Assorted Christmas / Halloween Light questions

[JB-BJ]

I do have one 10 mA RCD socket, so using that one would hope the socket would trip before the CU, however 10 mA RCD's are expensive, and with all RCBO's loosing one would only be a problem if from front of house ring final which also powers the freezers. If I use rear of house ring final or flat ring final it would not really matter.

However last house there were four circuits on each RCD, so I had to be very careful using outside lights as loosing a freezer full of food at Christmas can be a tad expensive.

Yes, the RCD tripping would knock out all the sockets (including the freezer), but it's my understanding that a modern freezer left unopened would stay happily stay at a food-safe temperature for at least 24 hours if unpowered, so probably not an issue unless going away for a couple of days.

 

[ericmark]

Yes, the RCD tripping would knock out all the sockets (including the freezer), but it's my understanding that a modern freezer left unopened would stay happily stay at a food-safe temperature for at least 24 hours if unpowered, so probably not an issue unless going away for a couple of days.

It is all down to when in the cycle it fails, and how much food is in it, and how big it is. So a frost free freezer turns off every so often and a heating element turns on and melts all the ice that has built up behind the shield between the evaporator and freezer compartment and the water runs onto a tray over the motor so once cycle if finished the water will evaporate due to heat of motor, since the fan is not running during the defrost cycle the heat is not transferred to the food, once the defrost cycle finishes the fan runs again so cold air is circulated around the freezer. So at the point when the heater switches off the freezer would likely only remain frozen for a couple of hours, and if empty less than that.

But if it failed just before the defrost cycle starts then likely it will remain frozen for 8 hours if the freezer is full.

-18°C is the freezing point of brine, and also the temperature of most freezers, food tends to have a star rating, and if higher than -18°C the time if can be kept is reduced, the problem is we don't know once the freezer has gone above -18°C how long the food can be kept.

I was in the kitchen when my freezer failed, I heard the noise, so I had a freezer in the garage used for beer brewing, so turned that on, and allowed it to cool for an hour before transferring the food. I found most the food frozen stiff, but the food at the top even in one hour had started to defrost so had to be eaten.

Chest freezers don't have a defrost cycle, and yes they will keep food frozen for around 24 hours, but not upright freezers, mine show the highest temperature reached when switched back on, so I do know if food is safe, as long as no one has opened the door, which cancels the highest temperature display, but if you know power has failed clearly you don't want to open door, so a bit of guess work unless there is a display to know if food is OK.

I lost two freezers full of food while living with mother due to the RCD tripping, we only visited our house to check all OK every few days, so were unable to reset the RCD in time, hard to put a price on food lost, but well over the difference between a RCD and multi-MCB's and having all RCBO's, so when we moved I changed fuse box for consumer unit with all RCBO's. It was easy when going from no RCD protection to full RCD protection, but in the last house the cost to change the two fuse boxes each on its own RCD for a consumer unit with all RCBO's resulted in it not being done. And as far as I am aware my son who now lives in the house has not yet fitted a new consumer unit. We are both electricians so cost to upgrade is not that much, more down to time than cost.

I like Christmas and all the lights, but will only switch on when at home, as just far too easy for water to cause a RCD to trip, unless the circuit has no items which will cause problems should the RCD/RCBO trip.