RCBO energy consumption

[John-SJW]

RCBOs consume between 1.5 and 2.5 watts for each pole - according to Wylex. Have a CU with largish bank of DP RCBOs then the annual cost of just having RCBOs is substantial. It is not just a few quid a year in electricity costs to have them. My question is:

Do RCBOs still consume electricity when switched off?

 

[davesparks]

What is your source for this power consumption data?

 

[John-SJW]

Wylex specs says full load losses are 1.5 to 2.6 watts per pole. DP is twice the load of SP. You must have noticed RCBOs are warm all the time, even when there is no load running through them. This also makes the insides of a metal CU case warmer. I assume the 1.5 watts is no load energy consumption,

 

[Eddy Currents]

I was intrigued and a quick search found an existing discussion on this
rcbo-energy-consumption-losses

 

[pc1966]

Mostly that is the thermal trip and/or contact resistance so depends I^2 I suspect and so a tiny fraction of the load causing it.

Don't have a spare to measure the actual off-load draw.

 

[pc1966]

Just fondled the front of my own RCBO board (also Wylex) and they are barely warmer to the touch than the main switch of SPD.

 

[John-SJW]

Mine are Wylex a being warm to the touch. Not hot, just warm. Warmer than the surrounding ambient. You need to take the front panel off to touch them. That they consume energy is not in dispute. They do. It is whether they still comnsume energy when they are switched off it what I want to know.

 

[pc1966]

Mine are Wylex a being warm to the touch. Not hot, just warm. Warmer than the surrounding ambient. You need to take the front panel off to touch them. That they consume energy is not in dispute. They do. It is whether they still comnsume energy when they are switched off it what I want to know.

Not while trying to watch the TV!

 

[nicebutdim]

Maybe they do give rise to small losses, but I think 'substantial' would be rather overstating the annual cost involved, regardless of how many ways a board might contain.

 

[John-SJW]

On a wider note, MODEMs, TVs, Sound Bars, neon lights, Oven LED clocks, etc, combined with DP RCBO losses are substantial over a year.

With say 15 DP RCBOs averaging 4W over a year, that is the equiv of having 15 LED 4W lamps on 24/7/365.
As I said: do they consume zero when manually switched off?

 

[UNG]

RCBOs consume between 1.5 and 2.5 watts for each pole - according to Wylex. Have a CU with largish bank of DP RCBOs then the annual cost of just having RCBOs is substantial. It is not just a few quid a year in electricity costs to have them. My question is:

Do RCBOs still consume electricity when switched off?

Over what period of time? per hour it adds up quite significantly over a year but if it is per year it is relatively nothing in terms of overall electric use

 

[John-SJW]

I was intrigued and a quick search found an existing discussion on this rcbo-energy-consumption-losses

What was the conclusion?

 

[nicebutdim]

On a wider note, MODEMs, TVs, Sound Bars, neon lights, Oven LED clocks, etc, combined with DP RCBO losses are substantial over a year.

With say 15 DP RCBOs averaging 4W over a year, that is the equiv of having 15 LED 4W lamps on 24/7/365.
As I said: do they consume zero when manually switched off?

I'm in the habit of switching everything off that isn't being used, but can't imagine switching off breakers for this reason.

Your question is quite reasonable, but I can't imagine that an empirical answer would be likely to change my behaviour.

 

[John-SJW]

Your question is quite reasonable, but I can't imagine that an empirical answer would be likely to change my behaviour.

I want to know how they work.
Going further, for e,g., if someone is going on a month or twos hols, turning off the not used RCBOs, leaving only the alarm and fridge circuits, may make a difference.

 

[nicebutdim]

I'm also curious how any losses might compare to other, older means of circuit protection.

 

[John-SJW]

I was intrigued and a quick search found an existing discussion on this
rcbo-energy-consumption-losses

Thx. Found that via Google. So far it does not answer my Q. Interesting though.

 

[John-SJW]

I'm also curious how any losses might compare to other, older means of circuit protection.

I have the impression a split RCD CU would consume less.

 

[Eddy Currents]

What was the conclusion?

Im not sure why the link wasnt posted so here it is again

https://engx.------.org/f/wiring-and-regulations/23241/rcbo-energy-consumption-losses

 

[nicebutdim]

I have the impression a split RCD CU would consume less.

It may do, but any savings could be wiped out several times over thorough nuance tripping taking out a fridge or freezer.

 

[John-SJW]

It may do, but any savings could be wiped out several times over thorough nuance tripping taking out a fridge or freezer.

Of course that has to be taken into account.

 

[nicebutdim]

Of cure that has to be taken into account.

