quick questions

M cebee

anyone know what the rules are regarding

-2 different circuits in a back box

-2 different circuiits in a single multicore


i've always assumed it's either not allowed or bad practise

-is there specific rules covering this


thanks

Bruthal

I would think the 2 circuits is allowed in the one box, there would be 2 lighting circuits in some switch boxes, landing light switch upstairs would have the upstairs and downstairs lighting circuits in it.

The multicore im not sure, im sure its done anyway though. Would probably want to be a swa to do it.

2011

I would think the 2 circuits is allowed in the one box, there would be 2 lighting circuits in some switch boxes, landing light switch upstairs would have the upstairs and downstairs lighting circuits in it.

+ 1

The multicore im not sure, im sure its done anyway though.

Not sure either. I don't think it would be good practice. I cant think of ever seeing it done. I can think why it may be unsafe though as you may think you have isolated the cable, but in fact you have only party isolated it. IMHO with mains voltage it is best to have no surprises when you are designing something.

Why would you want to do it???

Bruthal

I seen the multi-core done on a conveyor system before now that i think of it, about 10 years ago, groups of 3 or 4 small motors a bit away from the controller panel in various places on the conveyors, so 1.5 multi core swa`s were run to JB`s close to the motors. At least in this sort of situation the main isolator can be locked off and thats everything de-energised.

M cebee

2011 wrote: »

+ 1


Not sure either. I don't think it would be good practice. I cant think of ever seeing it done. I can think why it may be unsafe though as you may think you have isolated the cable, but in fact you have only party isolated it. IMHO with mains voltage it is best to have no surprises when you are designing something.

Why would you want to do it???

don't neccessairly want to do

just want to know if there's rules on it

i don't normally combine the up/down lighting circuits in a box

M cebee

robbie7730 wrote: »

I seen the multi-core done on a conveyor system before now that i think of it, about 10 years ago, groups of 3 or 4 small motors a bit away from the controller panel in various places on the conveyors, so 1.5 multi core swa`s were run to JB`s close to the motors. At least in this sort of situation the main isolator can be locked off and thats everything de-energised.

when i worked industrial the multicore swa's were common

but the isolating switch for machine would knock off the lot obviously

so is there a rule covering this?

2 final circuits on a swa-i'm sure there is

2011

At least in this sort of situation the main isolator can be locked off and thats everything de-energised.

Yes, I would have no issue with this as it is clear how to isolate from a single point.

ntpm

Contols cabling boards and JB usually have multiple live conductors ( cables) that would switch on /off (become "live") depending on external conditions.

As stated earlier there should be one main source for the Live feed for "Safe Issolation" should you have to work on it.
If there are two separate sources of Live feed then a label should be on the front of the booard or JB stating " Multiple Sources of LIVE VOLTAGE" or similar.... i have seen these labels but can't remember exact wording.

It is the reponsiblity of the Competent Person who is working on the electrics to ensure they have sufficient information regarding the electricl wiring layout etc.

2011

Contols cabling boards and JB usually have multiple live conductors ( cables) that would switch on /off (become "live") depending on external conditions.

Yes, control panels can have many signals going to and from them. But in my experience although a multicore may have several mains voltage signals within it they are all fed from the same circuit and therefore the same protective device. This would be normal and I would have no issue with that.

However, I have not seen more than 1 circuit within a single multicore cable at mains voltage. I am not saying it has not been done, I just have not seen it.

What I have often seen is multiple PLC I/O within a multicore cable, these cables are generally refereed to as "multipair cables". Typically PLC I/O are at 24VDC so I don't think they apply to the OPs question.

For example: On a project that I am working on the control voltage in the MCCs is 110VAC. Typically a multicore SWA is wired for the MCC (Motor Control Center) cubicle to one or more local control stations. These would have multiple signals for emergency stop, jog, stop, run lamp and hand/off auto. This would all be fed from a 6A MCB within the MCC cubicle. A multipair cable would then be wired from the same cubicle to a PLC. This cable would contain I/O at 24VDC and each instrument "loop" would have its own fuse (located in the PLC panel). The I/O signals within this cable could be something like run, run feedback, overload trip, thermister trip, reset, manual select.

