RCBOs and lighting?

pauldavis123

I am getting a commercial unit wired and was wondering if I could ask the electrician if it was possible to wire in all the lamps off the 2.5mm sockets as the entire board is RCBOs.

Each room has its own circuit.

Only one lamp in one room should go if the is a fault.

All lamps are LED bulkheads.

Help with maintenance, energy usage metering and reconfigurability.

2011

Very bad practice, I would be surprised if the electrician agrees to this.
Why would you want this?

tomplate

I presume he wants to monitor the energy on a single circuit

It's better to keep the lighting separate

pauldavis123

2011 wrote: »

Very bad practice, I would be surprised if the electrician agrees to this.
Why would you want this?

From what I have read the lighting is kept on (several) seperate circuts to allow only certain areas to fail and leave lighting still available in the building for escape / faultfinding.

If each lamp is on one RCBO is this not a better solution? Only one room will go dark.

Apoligies if missing something basic

My reasons are maintenance, energy usage metering and reconfigurability.

ted1

pauldavis123 wrote: »

From what I have read the lighting is kept on (several) seperate circuts to allow only certain areas to fail and leave lighting still available in the building for escape / faultfinding.

If each lamp is on one RCBO is this not a better solution? Only one room will go dark.

Apoligies if missing something basic

My reasons are maintenance, energy usage metering and reconfigurability.

Emergency lighting will work of batteries.
What type lamps are being fitted , I can’t see much benefit measuring individual lighting loads

tomplate

It's not the normal practice

Will a fault plunge a room into darkness creating a hazard for workers in the room?

2011

pauldavis123 wrote: »

From what I have read the lighting is kept on (several) seperate circuts to allow only certain areas to fail and leave lighting still available in the building for escape / faultfinding.

Correct.

If each lamp is on one RCBO is this not a better solution? Only one room will go dark.

For a start RCDs / RCBOs can suffer from nuisance tripping. Not something desirable on a lighting circuit.

Also a faulty appliance is far more likely to cause a loss of lighting.

Remember loss of lighting can make an accident more likely. This is an important consideration in this claims culture we live in. Your insurance company may also use this unapproved deviation from the norm to avoid paying out in the event of a claim.

As this is a commercial premesis you should also consider emergency lighting.


Deviation from electrical norms without good reason is not recommended.

My reasons are maintenance

How would this help? If your electrician can’t understand a lighting circuit the he/she is incompetent.

energy usage metering

This can still be metered.

reconfigurability.

pauldavis123

ted1 wrote: »

I can’t see much benefit measuring individual lighting loads

While super small it is easier to any prospective tennant that all the usage is on one metered circut. I know this can still be done , just 6 more MCB or RCBOs.

tomplate

If the unit is being subdivided what you'd do is fit a sub-board at each room with separate circuits for lighting and power and provide isolation for the unit.

Energy monitoring can be done on the distribution circuit at the main board or the sub board

What you're describing is a bodge kind of job

pauldavis123

tomplate wrote: »

It's not the normal practice

Will a fault plunge a room into darkness creating a hazard for workers in the room?

True

pauldavis123

2011 wrote: »

Correct.



For a start RCDs / RCBOs can suffer from nuisance tripping. Not something desirable on a lighting circuit.

Also a faulty appliance is far more likely to cause a loss of lighting.

Remember loss of lighting can make an accident more likely. This is an important consideration in this claims culture we live in. Your insurance company may also use this unapproved deviation from the norm to avoid paying out in the event of a claim.

As this is a commercial premesis you should also consider emergency lighting.


Deviation from electrical norms without good reason is not recommended.



How would this help? If your electrician can’t understand a lighting circuit the he/she is incompetent.



This can still be metered.

OK, I'll go with the norm, thanks for all the info

pauldavis123

tomplate wrote: »

If the unit is being subdivided what you'd do is fit a sub-board at each room with separate circuits for lighting and power and provide isolation for the unit.

Energy monitoring can be done on the distribution circuit at the main board or the sub board

What you're describing is a bodge kind of job

Probably the best way to go about it thanks :rolleyes:

2011

tomplate wrote: »

If the unit is being subdivided what you'd do is fit a sub-board at each room with separate circuits for lighting and power and provide isolation for the unit.

