Designing with Ease-of-Maintenance in mind?

[JohnW2]

Whatever, please don't slide this (potentially interesting, at least to me) thread off on a tangent which could easily lead to 'thread degeneration', because I'm getting pretty sick of the manner in which you so often ruin potentially interesting threads in that way!

And I'm getting pretty sick of the manner in which you think it's OK for you to introduce something into the discussion and then try to impose limitations on what other people may write in response.

Fair enough. If anyone wishes to discuss the question of the extent to which manufacturers design with ease-of maintenance in mind, they can do so here.

Kind Regards, John.

 

[holmslaw]

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[JohnW2]

Whats the point, generally speaking electrical installations don't require any maintenance.

It was 'maintenance' in a broad sense that brought this discussion about - specifically, issues of inspection/testing and possibly changes/additions to the installation.

Kind Regards, John.

 

[bernardgreen]

I have seen a lot of bias in design towards making the intallation and testing of the installation easier at the cost of making the system fit the function.

Car bodies being built around the engine rather than the engine being lowered into the finished body is ideal for manufacturing but a massive disadvantage for repairs to the engine. A car is for getting people from place to place and if it breakdown on route it should not be that almost all engine problems other than basic battery related problems need workshop equipment. Today we have too many car users and too few motorists.

One example in electrics is some people prefering radials over ring finals simply because a radial is easier to test thus making "manufacture" easier. It also makes the guidelines for testing by cable installer easier to write. Today we have too many cable installers and too few electricians.

 

[bernardgreen]

I have jsut read this from Ban All Sheds

That's utter nonsense - manufacturers make strenuous efforts to design products in a way which makes them easier to maintain because that makes them cheaper to maintain and therefore gives them a lower TCO, which is a competitive advantage.

Read more: http://www.diynot.com/forums/electr...circuits.300658/#2194701#ixzz1eYUmQGq[/QUOTE]

Many manufacturers do not consider maintainance at the design stage.

Some simply do not think about it.

But some intentionally make the equipment difficult to maintain in order to sell more equipment as replacements or to lock the customer into an expensive service system when repairs are necessary.

 

[JohnW2]

I have seen a lot of bias in design towards making the intallation and testing of the installation easier at the cost of making the system fit the function.

Indeed.

One example in electrics is some people prefering radials over ring finals simply because a radial is easier to test thus making "manufacture" easier. It also makes the guidelines for testing by cable installer easier to write. Today we have too many cable installers and too few electricians.

Indeed - which is why, in the thread which spawned this one, I said that difficulty of subsequent testing/maintenance/modification should probably not be a reason for not having 'bridged' ring final circuits, if the idea were otherwise regarded as sound, perhaps even desirable, in engineering terms.

Kind Regards, John.

 

[Paul_C]

Many manufacturers do not consider maintainance at the design stage.

Some simply do not think about it.

And, sadly, when it comes to most of the cheap junk of consumer electronics coming out of Red China, maintenance doesn't figure into the equation at all, because the manufacturer knows that it's simply never going to be maintained. When it goes wrong, it will just be scrapped completely because there's no way that any attempt at repair could ever be justified on economic grounds.

 

[securespark]

Just adopt the Middle Eastern approach...

When the ashtray's full, ditch the car.

When a fuse blows, build a new house.

Simples!

 

[ban-all-sheds]

So on the one hand we have this:

difficulty of subsequent testing/maintenance/modification should probably not be a reason for not having 'bridged' ring final circuits, if the idea were otherwise regarded as sound, perhaps even desirable, in engineering terms.

and on the other we have people criticising designers for creating things which are difficult to maintain.

"Maintenance" of electrical installations isn't really regular oiling of cables and adjusting clearances of switch contacts, it's adapting it to meet changing requirements.

And I think it is definitely right and proper, and good engineering, to make ease of doing that one of your criteria.

 

[JohnW2]

So on the one hand we have this:

difficulty of subsequent testing/maintenance/modification should probably not be a reason for not having 'bridged' ring final circuits, if the idea were otherwise regarded as sound, perhaps even desirable, in engineering terms.

and on the other we have people criticising designers for creating things which are difficult to maintain.

Indeed - although I think that last bit should actually read "...people criticising designers for unnecessarily and/or deliberately creating things which are difficult to maintain".

