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?

 

[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?

 

[John-SJW]

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?

A 1.00mm LED lighting circuit can use a 3A MCB, as the current draw will not get near to 3A. My LED lighting circuit draws 1.3 A max - I used an amp clamp with all lights on. Using a 6A mcb would reduce the possibility of a warmish MCB/RCBO and still protect the cable, one of its two prime functions. I always try to fit MCB/RCBO/fuses as low a value as possible, to give added protection in fault conditions on connected appliances.

The specs for MCB and RCBO energy consumption were posted by Aron B. Good idea, I did think of spacing out RCBOs to dissipate heat, if there is enough space in the CU. Unfortunately I have no surplus ways.

 

[Aaron b]

The specs for MCB and RCBO energy consumption were posted by Aron B. Good idea, I did think of spacing out RCBOs to dissipate heat, if there is enough space in the CU. Unfortunately I have no surplus ways.

It would just be the mcb dissipating the heat better. The heat will still be produced. You might be thankful for a bit of heat next month...

 

[John-SJW]

I heard about people using bitcoin mining rigs as a source of heating. I'm not sure about now

It would just be the mcb dissipating the heat better. The heat will still be produced. You might be thankful for a bit of heat next month...

Heat I have purchased . But heat when I do not need heat.

 

[ipf]

Blimey! Reading this thread is worrying.
With the current economic problems, it'll cost more for a week's increase in grocery prices than a year of this craP.

 

[mainline]

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?

I've no doubt that blanks may help to dissipate some heat, but I don't think I will be fitting a CU with twice the ways just to get some space between them, I shall stick to what I've been doing for years with no problems.

And as for sizing, I shall stick to Regulation 433.1.1

 

[mainline]

Heat I have purchased . But heat when I do not need heat.

If it's a concern, oversize all the cables.

Edit: oh I forgot you won't do that, as in another thread you argue for smaller ones.

 

[John-SJW]

If it's a concern, oversize all the cables.

Edit: oh I forgot you won't do that, as in another thread you argue for smaller ones.

Oversize cables? Another one who does not get it.

 

[Avo Mk8]

Do RCBOs still consume electricity when switched off?

I suspect I may regret this, but I will attemt to answer your original question..

From a scan of published block schematics of RCBO's, and John Wards teardown of a compact Hager (below), power for the electronics appears to come from 'switched live' - ie is disconnected when breaker 'off'.
My conclusion is that the answer to your question is "no".

I want to know how they work.

Might help if you have 21 minutes to spare! (the viewers comments are also useful)

 

[John-SJW]

I suspect I may regret this, but I will attemt to answer your original question..

From a scan of published block schematics of RCBO's, and John Wards teardown of a compact Hager (below), power for the electronics appears to come from 'switched live' - ie is disconnected when breaker 'off'.
My conclusion is that the answer to your question is "no".

I want to know how they work.

Might help if you have the time!

I did conclude that. I also did post the same John Ward vid.

Great vid by John Ward. Big Clive tears a Hager down that had fried. Worth looking at.

 

[Avo Mk8]

I did conclude that. I also did post the same John Ward vid.

Great vid by John Ward. Big Clive tears a Hager down that had fried. Worth looking at.

Sorry missed that