wired the factory about 8 years ago. looked around a lot of other factorise and talked to the electricians working in them and they all said the same thing, use a plug and socket every time. most of the time it makes no difference, but that one time you need to move a machine, get a new machine in, work on a machine etc. etc. etc. it makes everything infinitely easier.

most of my stuff is big motors, have about 10 x 30hp motors different in machines, so it's not small hobby stuff

plus, I'm guessing you'll be the same that if something breaks you'll want to fix it asap, or if something needs maintenance you'll want it done and out of the way so you can get back to work - being able to unplug a machine while you work on it makes everything miles easier, no having to check you've turned the right breaker off etc..


sorry to post such a wall of text, I don't mean to tell you what to do, I just really believe in what I'm saying

same way I guess you'd post about CNC machines etc..

 

[MattH]

The trouble with your approach is the fault condition disconnect times.

I can't imagine that the disconnect time on a 16A load plugged in to a 32A D curve breaker is going to be anywhere close to the regs.

I agree on using sockets whenever possible but C and D curve breakers should only be used for appropriate loads (yes large motors) and if you are using matching sockets for everything you can never ensure that the load is matched to a correct breaker.

My large motor loads (a couple of 10HP side channel blowers) will be hard wired via DOL starters to a dedicated matched (probably C curve) and sized breaker.
Everything else (CNC machines, Extractor pumps etc) will be on plugs and sockets (matched to their rated input current).

The hassle of un-wiring something should it go faulty verses the stress of killing a future employee seems rather minor.

 

[knighty]

the 32amp breakers are in the main distribution box, then each machine has it's own breaker in it's control box

the 32amp D rated ones only cover the cable into the machine and they go straight into the correct rated breaker for the machine


something I forgot to say is put the sockets up high, 6ft in the air keeps them out of harms way


for the 10hp blowers, when you say DOL starters I'm guessing just a contactor and not star delta (slow start)

either way, why not fix the control box to the wall, then have a wire coming out with a plug on the end ?

 

[WorkshopChris]

Once you start fitting D rated breakers the installation needs careful consideration especially with Sockets.
I personally would not want a D rated socket outlet without RCD protection.

 

[brightspark]

u can run a 30 amp 3 phase ring or radial sockets around your workshop and plug all your machines in providing u wire out of plugs in 4mm cable to the machines and they must have switchfuses fitted to the machines with appropriate down rated fuses fitted but for smaller gear that's portable say 16 amp or less u would need switchfuses wired in to the30 amp ring on wall and drop out to 16 amp sockets .as above b rated breaker unless a dedicated supply to a particular machine that would require it on start up

 

[dan.taylor.1]

Can't you get sockets with a breaker in them? Surely eine seen 32a single phase ones anyway.

 

[Robotstar5]

Can't you get sockets with a breaker in them? Surely eine seen 32a single phase ones anyway.

Ceenorm do them.

 

[knighty]

apart from a little 5kw fan heater, everything I have that runs 3 phase has it's own internal breaker anyway, must be over 20 different things, different makes etc..

problem you have fitting different sized sockets is when you go to plug something in and it's the wrong size socket - you end up needing twice as many sockets