Looks like I'm going ahead with 3 phase into the new workshop. This is
mainly to power fixed machinery, but some socket (welders, compressors
etc.) would be useful too.

What's a good book to start reading? My current 16th ed on-site
covers almost nothing useful here. Is there an industrial equivalent?

There's also the issue of the workshop being near to, but separate
from, the house itself. Some "workshop" "sheds" are inbetween them
(connected to the house, if anything). One of them is a place I'd
particularly like to have robust sockets (physically and electrically)
to drive welders. What are the issues about supplying this either from
the house or the workshop incomers?

Andy Dingley coughed up some electrons that declared:


There's also the issue of the workshop being near to, but separate
from, the house itself. Some "workshop" "sheds" are inbetween them
(connected to the house, if anything). One of them is a place I'd
particularly like to have robust sockets (physically and electrically)
to drive welders. What are the issues about supplying this either from
the house or the workshop incomers?

Commando sockets (16A or 32A) any good?

You'd normally (in my computer room experience of those) run them as
radials, often with only one socket per circuit if it *is* going to be used
all the time.

Do you want 3 phase or single on those (either is available)?

The only issue I've come across with outbuildings is whether to export the
house earth to them or to have a local TT rod + suitable RCD protection.

There was an IEE Wiring Matters article on this IIRC - want me to dig out a
URL?

Adam (to cite just one) will know a lot more about this, so I'm not
volunteering much 'cos I've not touched a lot of 3 phase.

Cheers

Tim

"Andy Dingley" wrote in message
...
Looks like I'm going ahead with 3 phase into the new workshop. This is
mainly to power fixed machinery, but some socket (welders, compressors
etc.) would be useful too.

What's a good book to start reading? My current 16th ed on-site
covers almost nothing useful here. Is there an industrial equivalent?

Anything that deals with the full regs. Your local library ought to have
something.

Three phase is run as radial circuits. If for an industrial installation and
subject to HSE inspection, each machine must be provided with local
isolation and an emergency stop.

Good practice, although not mandated, is for single phase socket outlets or
lamp sockets on different phases to be at least six feet apart. Personally,
I also colour code socket outlets with a bit of tape around the conduit
leading into the box, so you know when you might be bringing two phases into
close proximity.

Any place where single phase might be expected, but where two or more phases
are present, for example inside a multiple light switch, must be marked
externally with a warning of the higher voltage.

There's also the issue of the workshop being near to, but separate
from, the house itself. Some "workshop" "sheds" are inbetween them
(connected to the house, if anything). One of them is a place I'd
particularly like to have robust sockets (physically and electrically)
to drive welders. What are the issues about supplying this either from
the house or the workshop incomers?

Make sure it is from one or the other, but not both, to avoid the
possibility of having some circuits live when you think the supply has been
isolated. As already mentioned, you also need to decide whether you are
going to export the earth or have a local earth.

Colin Bignell

In article ,
nightjar cpb@insert my surname here.me.uk wrote:
Good practice, although not mandated, is for single phase socket outlets
or lamp sockets on different phases to be at least six feet apart.
Personally, I also colour code socket outlets with a bit of tape around
the conduit leading into the box, so you know when you might be
bringing two phases into close proximity.

Could you not keep all the GP sockets and lighting on one phase - given in
most of this sort of workshop the majority of the load will be hard wired?

--
*Why is the word abbreviation so long?

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
nightjar cpb@insert my surname here.me.uk wrote:
Good practice, although not mandated, is for single phase socket outlets
or lamp sockets on different phases to be at least six feet apart.
Personally, I also colour code socket outlets with a bit of tape around
the conduit leading into the box, so you know when you might be
bringing two phases into close proximity.

Could you not keep all the GP sockets and lighting on one phase - given in
most of this sort of workshop the majority of the load will be hard wired?

I'm used to factories where the lighting load needs to be balanced across
phases, let alone the single phase socket outlets. However, for a small
workshop, where there is not likely to be a need to balance loads, that
would be a perfectly acceptable answer.

Colin Bignell

On Mon, 20 Oct 2008 18:56:00 +0100 someone who may be Tim S
wrote this:-

Commando sockets (16A or 32A) any good?

You'd normally (in my computer room experience of those) run them as
radials, often with only one socket per circuit if it *is* going to be used
all the time.

The 32A size and above should always be wired on individual
circuits.

