Freezer-Extension Lead Exclusion-Guarantee.

I've seen warnings like that on a lot of IT equipment - especially stuff of US origin.


I don't know for certain the manufacturer's thinking but suspect that from a global perspective that extension leads often have less reliable earthing than fixed wall sockets (remember that most of the rest of the world has an option of plugs without an earth connection - usually with no physical constraint to stop 3-pin plugs being inserted into 2-pin trailing sockets; then there's the additional voltage drop and increased Zs (especially if the extension lead is thin and/or long) and generally the lower quality of extension leads (less reliable contacts etc.). If they were determined they could have specified a list of conditions under which an extension lead would be acceptable (c.s.a., length, presence of earth connections and so on) which your typical customer would probably think gobbledygook, or just make it simple (for themselves) and say don't.


I agree though that a typical UK extension lead of modest length, reasonble c.s.a. and decentt quality is unlikely to cause any problems.


   - Andy.

There is also a problem of supply impedance - an extension lead may be
50m long in H05VV-F 1.25mm²  That may give compressor starting problems.

The average load for is fridge is low, but the inrush us not (this page suggests 14:1 average to starting surge for a fridge ).

This is very real ... and can affect other single-phase induction motor appliances like tumble dryers as well.


Basically, if there's too much impedance in the supply, the voltage on the capacitor in series with the start winding (capacitor-run motor type) becomes too large, and the motor also overheats due to increased "slip". This eventually damages the capacitor and/or the motor.


Can also occur with detached garage extended from ring-main in T&E from a plug or spur in a ring in the house (fuses also increase supply resistance). Also seen this in cases where there have been problems with crimping or braising of contacts in moulded plugs on the appliance themselves.

Agree that a good quality extension lead of generous CSA and modest length should be fine. However a long or thin lead could indeed be problematic for the reasons already given of starting current.

For similar reasons, operation of freezers from small generators or inverters can be problematic. My freezer is connected to the UPS, but it is a 2,500 VA UPS for a load of a few hundred watts.

A few years back, in another life, I overheard a conversation with the technical support people of a certain major UK lottery provider whose name is not dis-similar to King Arthurs' castle.


The problem was that the lottery terminal in the village shop would not connect to lottery HQ and hence couldn't be used to sell tickets.


The help line people were blaming the fact that the terminal was connected via an extension lead & not directly into a wall socket.... apparently the extension lead "prevented the terminal charging up properly and so it cant talk"

I wonder how many freezers in garages are powered via an extension lead from the house. ?

Now my customer has a lovely new dedicated 13 Amp single socket located right next to the tall freezer. Joy and Bliss!


Z.

"I overheard a conversation with the technical support people of a certain major UK lottery provider whose name is not dis-similar to King Arthurs' castle"


Good idea of yours not to name them Andy - No name no kitbag sort of thingy.

The story about the lotto terminals made me laugh out loud you couldn't make it up could you! I read the information about appliance inrush currents it's not something that normally gets much thought one thing in that article a bit later on was that he said that microwave ovens use half wave rectification is this still true? I ask because I thought half wave rectifiers were now banned in all loads except those of less than 100 watts or so apparently back in he good old days when TVs used half wave it caused problems with transformers overheating so that's why it was banned