As does the requirement that we seek to avoid nuisance tripping. I don't think that any losses from RCBOs would be sufficient reason for increasing the likelihood of this.

 

[Aaron b]

I'm also curious how any losses might compare to other, older means of circuit protection.

This is the important question really isn't it. The losses are based on running at the rated current so it's not ever likely to be anywhere near.

The two screenshots are the datasheets of mcbs and rcbos.

 

[nicebutdim]

This is the important question really isn't it. The losses are based on running at the rated current so it's not ever likely to be anywhere near.

What manufacturer are these figures from? Some quite significant losses quoted for certain of those RCBO's

 

[Aaron b]

What manufacturer are these figures from? Some quite significant losses quoted for certain of those RCBO's

They are Hager, I just googled it and picked the first thing that came up.

 

[brianmoooore]

What's the 'consumption' of a rewireable fuse? They must be resistive to work, and the 'consumption' must be enough to melt copper when the current through it is high enough.

 

[mainline]

How about usb sockets, appliances on standby etc etc.

There's going to be losses live with it or turn it off

 

[John-SJW]

What manufacturer are these figures from? Some quite significant losses quoted for certain of those RCBO's

The most on the RCBOs, was 9.3 watts. The 20A model. Quite significant.

 

[nicebutdim]

What's the 'consumption' of a rewireable fuse? They must be resistive to work, and the 'consumption' must be enough to melt copper when the current through it is high enough.

That was my reasoning behind post #15.

 

[nicebutdim]

The most on the RCBOs, was 9.3 watts. The 20A model. Quite significant.

Figures were quoted for several types of RCBO in that data sheet.

I'm overseas at present, with poor internet access, but it would be worth checking which are most likely to be fitted in domestic premises.

 

[mainline]

That was my reasoning behind post #15.

To lessen the concern of loss, maybe cable makers should look into using silver instead of copper ?

Wonder what a 50mtr drum of 4 mm t&e would be and how long it would take to pay for itself.

 

[John-SJW]

Did search on Youtube. John Ward stripped down a Hager 20A RCBO. A quick skim thru the vid, not looking at it all - It looks like they do not consume any energy when the switch is off, answering my original question. Needs more looking.

My oven Wylex 16A RCBO was warm with no current draw. I just turned the RCBO off. I will check tomorrow morning again.

 

[brianmoooore]

Silver instead of copper is a bit extreme, but I've posted on here before about using cables for things like cookers, showers, water heaters, etc., a little larger than those required by VD calculations to reduce losses.

 

[brianmoooore]

Is there a significant difference between the consumption of a RCBO and the equivalent MCB, without the RCD part. Both rely on a bimetal strip, which needs heat (= consumption) to work?

 

[John-SJW]

Is there a significant difference between the consumption of a RCBO and the equivalent MCB, without the RCD part. Both rely on a bimetal strip, which needs heat (= consumption) to work?

Aron B posted the data sheets for Hager mcb & RCBOs.

 

[John-SJW]

What's the 'consumption' of a rewireable fuse? They must be resistive to work, and the 'consumption' must be enough to melt copper when the current through it is high enough.

I have never felt a fuse being warm with no current being drawn.

 

[brianmoooore]

I have never felt a fuse being warm with no current being drawn.

Same for a MCB.

 

[John-SJW]

Same for a MCB.

An MCB will not give off heat if current is not drawn thru it. The heat is via the coil inside which all the current runs thru - fault detection coil. Too much current running thru the coil it detects a fault, so the coil becomes a solenoid throwing a pin inside the coil pushing the spring mechanism disconnecting the supply. Over-current is detected via a bi-metal strip. So the bi-metal strip will get hot consuming energy. There is no neutral in an mcb.

RCBO's have a board inside, which is energised permanently having a neutral to the unit, giving off heat even if no current is being drawn thru the unit, as long as the switch is on.

 

[Aaron b]

To lessen the concern of loss, maybe cable makers should look into using silver instead of copper ?

Wonder what a 50mtr drum of 4 mm t&e would be and how long it would take to pay for itself.

Check out the prysmian cable app. It makes recommendations for energy saving. All ocpd have a thermal part so will need to dissipate heat as part of there function.

The original post makes it sound like there's unnecessary electronics. But to answer the question no it doesn't use energy when switched off as the figures are at the rated current of the device.

 

[John-SJW]

The original post makes it sound like there's unnecessary electronics. But to answer the question no it doesn't use energy when switched off as he figures are at the rated current of the device.

Unnecessary? Mmm, no. Some board designs can use more energy than others.
John Wards vid, I posted, shows that an RCBO, well the Hager he looked at, do not consume any energy when off.

