Cam switch, help please

[Gulfsailor]

Hi electrical gurus.

I want to connect a 32A oven and a 20A water heater (both single phase 220V, grounded) to an unused group. The appliances will be around 15 meters from the fuse box. I only have a 15/45 meter and a main breaker of 63A with a separate Safe t cut in front also 63A.

Due to limitations on electric I decided not to use oven and heater at the same time. So my idea to run a 3x4mm2 insulated wire from the fuse box to a cam switch, where it provides power to either oven or heater. I purchased the only big cam switch I could find locally, rated 63A, but better to big than too small I reckon.

Is there any expected problems with above setup?

And then my main question; how to hook up the can switch. I should have 3 wires going in (L-N-E) and would like 0 setting shut power off to both appliances, whereas on setting 1 I'd like only the oven to have power and on setting 2 only the heater. So 2 time three wires should come out. Attached pictures of the cam switch and the diagram instructions which are totally abracadabra to me.

Thank you!

[bankruatsteve]

You don't need to carry the earth through the switch, or the neutral for that matter. I would try to return the switch and run 6mm2 wire to both the oven and the heater on a 32amp breaker.

[Gulfsailor]

You don't need to carry the earth through the switch, or the neutral for that matter. I would try to return the switch and run 6mm2 wire to both the oven and the heater on a 32amp breaker.

Thank you. But I need to cut the insulated triple wire anyway. I can use a cap to connect the neutral and earth again but I may as well use the screws on the switch if that's possible.

As for connecting both appliances together without a switch, I think that's asking for trouble. The oven is 6400 W and the heater 4500 W. So together over 50A. I don't want that on one group. And I never have to use the appliances together anyway.

[Crossy]

OK. Under no circumstances switch the earth.

That switch is wired as a 3-phase reversing switch, first remove all the links then you will be able to check which contact pairs are connected in each position using your multimeter / bulb and battery.

You should be able to re-use the links to provide the common (input) connection.

[bankruatsteve]

Well, you're the boss - but there is no problem putting multiple high-draw devices on one circuit as long as you consider the maximum draw. That must be one hell of an oven! BTW: if it does actually draw 6.4KW, that would be over-spec for 4mm2 (according to Crossy's chart). I would still go with 6mm2 and 32a breaker (with no inconvenient switch) and guessing it would never trip even with both units in use.

[Crossy]

4mm² VAF will (just) be OK on a 32A breaker if it's in free air.

Applying diversity for the oven and assuming the water heater is only used for showers it will be fine.

I would just run both appliances on the same cable, if you accidentally turn both on all that will (may) happen is that the breaker will open.

Don't over think the issue, but if you want to use the switch no problem, see my previous post.

[bankruatsteve]

Just to add - putting a switch between those two for "protection" just doesn't make sense. The breaker will do that for you - if, and probably never when, that would be an issue. Your oven, at 6400W must have that at 2-3 elements which would almost never be used in total - or maybe you have special cooking requirements?

BTW: what brand oven is that and where did you get it? Got to say, I've never seen one available here with that spec.

[Gulfsailor]

Just to add - putting a switch between those two for "protection" just doesn't make sense. The breaker will do that for you - if, and probably never when, that would be an issue. Your oven, at 6400W must have that at 2-3 elements which would almost never be used in total - or maybe you have special cooking requirements?

BTW: what brand oven is that and where did you get it? Got to say, I've never seen one available here with that spec.

Thank you and Crossy for the feedback.

The setup is for a semi professional kitchen. The oven is 2 fan convection with steam function. Google YXD-8A. Sold OEM from different suppliers/brands. There is a 380V 3 phase version and a 220V version. Since I don't have 3phase I will purchase the 220V one.

The heater is used to heat water going to a spray faucet to clean dishes. I just installed a 4500W cheapo, but if it won't do the trick in supplying hot enough water at high enough pressure I will switch to a stronger one, which could also be over 6000W.

