240 General: New (to me) 1980 Volvo 244

[Stephen Edwin]

Actually. I did a typo. oops.


.

[Othen]

Originally Posted by Laird Scooby

It sounds like the original sparky has made more than one mistake thre Alan! Needs his ar5e kicked in fact!
Why did he kink it round a gate knowing it's likely to get whacked by the gate? Should have run it above the gate on a catenary wire.

I assume it's a radial circuit and not a ring, hence the 16A breaker? Do you have or are you likely to have a welder in the garage? If so i'd strongly recommend replacing it with 4mm 3-core SWA, running it as a catenary wire support to minimise accidental damage and upgrade your MCB to a Type C 32A breaker to cover the welder.

As a general rule of thumb, any sharp bends are a big no-no with SWA and it's good practice to make a drip-loop below the cable entry point to the building.

I have done some research on this Dave.

Unfortunately the minimum height for a catenery would be 3 m (table D2 of the OSG) - and that would be inside a steel conduit. The garage's gable end is above that height, but it would make the span about 3 m (rather than 3' to the eves, at 2.2 m) - so I think it would look a little bit daft. That is a pity - I'd convinced myself it would be worth doing the work to change to a 4mm^2 cable (and if I ran it through conduit instead of SWA I would get 32A to the garage).

Many thanks for the idea - it was very close to working :-)

[Laird Scooby]

Originally Posted by Othen

I have done some research on this Dave.

Unfortunately the minimum height for a catenery would be 3 m (table D2 of the OSG) - and that would be inside a steel conduit. The garage's gable end is above that height, but it would make the span about 3 m (rather than 3' to the eves, at 2.2 m) - so I think it would look a little bit daft. That is a pity - I'd convinced myself it would be worth doing the work to change to a 4mm^2 cable (and if I ran it through conduit instead of SWA I would get 32A to the garage).

Many thanks for the idea - it was very close to working :-)

Thanks for the update Alan, i've just looked into this as well and it seems the IEE (the people that brought various wiring/installation regs such as 16th Edition) have joined forces with IIE (who i hadn't heard of) and become IET and we're now on 18th Edition for wiring regs.
It seems they've over-complicated things and assume everyone will be riding a horse round their property - height of someone sat on an average horse with an outstretched arm and finger is ~3m - but have ignored the practicalities of running such an installation.

You mentioned before about burying it, that might be a more sensible option, especially with paving slabs over it to further protect it. Check the regs out on that as i've rarely been involved with buried cables so my knowledge is a bit hazy.

I do remember running catenary wires supporting SWA at a certain west London football club to power floodlights about 20 years ago and i'm fairly sure they weren't 3m or higher, more like 2.5m if that. That said they were in an area that wouldn't normally have had pedestrian access or any other form of access. Things change constantly, especially with te wiring regs so there's every chance that while that would have been fine at time of install, some time later it wouldn't. It's like one reg of the IEE regs outlawed metl cased fuseboxes, insisting all new installs had to be plastic. A few years later, plastic fuseboxes/consumer units were outlawed in favour of metal ones! Work that one out!

[Othen]

Originally Posted by Laird Scooby

Thanks for the update Alan, i've just looked into this as well and it seems the IEE (the people that brought various wiring/installation regs such as 16th Edition) have joined forces with IIE (who i hadn't heard of) and become IET and we're now on 18th Edition for wiring regs.
It seems they've over-complicated things and assume everyone will be riding a horse round their property - height of someone sat on an average horse with an outstretched arm and finger is ~3m - but have ignored the practicalities of running such an installation.

You mentioned before about burying it, that might be a more sensible option, especially with paving slabs over it to further protect it. Check the regs out on that as i've rarely been involved with buried cables so my knowledge is a bit hazy.

I do remember running catenary wires supporting SWA at a certain west London football club to power floodlights about 20 years ago and i'm fairly sure they weren't 3m or higher, more like 2.5m if that. That said they were in an area that wouldn't normally have had pedestrian access or any other form of access. Things change constantly, especially with te wiring regs so there's every chance that while that would have been fine at time of install, some time later it wouldn't. It's like one reg of the IEE regs outlawed metl cased fuseboxes, insisting all new installs had to be plastic. A few years later, plastic fuseboxes/consumer units were outlawed in favour of metal ones! Work that one out!

I'd agree there is a bit of daftness in this area - the sparky's forums are always coming up with anomalies.

The minimum height for a catenary has nothing to do with electricity of course, it probably originated in some other bit of the building code.

I think you will be able to see the situation from this photo:



... the alarm would be at about 3m - and at that height the span to the gable end would be up to about 3m, which would be daft.

Buried SWA might be a solution, but I'm not so keen because the route entails two sharp bends, but I think there might be a cunning way around the regulations. I could fit a lintel above where the gate is now - to the eves end at about 2.2m (and so have a garden door instead of a gate - make it look nice with some wood or bricks). There wouldn't be a span between the house and the garage, so I could just run a 25mm conduit above it - clipped so as to give 32A at the garage - and it could be plastic (lighter and cheaper). This sounds a bit contrived - but then the regulation is a bit daft in the first place.

I'll think about it for a while.