In other words, whilst consideration of 'maintainability' should be an important part of the design process, ease of maintenance should not be used as a reason for making a product less fit for purpose, less safe or whatever (an obvious example would be the ommision of safety guards etc.). In terms of the context in which this arose, if, hypothetically, people (particularly the IET) were to buy into the idea that a ring final with bridges was actually safer than one without bridges (I'm not holding my breath for that to happen!), then I don't think they ought to refrain from recommending it simply because of the difficulties of maintenance it could result in.

In essence, convenience should not be given priority over safety, nor necessarily even over functionality (in some cases, reduced convenience may be regarded as an acceptable price to pay for optimal functionality).

That's how I see it, anyway. Others will undoubtedly disagree.

Kind Regards, John.

 

[holmslaw]

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[JohnW2]

I still don't understand the perceived problem. A properly trained and experienced electrician will have no problem doing any of those things.

It sounds as if you have not seen th thread which spawned this one - and it was not me that introduced this 'perceived problem' (which I accept would certainly be an inconvenience) .... the suggestion was that, far from being 'a problem' which needs to be rectified, it can be argued that 'bridges' in ring final circuits actually offer benefits. Whilst no-one has (so far!) been able to fault the logic of that suggestion, it was pointed out that the resultant 'mess' would make testing and modification of the resultant circuits more difficult. There wasn't actually any suggestion that a properly trained and experienced electrician would be unable to cope with this, merely that it would increase the amount of time and effort (hence cost) involved.

Or are you thinking along the lines, that installation designs should be made simpler to equal the inadequacies of a modern 'trained' electrician.

You are the first person to have made that suggestion in this discussion. Whilst one has to have some sympathy with what you say, to 'simplify the designs' rather than train electricians properly would obviously be a less-than-ideal solution to any perceived problem of this type!

Kind Regards, John

 

[EFLImpudence]

In terms of the context in which this arose, if, hypothetically, people (particularly the IET) were to buy into the idea that a ring final with bridges was actually safer than one without bridges (I'm not holding my breath for that to happen!), then I don't think they ought to refrain from recommending it simply because of the difficulties of maintenance it could result in.

I'm beginning to wonder what exactly you think may be the outcome of 'recommending' bridges.
Obviously, It would make the shorter ring, created by the bridge, less unbalanced and the sockets within that shorter ring better protected but to what end?
Would we be limited to one per ring or as many as we wanted - ending up with the new 'Ladder Final Circuit'?
It would appear to be making safer things which were satisfactory already or only a means to counteract an initial poor design.

Perhaps every socket on a ring should have another cable connected to it returning directly to the CU.
There are many things that could be done but they would just be pointless and a waste of cable.

Your suggestions, although logical, would seem to be better served by initially designing radial circuits.

 

[JohnW2]

Athough this should really be in the original thread ....

I'm beginning to wonder what exactly you think may be the outcome of 'recommending' bridges.

As you know, I have never recommended, or suggested that anyone should recommend, bridges. I merely asked why it was that everyone seems to regard bridges as 'a problem' when, as far as I could make out (by application of engineering logic), a ring with bridges is no less safe than one without bridges (and, indeed, on the contrary, it seemed to me that the existence of bridges would tend to have beneficial, rather than detrimental, effects). You are about the only person who actualy answered my question - and your answer was that you could not fault my logic - but you did add that the 'mess' would create inconvenience in terms of testing and circuit modification.

Obviously, It would make the shorter ring, created by the bridge, less unbalanced and the sockets within that shorter ring better protected but to what end? Would we be limited to one per ring or as many as we wanted - ending up with the new 'Ladder Final Circuit'? It would appear to be making safer things which were satisfactory already or only a means to counteract an initial poor design.

As above, I was not suggesting/recommending - merely asking why it actually seemed to be regarded as 'a problem', perhaps even 'dangerous',since I couldn't understand why that was the case.

... and no-one has yet answered my question as to how (if at all) electricians would 'code' a bridge which they detected, and what parts of BS7671 they would cite in support of that coding.

Kind Regards, John.

 

[EFLImpudence]

I merely asked why it was that everyone seems to regard bridges as 'a problem'

I would say because it makes testing difficult.

... and no-one has yet answered my question as to how (if at all) electricians would 'code' a bridge which they detected, and what parts of BS7671 they would cite in support of that coding.

There is a reason for that, as you well know.

Obviously, if coded at all, it would have to be the new C3.
However, if after asking on here for the appropriate regulation and ten pages later no regulation has been found then we would deduce that it did not need coding (or was not able to be coded).

Or, if after such a problematic test procedure, would the electrician not just remove the bridge?