Bruthal

M cebee wrote: »

i don't normally combine the up/down lighting circuits in a box

But its normally done though, thats what i meant in my post #2,
the landing light may be a 2 gang to also do the bathroom light in a lot of houses, and landing light would be from downstairs circuit.

Often seen in industrial too, even seen different phases into a multi gang switch point. I dont think thats a great idea though, i wonder what the rules are on that these days, should be contactor switching in them situations, but it certainly has been done.

2011

Agree with Robbie

Bruthal

2011 wrote: »

Agree with Robbie

What about the different phase lighting circuits in the one multi gang light switch, it would be metal boxes and switches of course, do you see this much now, or is it allowed now do you think?

ntpm

robbie7730 wrote: »

What about the different phase lighting circuits in the one multi gang light switch, it would be metal boxes and switches of course, do you see this much now, or is it allowed now do you think?

There may be an issue with multi gang light switches (MGLS) in landing upstairs.
example:
Downstairs light supply feed from a mcb1.
Two way loop to upstairs switch in MGLS.
Upstairs MGLS also has supply feed but from a different mcb2.

Proper/ Total Safe issolation would require switching of MCB1 and MCB2 and neutral issolation (if neutrals in the MGLS) (ie. Double pole issolation).
As neutrals are connected in neutral bus bar the safest method of issolation is to switch off main fuse in consumer unit.

A Compotent Person would have knowledge and training to identify best practise for issolation.

Bruthal

ntpm wrote: »

Robbie7730
What about the different phase lighting circuits in the one multi gang light switch, it would be metal boxes and switches of course, do you see this much now, or is it allowed now do you think?

ntpm
There may be an issue with multi gang light switches (MGLS) in landing upstairs.
example:
Downstairs light supply feed from a mcb1.
Two way loop to upstairs switch in MGLS.
Upstairs MGLS also has supply feed but from a different mcb2.

Proper/ Total Safe issolation would require switching of MCB1 and MCB2 and neutral issolation (if neutrals in the MGLS) (ie. Double pole issolation).
As neutrals are connected in neutral bus bar the safest method of issolation is to switch off main fuse in consumer unit.

A Compotent Person would have knowledge and training to identify best practise for issolation.

Yes but its done everywhere i thought. But these are the type of reasons electricians are required for even seemingly simple jobs.

And where you quoted me i was more talkin about industrial installations. Which i have been away from a while now.

2011

I have seen many examples of switches from different circuits and even different phases being contained within the same switch box. I don't see the issue and I am not aware of it being against any regulation.

For example: In many cases open plan offices could have in excess of 100 light fittings all switched directly from a large bank of switches. I remember connecting these up as an apprentice all over the IFSC. I don't really do domestic installations but I think that most also have two lighting circuits sharing a switch box at the top or bottom of the stairs.

ntpm

robbie7730 wrote: »

Yes but its done everywhere i thought. But these are the type of reasons electricians are required for even seemingly simple jobs.

Any where you quoted me i was more talkin about industrial installations. Which i have been away from a while now.

No insults intended.
I was originally trained in commercial installations and automation / controls but I also carry out Domestic Installations.
May be due to the Celtic Tiger and Building Boom many Electricians were Qualified and Trained to current ETCI National Rules but IMO was backed up with work experience on Domestic wiring only.......... yet I find more ambiguity in Domestic Installation.

Bruthal

Yea id does not seem to be a big deal, i do know some fellas did not like wiring different phases into a single switch box though, and just used control circuits to the switch banks.

But in a steel box and steel switch you would`t expect it to be much of a problem.

2011

May be due to the Celtic Tiger and Building Boom many Electricians were Qualified and Trained to current ETCI National Rules but IMO was backed up with work experience on Domestic wiring only.......... yet I find more ambiguity in Domestic Installation.

Yes I know what you mean.

I have also seen electricians with only industrial experience trying to do domestic. They are very different areas. IMHO the qualifications should be more specific as to what type of electrician someone is. There is a world of difference.

Bruthal

ntpm wrote: »

No insults intended.
I was originally trained in commercial installations and automation / controls but I also carry out Domestic Installations.
May be due to the Celtic Tiger and Building Boom many Electricians were Qualified and Trained to current ETCI National Rules but IMO was backed up with work experience on Domestic wiring only.......... yet I find more ambiguity in Domestic Installation.