 

[pc1966]

To lessen the concern of loss, maybe cable makers should look into using silver instead of copper ?

Wonder what a 50mtr drum of 4 mm t&e would be and how long it would take to pay for itself.

More like how long until stolen?

Recent metal prices are:

• Silver approx $600 / kg
• Copper approx $7.5 / kg
• Aluminium approx $1.8 / kg

If you then look up the resistivity we have:

• Silver 15.87 nOhm.m = 0.945 * Cu
• Copper 16.78
• Aluminium 26.5 = 1.58 * Cu

So you can see silver has about 5.5% percent better conductivity but about 8000% of the cost, while aluminium needs to be 58% thicker to match Cu but is only about 24% of the cost. However, Al is a right pain to use due to galvanic corrosion risks and is prone to fatigue if flexed, so really only worth it for big DNO like cables and carefully planned joints.

However, the lifetime loss cost of cables ought to be considered at the design stage in addition to the usual 5% volt drop limit, etc. For light loads such as LED circuits then they are very unlikely to reach 3% even these days, but for bigger loads maybe worth it.

 

[pc1966]

Just to add, where you do see silver used for better conductivity is in RF parts where they are plated as at high frequencies the current only flows in the very surface of the conductor (typically tens of microns or less due to the skin effect) so Ag plating is as good as solid.

 

[brianmoooore]

Taking the thread totally off topic, l live in the village where the proposed undersea cable from PV in Morocco is due to connect to the grid.
Anyone care to estimate the losses on that cable?

 

[pirate]

When I read up on this project and saw they were building a cable manufacturing facility at Hunterston which is only an hour away from me, I turned up to sign on for a job, clutching my brand new klein automatic cable strippers...
I didn't get the job...

 

[snowhead]

I turned up to sign on for a job, clutching my brand new klein automatic cable strippers...
I didn't get the job...

If you'd gone with Scuba gear they may have been interested.

4 x 3800km, that's a couple of days work to manufacture...

 

[John-SJW]

I switched off overnight the RCBO supplying a radial which only has washing machine on it - washing machine was unplugged. The RCBO was warm before it switched off. This morning is was cold. I switched it back on at 8 a.m. it is now warm.

A CU with say 15 RCBOs can generate a fair bit of heat inside. So, the likes of a Fuse Box CU, which has lots of space inside is the way to go. Metal cases will help dissipate heat of course.

 

[marcuswareham]

Wylex specs says full load losses are 1.5 to 2.6 watts per pole. DP is twice the load of SP. You must have noticed RCBOs are warm all the time, even when there is no load running through them. This also makes the insides of a metal CU case warmer. I assume the 1.5 watts is no load energy consumption,

I have not noticed RCBOs are warm all of the time, and i am often using large distribution units with over 100 rcbos in and for some shows half of then wont be used, i would say those are at room temp

 

[Julie.]

When I read up on this project and saw they were building a cable manufacturing facility at Hunterston which is only an hour away from me, I turned up to sign on for a job, clutching my brand new klein automatic cable strippers...
I didn't get the job...

Pity, you could take a quick swim over to Millport, and get 1960's/70's style food in the Ritz.

Since around the early '80's I have been going to both the Scottish national sailing centre and general diving off Cumbrae, and it's like a pilgrimage to go to the Ritz and re-live my childhood memories in a cafe that remains exactly the same since the 50's... early 70's

 

[pirate]

Been to Milport many, many times in my younger years when I sailed most weekends on the Clyde from my mooring in the Kyles of Bute. I've never been in the Ritz, as far as i can recall, so will make that "pilgrimage" next time and report back! Sold my boat some years back, but I have a SIB and just had my outboard motor fully seviced, so will be making some trips soon, hopefully.

 

[John-SJW]

I have not noticed RCBOs are warm all of the time, and i am often using large distribution units with over 100 rcbos in and for some shows half of then wont be used, i would say those are at room temp

Believe me, they do get warm. On the top and to the side. I have quality Wylex RCBOs, not some cheap Ebay trash, and they do get warm. MCBs will become warm if highish current is running thru them - e.g., 4A running thru a 6A mcb for a while will make it warm. Which brings me to the point of using the highest mcb rating you can to reduce the bi-metal strip bending consuming energy and getting warm.

 

[littlespark]

Which brings me to the point of using the highest mcb rating you can to reduce the bi-metal strip bending consuming energy and getting warm.

You should size your mcb to the correct one to protect the circuit, or am I missing your point?


Let’s say a standard new board with maybe 10 rcbo’s (not thinking AFDD yet) Nothing extreme load like a weed farm, but normal…. How much heat generated? How much power consumption? And would say a half module blank between each one would help?