When baking bread or pastry, there is no cleaning to do, so no need to run them simultaneously. I can't risk the oven turning off due to breaker flipping when someone accidentally opens the faucet when the oven is running. The setup should be idiot proof.

Now back to the switch. I took the bridges out and multimetered the thing. The results are:

In position 0, connected are;

3-R

7-S

11-T

12-W

Others are not connected (2, 8, U, V)

In position 1, connected are:

2-3-R

7-8-S

11-12-T-W

Not connected U and V

In position 2, connected are:

3-R-U

7-S-V

11-12-T-W

Not connected 2 and 8

So may brain came up with this;

Incoming:

L to 3

N to 7

E to 11

To oven (pos1):

L to 2

N to 8

E to T

To heater (pos2):

L to U

N to V

E to T

That way switch only switches Live and Neutral and earth is always connected to both appliances even in pos0.

Comments are more than welcome!!! Thanks.

[Crossy]

Did you remove the links before making those measurements?? Assuming you did then that should be OK.

But check, check, check once it's connected up. A battery connected as mains and two bulbs (oven and heater) will allow you to verify nothing is untoward before applying power.

I note you're using T / 11 as a marshalling point for the earth, personally I would separate the earth completely from the switch (use a big choc-bloc) just in case it causes confusion later.

One major rule of engineering, "Make something idiot proof and someone will develop a better idiot".

EDIT By the way, where did you get that switch and how much was the beast. It could form the basis of a nice low-cost generator transfer switch.

[IMHO]

EDIT By the way, where did you get that switch and how much was the beast. It could form the basis of a nice low-cost generator transfer switch.

Indeed! I still haven't ordered mine either - so curious

[Gulfsailor]

Did you remove the links before making those measurements?? Assuming you did then that should be OK.

But check, check, check once it's connected up. A battery connected as mains and two bulbs (oven and heater) will allow you to verify nothing is untoward before applying power.

I note you're using T / 11 as a marshalling point for the earth, personally I would separate the earth completely from the switch (use a big choc-bloc) just in case it causes confusion later.

One major rule of engineering, "Make something idiot proof and someone will develop a better idiot".

EDIT By the way, where did you get that switch and how much was the beast. It could form the basis of a nice low-cost generator transfer switch.

Hi Crossy. Yes I removed the links before measuring. Good idea to first test with a battery and some light bulbs. Will do that. The box the switch will be in has space enough, so will do as you suggest and connect the Earth using a block.

I found the switch in a local electric store on Samui. Brand name of the switch is Shinohawa. They had a big catalogue which listed a lot more types, but they only stocked smaller ones and this 'beast'. At 1300 Baht it wasn't too bad.

Incidentally I also thought this switch would make a perfect solution with a generator. Instead of 1 in 2 out, use it to switch 2 in 1 out.

Thanks again!

[IMHO]

I found the switch in a local electric store on Samui. Brand name of the switch is Shinohawa. They had a big catalogue which listed a lot more types, but they only stocked smaller ones and this 'beast'. At 1300 Baht it wasn't too bad.

One of these I assume?

http://www.thaieee.com/db/pages/Page%20(13).pdf

[Gulfsailor]

I found the switch in a local electric store on Samui. Brand name of the switch is Shinohawa. They had a big catalogue which listed a lot more types, but they only stocked smaller ones and this 'beast'. At 1300 Baht it wasn't too bad.

One of these I assume?

http://www.thaieee.com/db/pages/Page%20(13).pdf

You assume correct. The box displays a number that is not in that list. But someone wrote with a pen very small AS402 on the box which is in the list I see. I don't know what's special about it as the description is in Thai. But as said that was the only switch over 20A that the stocked, so I just purchased it. At 1300 baht it seems a good deal compared to list price of 1900.

[Crossy]

The AS402 is described as a "Reversing switch, 3-phase, 25 horse, 63A, panel marked 1-0-2"

[Gulfsailor]

The AS402 is described as a "Reversing switch, 3-phase, 25 horse, 63A, panel marked 1-0-2"

25 horse? Cool.