Replacing a 3 phase oven

[sparkol]

Hi. I’m a spark with plentyof experience of domestic single phase but not much commercial, and 3 phase isjust a distant memory from college.
I have a customer who wants a 3-phase oven replacing. It’s on a suitable circuit with all-poleisolator so it should just be a simple like-for-like swap. I’m just slightly intimidated by the fact it’s3-phase and wondering whether there’s any traps to watch out for.
For example, the existing supply flex has two black coresand one brown for the three lives. Is itpossible to mix the phases up or are L1, L2 and L3 interchangeable? My understanding is that ovens normally justuse a single phase for each element so presumably not.
So, what I’m asking is, is this a simple straight swap or shouldI give it a swerve and stick to what I know?
Thanks

 

[Plonker 3]

Read the instruction manual when the new one arrives. That will tell you a lot more than we can about something we have no information on.

 

[sparkol]

Thanks, will do.
But what I need to know now, at this point in time, is that IF I agree to swap this oven can I be fairly confident it will be five wires out and five wires in, and I won't get stuck and leave the customer with no oven? I'm sure you can see where I'm coming from.

 

[Plonker 3]

Well unless there are any external controls to wire, then yes it should be a straight swap. Have you googled the make and model for the oven instruction manual, or even asked the customer for it?

 

[sparkol]

Yes I've found the manual and indeed it looks like a straight swap. I know this was a slightly weird post but I'm just trying to be cautious because its outside my comfort zone. The manual says nothing about which phase does what. Is there any danger involved in interchanging phases or does it not matter?
Thanks for your help.

 

[Plonker 3]

Can't think so, it shouldn't run backwards lol.

if you aren't confident then I would say don't take he job on.

If you do decide to do it then just mark which cable goes to which terminal. Reconnect as was turn on and see if it works.

 

[sparkol]

Great stuff, thanks

 

[snowhead]

If it's a large oven it may have a 3 ph fan motor and 3ph elements.
The fan direction will be marked in the casing.

Otherwise everything will be single phase spread across phases.

 

[ian.settle1]

Can't think so, it shouldn't run backwards lol.

if you aren't confident then I would say don't take he job on.

If you do decide to do it then just mark which cable goes to which terminal. Reconnect as was turn on and see if it works.

What if it has a 3 phase fan fitted

 

[Plonker 3]

Good point, but would like to think the OP will read the destructions first and understand what's involved if phase rotation is incorrect.

 

[telectrix]

just be logical and above all, safe isolation,.

 

[Resu]

You shouldn't be worried about confusing which wire is which phase. If they aren't already, you could mark them by belling out the switch wire surely?

 

[thebigcheese]

The only thing that has caught me out before is that only 4 wires - L1,L2,L3 and an Earth have been run out (as Neutral isn't always used on 3ph equipment). You mentioned seeing the 3 phase wires but was there a neutral too?

 

[GLENNSPARK]

test in low ohms between L1, L2 & L3 coming in...with switches on....if its open then its 3 single phase loads....isn`t it...

 

[GLENNSPARK]

it should be marked up as well in the back of the oven where the connection enclosure is L1 L2 L3....

set tester to phase rotation and test incoming to verify whats what....