16A sockets may be wired more than one to a circuit, if diversity
allows for it to be done. That is useful for sockets which are
seldom likely to be used simultaneously.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

In article ,
nightjar cpb@insert my surname here.me.uk wrote:
Could you not keep all the GP sockets and lighting on one phase -
given in most of this sort of workshop the majority of the load will
be hard wired?

I'm used to factories where the lighting load needs to be balanced
across phases, let alone the single phase socket outlets.

Yes - I can see that. But in a large building it would be fairly easy to
group stuff to minimise the risk of having adjacent outlets on different
phases?

However, for a small workshop, where there is not likely to be a need to
balance loads, that would be a perfectly acceptable answer.

I was thinking of TV studios where they tend to keep all GP outlets on one
phase but where the large load, ie lighting, is on three. The thinking
being that you're more likely to get some form of fault on a portable
appliance fed via an extension lead than something which is near
permanently plugged in.

--
*Being healthy is merely the slowest possible rate at which one can die.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
David Hansen writes:
On Mon, 20 Oct 2008 18:56:00 +0100 someone who may be Tim S
wrote this:-

Commando sockets (16A or 32A) any good?

You'd normally (in my computer room experience of those) run them as
radials, often with only one socket per circuit if it *is* going to be used
all the time.

The 32A size and above should always be wired on individual
circuits.

16A sockets may be wired more than one to a circuit, if diversity
allows for it to be done. That is useful for sockets which are
seldom likely to be used simultaneously.

Wiring regs used to allow 16A sockets on circuits fused at up
to 20A. I don't have any wiring regs handy at the moment to
check the current status.

None of these are shuttered, so they can't be used around the
home. (If you still do, make sure they're positioned well out
the reach of children.)

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Andrew Gabriel wrote:
Wiring regs used to allow 16A sockets on circuits fused at up
to 20A. I don't have any wiring regs handy at the moment to
check the current status.

None of these are shuttered, so they can't be used around the
home. (If you still do, make sure they're positioned well out
the reach of children.)

Many have a heavily sprung loaded cover for when there's no plug inserted
- and that would defeat most small children. They've taken skin off me
before now. ;-)

--
*If you tell the truth, you don't have to remember anything.*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) coughed up some electrons that declared:

In article ,
Andrew Gabriel wrote:
Wiring regs used to allow 16A sockets on circuits fused at up
to 20A. I don't have any wiring regs handy at the moment to
check the current status.

None of these are shuttered, so they can't be used around the
home. (If you still do, make sure they're positioned well out
the reach of children.)

Many have a heavily sprung loaded cover for when there's no plug inserted
- and that would defeat most small children. They've taken skin off me
before now. ;-)


And you can get ones with an interlocked isolator - I rather fancy a couple
of these on the side of my house.

On 21 Oct, 00:52, "nightjar" cpb@insert my surname here.me.uk
wrote:
"Dave Plowman (News)" wrote in ...

Could you not keep all the GP sockets and lighting on one phase - given in
most of this sort of workshop the majority of the load will be hard wired?

I'm used to factories where the lighting load needs to be balanced across
phases, let alone the single phase socket outlets. However, for a small
workshop, where there is not likely to be a need to balance loads, that
would be a perfectly acceptable answer.

The request for service is quite adamant about the need to balance
anything and everything. Although as you rightly say, the actual load
here is going to be trivial, they don't have a tick box for that. 8-(

I'm likely to plan for four load groups: 3 phase machinery, hard-wired
single-phase machinery on one phase, sockets on another and lighting
on the third. I certainly don't fancy mixing the sockets across
phases, nor do I see any real need to. Lighting load isn't big enough
to require it. The biggest realistic issue would be splitting the few
simultaneous loads like the compressor (hard-wired) and a plasma
cutter (socketed single-phase) onto separate phases. Worst case
otherwise is single-phase dust collector and single-phase sawbench
both being on the same phase (hard-wired singles) and likely to be
used together, but they're both only =15A loads and I wouldn't plan
to start them simultaneously.

HSE aren't involved, but there will be isolators and NVR as usual
practice.

On 20 Oct, 23:24, "nightjar" cpb@insert my surname here.me.uk
wrote:
"Andy Dingley" wrote in message

There's also the issue of the workshop being near to, but separate
from, the house itself. Some "workshop" "sheds" are inbetween them
(connected to the house, if anything). One of them is a place I'd
particularly like to have robust sockets (physically and electrically)
to drive welders. What are the issues about supplying this either from
the house or the workshop incomers?