Energy monitoring can be done on the distribution circuit at the main board or the sub board

What you're describing is a bodge kind of job

Exactly.
Depending on a number of factors it may be possible to use the socket circuit supply cable to supply the sub board in each case. I would be reluctant to have just one light per room.

What sort of commercial premesis is it?

pauldavis123

2011 wrote: »

Exactly.
Depending on a number of factors it may be possible to use the socket circuit supply cable to supply the sub board in each case. I would be reluctant to have just one light per room.

What sort of commercial premesis is it?

1. Room is only 3m x 3m,
2. Workspaces.

I'll go with the sub board.

Risteard81

2011 wrote: »

For a start RCDs / RCBOs can suffer from nuisance tripping. Not something desirable on a lighting circuit.

I'd have to disagree that RCD protection is undesirable on a lighting circuit generally as tripping is indicative of an earth fault. Particularly with a neutral/Earth fault on a lighting circuit this could be useful for safety reasons.

That said the generally accepted practice here is to segregate lighting and small power circuits and I wouldn't advocate not doing that without very good reason. But I don't see an issue with lighting circuits having an RCBO. (In fact, for bathroom lighting circuits it's a rule.)

tomplate

Risteard81 wrote: »

I'd have to disagree that RCD protection is undesirable on a lighting circuit generally as tripping is indicative of an earth fault. Particularly with a neutral/Earth fault on a lighting circuit this could be useful for safety reasons.

That said the generally accepted practice here is to segregate lighting and small power circuits and I wouldn't advocate not doing that without very good reason. But I don't see an issue with lighting circuits having an RCBO. (In fact, for bathroom lighting circuits it's a rule.)

Can't see any advantage in general having lights on RCDs

Bruthal

tomplate wrote: »

Can't see any advantage in general having lights on RCDs

Even this bathroom thing. Just because its a rule doesnt mean its better having them on an RCD.

I would say there is more risk of falling in a dark bathroom than being electrocuted by a ceiling light.

Risteard81

tomplate wrote: »

Can't see any advantage in general having lights on RCDs

Again, consider neutral/Earth faults coupled with loss of connection of the neutral tail to the PEN conductor and the consequences of this. I've seen it and it's not pretty. As I pointed out operation of the RCD (RCCB/RCBO) will almost certainly be due to an earth fault.

Bruthal

Risteard81 wrote: »

Again, consider neutral/Earth faults coupled with loss of connection of the neutral tail to the PEN conductor and the consequences of this. I've seen it and it's not pretty. As I pointed out operation of the RCD (RCCB/RCBO) will almost certainly be due to an earth fault.

What was the nature of that fault?

Risteard81

Bruthal wrote: »

What was the nature of that fault?

There was a neutral/Earth fault on an outside light. A homeowner had a non-REC in to rewire downlights because the cable had melted to them. After they were rewired the cables were burned again and the non-REC didn't want to know. At this point I was called and discovered that the entire installation load was returning through the neutral/Earth fault in the 1.5mm^2 T&E as the neutral tail had no continuity between the ESB meter and the DB. (Now I do all of his electrical work.)

I'm not trying to push RCDs for lighting but just pointing out why they may not be a bad thing. In fact the 18th Edition of the IET/IEE Wiring Regulations in the north and Britain (which comes into effect on 1st January) will require any circuit supplying luminaires in a domestic dwelling to be RCD protected.

Who knows what will happen with the 5th Edition of the Wiring Rules?

2011

Risteard81 wrote: »

I'd have to disagree that RCD protection is undesirable on a lighting circuit generally

You are entitled to your opinion. It is my view that this would result in a net increase of risk for the reasons given.

as tripping is indicative of an earth fault. Particularly with a neutral/Earth fault on a lighting circuit this could be useful for safety reasons.

Would you apply this logic to all fixed appliances? The cooker too?

That said the generally accepted practice here is to segregate lighting and small power circuits and I wouldn't advocate not doing that without very good reason.

That is exactly what I said.

But I don't see an issue with lighting circuits having an RCBO. (In fact, for bathroom lighting circuits it's a rule.)

I think the this rule is a bad idea.

I'm open to correction here but I don't believe that this is a requirement if the lighting in the bathroom is ELV. If that is the case I would deal with it that way.

2011

Risteard81 wrote: »

There was a neutral/Earth fault on an outside light. A homeowner had a non-REC in to rewire downlights because the cable had melted to them.

