Quick Question (16mm singles cable)

[kev123]

Hi, help required.

Control panel with a 125A 60947-3 main isolator feeding internal 16mm singles cable to a 80A M.C.B believed to have been originally 100A rated, a previous electrician removed this and down rated to 80A. This then in turn supplys internal control gear ( contactors, relays etc etc. )

The problem

The temp in the panel is 60 degrees plus i measured the 16mm singles between 66 and 67 degree celsius. Maximum demand has not been established but should not exceed 100A.

Am i safe to say that in this situation according to cable ratings they are rated at 67A? if so would i be correct in saying that if i were to swap with 25mm or 35mm singles then also revert back to a 100A M.C.B this would be problem solved? I have suggested that the temperature needs to be reduced so as not to add to the problem.

Thanks Kev

 

[Engineer54]

Is this 60 deg temperature within this panel constant, and what is the surrounding ambient temperature??

You really need to establish what the maximum demand of this panel is, you can get a very good idea of that value by connecting a recording amp-meter or power analyzer over a 24 hour (or longer) typical period... You can then check panel as a whole, and further test periods on individual circuits. These bits of test kit can be expensive, depending on the parameters the kit can measure or calculate.

A basic 3 phase recording amp-meter will be around 500 to 600 quid, but can go several times that figure. Any decent manufacturing industrial company should have such test kit, or not present objections to obtaining one. They are invaluable to such companies as they can also save money and down times to such industrial processes etc!!

Once you have the information you need, you can assess the methods/actions needed to reduce the high temperatures within this panel. You may in the worst instance, need to install thermostatically controlled panel fan(s)

 

[kev123]

Cheers, temperature is constant all year round.

My theory is to install intake and extract fans as too reduce the ambient temperature the panel is installed in a 1.5m x 1.5m room.

Then to assess further.

 

[Engineer54]

In such a small room, and the temp, being a constant 60 deg, it won't be too long before those panel fans heat up the the rooms ambient, close to the panel temp, configuratively speaking of course, ....unless this small room has a good forced air flow of it's own. ....lol!!!

 

[Knobhead]

It may be worth cooling the room first and see what effect that has on the panel temperature. I personally don’t like panel fans due to dust being drawn in (you can fit filters but these have to be cleaned/changed regularly). But if needs must. The 60° temp is more likely due to the contactors and relays than a few short runs of singles.