Make sure it is from one or the other, but not both, to avoid the
possibility of having some circuits live when you think the supply has been
isolated.

Is there a formal definition of "it" in the regs? The main workshop
and garage is free-standing and has the 3 phase entry through the rear
of it. There's another workshop which is "attached" to the house (via
a row of outbuildings) and that's where I'm likely to want to weld.
Now for the effort of running SWA under the concrete path, I'm happy
to power this entirely from the workshop 3 phase and can easily have
physical separation of a wall, exterior door or 6' spacing between
that and any house-fed outlets. However this would mean I'm running
two supplies into one connected "building" and I was wondering if that
was the point that "nearby" would be regarded as starting to apply.


As already mentioned, you also need to decide whether you are
going to export the earth or have a local earth.

Not sure on that either. I'm not thinking about local earths so much
as the two separate ones supplied by the 'leccy board, entering from
different directions (and quite likely, different substations). Do
these need to be deliberately bonded, deliberately isolated or what?

Andy Dingley coughed up some electrons that declared:

On 20 Oct, 23:24, "nightjar" cpb@insert my surname here.me.uk
wrote:

As already mentioned, you also need to decide whether you are
going to export the earth or have a local earth.

Not sure on that either. I'm not thinking about local earths so much
as the two separate ones supplied by the 'leccy board, entering from
different directions (and quite likely, different substations). Do
these need to be deliberately bonded, deliberately isolated or what?

The first thing to do is to gather some of the pertinent parameters:

If any earth were to be exported to a particular building, it would usually
be the one from the associated supply to that building, but see below...

If I understand you correctly, the 3 phase supply head and meter are in the
garage/main workshop and the house has it's own supply. I guess the main
workshop would best rely on the 3 phase supply's earth - but wait for some
more opinion. It's certainly the more straightforward case.


And you plan to continue this 3 phase supply onto the workshop hanging on
the side of the house?

Do either of the workshops have a lot of exposed metalwork that may carry an
earth potential (framing for example)? How far apart, roughly, are the two
workshops?

What type of earth are on your two supplies: TN-S or TN-C-S? Or are either
TT (other than TT, this needs to be done by enquiry, looking at the supply
head isn't a reliable method, unless it's actually labelled - my supply is
TN-S but looks exactly like a TN-C-S takeoff).

*** This is important *** Is there any metalwork (pipes etc) that goes
between the house and the workshop connected to the house? This is were it
gets hairy, because the metalwork will be introducing the house earth
potential to the workshop and vice-versa.

If so, I bow out - I have no idea how to handle this, other than to TT
everything, house included and add 100mA time delayed RCDs as required. I
wouldn't go bonding two different supply earths together (especially if
they may come from different substations) without getting more informed
opinion and it's way beyond me.

I think most of the questions I've raised are relevant, so the answers may
help someone more informed to offer advice.

Cheers

Tim

"Dave Plowman (News)" wrote in message
...
In article ,
nightjar cpb@insert my surname here.me.uk wrote:
Could you not keep all the GP sockets and lighting on one phase -
given in most of this sort of workshop the majority of the load will
be hard wired?

I'm used to factories where the lighting load needs to be balanced
across phases, let alone the single phase socket outlets.

Yes - I can see that. But in a large building it would be fairly easy to
group stuff to minimise the risk of having adjacent outlets on different
phases?

In one factory I had, the vast majority of single phase sockets served a row
of individual work benches along one wall. As the benches were 1.8m long, it
was necessary to have a couple without sockets - fortunately not difficult,
as they carried hard-wired machinery used by all the instrument makers..

Colin Bignell

"Tim S" wrote in message
...
Dave Plowman (News) coughed up some electrons that declared:

In article ,
Andrew Gabriel wrote:
Wiring regs used to allow 16A sockets on circuits fused at up
to 20A. I don't have any wiring regs handy at the moment to
check the current status.

None of these are shuttered, so they can't be used around the
home. (If you still do, make sure they're positioned well out
the reach of children.)

Many have a heavily sprung loaded cover for when there's no plug inserted
- and that would defeat most small children. They've taken skin off me
before now. ;-)


And you can get ones with an interlocked isolator - I rather fancy a
couple
of these on the side of my house.

Very annoying when you forget that they are interlocked and try to pull the
plug out.

Colin Bignell