I have a wiring issue regarding the wiring center......

In Figure 1, the wiring diagram shows that the cables of the thermostat should be connected from the top, but in actual wiring (Figure 2), they are connected from the bottom. What I mean is that there are two rows of terminals (one at the top and one at the bottom), and the terminals at the bottom should logically have the cables connected from below. Why are the terminals at the top also connected from below? (I understand that for this device, the slots for securing the cables are all at the bottom, so all the cables need to be routed from below. Why aren't there slots at the top?)

Given it's a wiring centre for water based heating, it's likely it will be being installed somewhere inappropriate by a plumber who doesn't mind how wet things get. By restricting cable entries to the bottom of the enclosure, if the top edge is well designed you can minimise the chances of water ingress and the consequential damage/expense of having someone come out if it gets leaked on.

SparkyChick said:

Given it's a wiring centre for water based heating, it's likely it will be being installed somewhere inappropriate by a plumber who doesn't mind how wet things get. By restricting cable entries to the bottom of the enclosure, if the top edge is well designed you can minimise the chances of water ingress and the consequential damage/expense of having someone come out if it gets leaked on.

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Thanks, I also heard some answers like this, but I noted that nearly all these kinds of devices' IP are IP20, it is not waterproof, so, it can not avoid protection damage even if the cables are connected from bottom......

Just to be clear... just because something is IP20 does not mean it can't be designed to minimise the chances of damage if water were to leak on top of it or run down the wall behind it. It's actually pretty straightforward to do with some simple design tricks and carefully selected installation materials.

I am available for consultations on such matters, I can provide my day rate for such endeavours if you require

SparkyChick said:

Just to be clear... just because something is IP20 does not mean it can't be designed to minimise the chances of damage if water were to leak on top of it or run down the wall behind it. It's actually pretty straightforward to do with some simple design tricks and carefully selected installation materials.

I am available for consultations on such matters, I can provide my day rate for such endeavours if you require

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Thank you very much for your explanation. Not for now, I am just curious about the design. But I think we will have the opportunity to cooperate in the near future. Can you give me your email address? It will be more convenient to contact you when I need some paid cooperation.

i think figure 1 is just a block diagram showing what can be connected... up/ down... it doesnt matter.....
fig2 shows the interior... showing all the flex cable routes are out the bottom only... there are no cable entry holes in the top.

If there were also slots and cable restraint at the top the whole unit would be larger, that's the base and the cover and be more expensive to produce.
Yes it may only be a few pence / cents but that's an important element for manufactures.

The base / cover may also be used for other models of wiring centre and used by many manufacturers.

as @SparkyChick says, it is not difficult to make an enclosure that is sealed to IP66 standard from above and have holes in the bottom.
(IP66 is high pressure water jets from any direction for 3 minutes with no ingress of water)
because it has holes in the bottom it could not meet IP66 because a jet from below would cause it to fail the test.

In real life water rarely jumps up into enclosures, it has a habit of falling down into them (blame newton for that one)
and unless I am installing something where the water level may rise and put it underwater or there are in fact jets of water from any direction hitting it, I would always drill a drain hole in the bottom of any sealed enclosure.

the problem with sealed enclosures are, if you get any moisture inside it, it cant escape so if there is even a drop of water getting inside once a week, eventually it will fill up and damage whatever is inside.