Maybe I'm being a bit fastidious about this - the current (excuse the pun) set up works perfectly well, I can even run my Charke MIG welder (came with a 13A plug) without tripping anything (as long as I don't run anything else drawing more than about 3A at the same time). It is only my almost retired arc welder which can cause a problem (and even then only if I turn the current up over half way). It is a pity the builder only used 2.5mm^2 cable in teh first place, but I'm nit sure it is worth trying to rectify that now.

:-)

[loki_the_glt]

Originally Posted by loki_the_glt

I'll get you one with the various dimensions in the next few days - just as soon as I can locate a ruler and some suitable background material.

Fiinally got round to doing this. Attached are a sketch and dimensions for the tool along with some photographs of it.

[Othen]

Originally Posted by loki_the_glt

Fiinally got round to doing this. Attached are a sketch and dimensions for the tool along with some photographs of it.

Excellent - many thanks. That gives me a basis to manufacture something similar for the B21.

Alan

[Laird Scooby]

Originally Posted by Othen

I'd agree there is a bit of daftness in this area - the sparky's forums are always coming up with anomalies.

The minimum height for a catenary has nothing to do with electricity of course, it probably originated in some other bit of the building code.

I think you will be able to see the situation from this photo:



... the alarm would be at about 3m - and at that height the span to the gable end would be up to about 3m, which would be daft.

Buried SWA might be a solution, but I'm not so keen because the route entails two sharp bends, but I think there might be a cunning way around the regulations. I could fit a lintel above where the gate is now - to the eves end at about 2.2m (and so have a garden door instead of a gate - make it look nice with some wood or bricks). There wouldn't be a span between the house and the garage, so I could just run a 25mm conduit above it - clipped so as to give 32A at the garage - and it could be plastic (lighter and cheaper). This sounds a bit contrived - but then the regulation is a bit daft in the first place.

I'll think about it for a while.

Maybe I'm being a bit fastidious about this - the current (excuse the pun) set up works perfectly well, I can even run my Charke MIG welder (came with a 13A plug) without tripping anything (as long as I don't run anything else drawing more than about 3A at the same time). It is only my almost retired arc welder which can cause a problem (and even then only if I turn the current up over half way). It is a pity the builder only used 2.5mm^2 cable in teh first place, but I'm nit sure it is worth trying to rectify that now.

:-)

Change your MCB for a Type C, that deals with inrush current better than a Type B, you said you had a B20 MCB if memory serves? Change it for a C20 (or whatever rating after you've upgraded the wiring) and that will cope with the welder.
If you have any big motors that you might run (such as a large compressor) change the breaker for a K type as that is motor rated. Either still protects against prolonged over-current but is more resilient to inrush current (matter of mS) for the motor (or welder) start up.

That said if your propsed move to Norfolk happens, don't bother with anything once you've repaired the existing SWA cable!

[Othen]

Originally Posted by Laird Scooby

Change your MCB for a Type C, that deals with inrush current better than a Type B, you said you had a B20 MCB if memory serves? Change it for a C20 (or whatever rating after you've upgraded the wiring) and that will cope with the welder.
If you have any big motors that you might run (such as a large compressor) change the breaker for a K type as that is motor rated. Either still protects against prolonged over-current but is more resilient to inrush current (matter of mS) for the motor (or welder) start up.

That said if your propsed move to Norfolk happens, don't bother with anything once you've repaired the existing SWA cable!

Thank you for that idea Dave,

The power circuit is a B16 at the moment, but I've just checked in the book and I could legitimately change that for a 20A (so C20), which would give me a little more headroom for the MIG welder (the compressor is quite small and has not been an issue).

As you know - we are thinking of moving to Norfolk/Cambridgeshire - so there probably isn't much point investing all that much time and money until we decide what we are doing. I've fixed the SWA - if I can find a C20 MCB to fit the garage CU that would be enough for the time being.

It is a pity about the catenary issue - if it hadn't been for taht I could have done the whole upgrade to 4mm^2 cable for about £60 and half a day's work.

:-)

PS. DZ47 format MCBs (ideally CGD) seem to be obsolescent.

[Laird Scooby]

Originally Posted by Othen

Thank you for that idea Dave,

The power circuit is a B16 at the moment, but I've just checked in the book and I could legitimately change that for a 20A (so C20), which would give me a little more headroom for the MIG welder (the compressor is quite small and has not been an issue).

I've fixed the SWA - if I can find a C20 MCB to fit the garage CU that would be enough for the time being.

It is a pity about the catenary issue - if it hadn't been for taht I could have done the whole upgrade to 4mm^2 cable for about £60 and half a day's work.

:-)

PS. DZ47 format MCBs (ideally CGD) seem to be obsolescent.

Is this the animal Alan?

https://www.ebay.co.uk/itm/1-Pole-20...0/362590744785



Nice and cheap upgrade if so!

[Othen]

Originally Posted by Laird Scooby

Is this the animal Alan?

https://www.ebay.co.uk/itm/1-Pole-20...0/362590744785



Nice and cheap upgrade if so!

How do you keep doing that Dave? I look for an item, fail miserably, tell you and 5 minutes later I have a link to it.

The MCB is ordered (right form factor, should fit straight onto the buzz bar); coming from HK so I suppose it will be here in about 3 weeks, but I've lived with the old set up for 11 years so that is no great problem.

Thank you my friend.