Is it just me, or have Wylex made a blunderous error?!

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davesparks

• Apr 14, 2015

• #2

Id ask Monsieur Foucault about that one!

 

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davesparks

• Apr 14, 2015

• #3

I guess it's not been a problem as the current actually flowing through that link will be pretty low. Plus the phenomenon to which you are referring doesn't really manifest itself at currents under 200A

 

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ipf

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• Apr 14, 2015

• #4

Did it come with blue heat shrink and gun ?
:4:

 

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sparkdog

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• Apr 14, 2015

• #5

Like the gloves.

 

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D Skelton

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• Apr 14, 2015

• #6

sparkdog said:

Like the gloves.

Click to expand...

It's a cast lol

 

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Darkwood

• Apr 14, 2015

• #7

Looks cheap and tacky...

Not sure on this one - very poor design with lack of sheath to the rear ... an area you may run your cables thus easy to accidently create a N/E issue.
As for Eddie and his currents...hmmmm a good point, as you have only the N passing through the slots I can't see how it would create an eddie current large enough, if it had one or more phases passing through separate slots/holes then you have a possible circulating eddie current path...

 

Last edited by a moderator: Apr 15, 2015

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Lucien Nunes

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• Apr 14, 2015

• #8

Current is current, no matter which conductor is carrying it. I'd call it poor design but as mentioned I bet it doesn't notice in normal use with mixed loads. Neutral currents can be unusually high in some applications, such as theatre lighting, because loads are often heavily unbalanced. Under some conditions they can even exceed phase currents due to the 3rd harmonics which add in the neutral rather than cancel. Would be interesting to know if they did tests to prove it wasn't a real problem...

 

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davesparks

• Apr 14, 2015

• #9

I can't see a problem with the insulation of the bar, all Wylex boards of that age use that same enamelled copper bar and I've not heard of any problems with it. It's the same bar they use for the live in their 100A single phase sw fuse.

 

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Geordie Spark

• Apr 14, 2015

• #10

D Skelton said:

It's a cast lol

Click to expand...

I was thinking that hand looks too clean to belong to an honest hard-working man. :laugh:

 

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Darkwood

• Apr 14, 2015

• #11

Also to note here is the cable has no metallic sheath so Sheath currents will not be an issue which is one big influence of the eddie current effect especially enforced if grounded by metallic glands to the steel plate although not grounded won't stop the issue .... I'm on the 'It should be ok' camp on this one tbh at these low currents and lack of sheath currents too.

I've only ever had Eddie current issues on jobs I've been to if the single core cables were metal sheathed or in steel conduits and then even small loading can see significant heating.

 

Last edited by a moderator: Apr 14, 2015

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Darkwood

• Apr 14, 2015

• #12

davesparks said:

I can't see a problem with the insulation of the bar, all Wylex boards of that age use that same enamelled copper bar and I've not heard of any problems with it. It's the same bar they use for the live in their 100A single phase sw fuse.

Click to expand...

If thats just a see through insulating laquer then Ill retract my concerns over the N/E issues.... I always use Scheider gear and a lot better by design.

 

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Darkwood

• Apr 14, 2015

• #13

Reet had a good think and look at the pics and we all have missed the obvious..

In order to create an Eddie Current you will need to have a flow and return between 2 x AC current carrying cables entering through separate glands/holes where a closed loop between glands can exist, looking at the picture the 3phases will be as expected totally insulated from all other metalwork except its busbar and pins. This means the N going through the back plate is of no concern regardless of its loading etc.

Eddie currents are more pronounced and expectant on metal sheathed single core cables as you get sheath currents induced.
Grounding of this sheath through a ferrous metal plate with say a gland or conduit will re-inforce the issue.
Eddie currents can flow not just between two adjacent glands but any situe where a closed loop has been created to allow the eddie currents to flow.

Thats how I see it ... now when looking at much bigger currents >200amps say you may get problems regardless of a metallic sheath or conduit, also very large currents and even Non ferrous metals can circulate Eddie currents.. but I'll leave that those that deal with the big stuff.

 

Last edited by a moderator: Apr 14, 2015

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davesparks

• Apr 14, 2015

• #14

But the neutral passes through the plate twice, with the current effectively going from front to back the first time and back to front the second time.

 

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Silly Sausage

• Apr 14, 2015

• #15

davesparks said:

But the neutral passes through the plate twice, with the current effectively going from front to back the first time and back to front the second time.

Click to expand...

There'll be a caveat in the instructions somewhere, "Only to be used on a near balanced system".

 

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