So you are saying that despite the lights being rewired the neutral to earth fault was not fixed?

After they were rewired the cables were burned again and the non-REC didn't want to know.

.......because the entire neutral current for the house was passing through the neutral of the outside light, through the short, back along the earth wire to the main earth bar, to the (10 mm sq.?) earth rod neutralising link [Edit].

If that was the case the volt drop must have been colossal when larger loads were switched on as the impedance of the return path could be so high.

At this point I was called and discovered that the entire installation load was returning through the neutral/Earth fault in the 1.5mm^2 T&E as the neutral tail had no continuity between the ESB meter and the DB. (Now I do all of his electrical work.)

So what did the customer say his electrical issues were? I would imagine that he had a lot of under voltage issues that became very noticeable when things like the hob were switched on.

What caused the issue? Did the REC just not connect the tails properly at the meter? I saw this before.

In fact the 18th Edition of the IET/IEE Wiring Regulations in the north and Britain (which comes into effect on 1st January) will require any circuit supplying luminaires in a domestic dwelling to be RCD protected.

Yeah, different country and they will be even further removed post Brexit.

Who knows what will happen with the 5th Edition of the Wiring Rules?

I will ask and see what I can find out.
I doubt it to be honest.

Risteard81

2011 wrote: »

Would you apply this logic to all fixed appliances? The cooker too?

I'm certainly not opposed to it.

In a new domestic installation in the north typically every circuit would be RCD protected. The reality is that this doesn't generally lead to any issues (even with cookers).

For a southern installation I don't make a habit of putting RCD protection where it's not required, but just wanted to point out that there can be benefits to such an approach.

tomplate

Bruthal wrote: »

Even this bathroom thing. Just because its a rule doesnt mean its better having them on an RCD.

I would say there is more risk of falling in a dark bathroom than being electrocuted by a ceiling light.

in time the rules will surely be EFL protection on all domestic circuits


they just need to get it right and not create additional hazards with the rule changes

Risteard81

2011 wrote: »

So you are saying that despite the lights being rewired the neutral to earth fault was not fixed?

.......because the entire neutral current for the house was passing through the neutral of the outside light, through the short, back along the earth wire to the main earth bar, to the (10 mm sq.?) earth rod neutralising link [Edit].

The fault wasn't fixed presumably because no testing was done and the non-REC was unaware of it.

The entire load current was not returning through the Earth electrode but through the main protective conductor (neutralising link) to the PEN conductor. (Obviously as a parallel path some would flow through the electrode but this would be a tiny proportion.)

There were volt drop issues such as dimming with the electric shower running but still none of them clicked what was going on.

tomplate

Bruthal wrote: »

Even this bathroom thing. Just because its a rule doesnt mean its better having them on an RCD.

I would say there is more risk of falling in a dark bathroom than being electrocuted by a ceiling light.

you could be having a bath though and the light falls off the ceiling


you decide to tidy up the wires while having your bath and get electrocuted

Bruthal

tomplate wrote: »

you could be having a bath though and the light falls off the ceiling


you decide to tidy up the wires while having your bath and get electrocuted

I always wondered is it possible to survive being electrocuted

2011

Risteard81 wrote: »

The fault wasn't fixed presumably because no testing was done and the non-REC was unaware of it.

I can’t help but notice the persistent use of the term “non-REC”. Is this strange beast an electrician or not? Surly that is more relevant?

There is no “REC qualification”. Besides the overwhelming majority of electricians work for RECs so they are entitled to do unsupervised electrical work.

tomplate

Bruthal wrote: »

I always wondered is it possible to survive being electrocuted

it is



you have to be electrocuted to death to die

Risteard81

tomplate wrote: »

it is



you have to be electrocuted to death to die

Technically electrocution means that it is a fatal electric shock. It was originally a contraction of "electrical execution" when the electric chair was invented.

Risteard81

2011 wrote: »

I can’t help but notice the persistent use of the term “non-REC”. Is this strange beast an electrician or not? Surly that is more relevant?

I used the term because that was how the person was described to me. He thought that he was a registered contractor but later found out that he wasn't. As I don't know who that person was I can't offer an opinion as to whether he was an Electrician or not.

Non-REC was not being used in a derogatory sense - simply the only factual way to describe the person unknown.