I did`t see any insults anyway. No i was just saying that i seen plenty of multi circuits over the 3 phases used into lighting switch banks, but in the industrial, not in domestic. In domestic its commen to have the upstairs and downstairs circuits in the one switch usually on the landing, but it could have it with the hall light on the upstairs circuit either, so the hall switch may have the 2 circuits. Its a non issue i believe.

Most of my experience is in the industrial, i prefered it myself.

2011

yet I find more ambiguity in Domestic Installation.

I think that there are more checks carried out on installations in the industrial sector than domestic. In domestic generally the only person to check the work is the electrician that installs it.

In industry it might be designed by an engineer, drawings may then be reviewed by the client, work installed by the electrical contractor, inspected by the the client, contractor and designer/supervisor. There is a greater chance of a mistake being noticed.

Bruthal

2011 wrote: »

Yes I know what you mean.

I have also seen electricians with only industrial experience trying to do domestic. They are very different areas. IMHO the qualifications should be more specific as to what type of electrician someone is. There is a world of difference.

Im not sure if i would quite go that far, there is a fair difference alright,
i think the industrial is more involved myself, but i think it may be easier on a big industrial site in some ways, as you might get away with just putting up trunking and tray for months, on a house you will have to know how to wire circuits, but being qualified itself is still early in the electrical trade. It was the esb i did apprenticeship with, in which there was neither a major experience in domestic or industrial, although it was more domestic because they had house rewiring and storage heaters at that time,
But where would that leave a person, a qualified esb electrician?

They are different areas though, and a fella with 100% industrial experience could struggle in the domestic probably, but i found most decent sparks from the industrial would be competent in domestic.

In every aspect there will be good and bad tradesmen. A good one can adapt, if we say someone is a qualified industrial electrician then he would not be qualified to work on domestic. Yet it should be simple for him to change an MCB board etc, in a house. I still believe the 4 years apprenticeship is just the basis of becoming an electrician, but we are still qualified at the end of the 4 years.

Bruthal

2011 wrote: »

I think that there are more checks carried out on installations in the industrial sector than domestic. In domestic generally the only person to check the work is the electrician that installs it.

In industry it might be designed by an engineer, drawings may then be reviewed by the client, work installed by the electrical contractor, inspected by the the client, contractor and designer/supervisor. There is a greater chance of a mistake being noticed.

Yes and the industrial sparks probably would not have to be as up to scratch on regs as the domestic sparks for the same reasons.

Bruthal

ntpm wrote: »

Robbie7730
Any where you quoted me i was more talkin about industrial installations. Which i have been away from a while now.

ntpm
No insults intended.

Just noticed my typo which probably made you think i thought you were insulting, That should of said And where:)

2011

I am not suggesting that an industrial electrician is better or more highly qualified than a domestic or vise versa. I am just saying that it is such a broad area that this should be recognized in the qualification that each gets at the end of a 4 year apprenticeship.

Bruthal

2011 wrote: »

I am not suggesting that an industrial electrician is better or more highly qualified than a domestic or vise versa. I am just saying that it is such a broad area that this should be recognized in the qualification that each gets at the end of a 4 year apprenticeship.

Yes i know what your saying. But i do believe when your a qualified electrician your qualified based on completing an apprenticeship according to the current criteria for qualifying. It just states that you completed an apprenticeship.

How well you do after that will be decided by your abilities in the chosen sector you work in, rather than by the certificate saying you qualified in domestic or industrial. If a person is great at industrial but not so at domestic, then it would show would`t it. But if a person was great at both but only qualified in industrial, what then.

A lot of electrical work involves work that is not actually strictly electrical, and how good a person is at this can be a major factor in their overall ability. I think they do this in the US, one fella for conduit, another for wiring etc.

Your right, it is a broad area, thats why it involves a 4 year apprenticeship and years of experience after this. And the number of years experience is noted when you work as electrician up to 5 after apprenticeship anyway, or at least its supposed to be.

But i do take your point, maybe it would work better, the above is just a few notes of what i think as well. I do believe the highly experienced industrial electrician would adapt quicker to domestic electrical than the other way round. The industrial has a more broad area of work than the domestic. But im not saying in any way that the industrial electrician is better, the industrial section is so varied that you could almost say it could have various electrician types itself. But the domestic has a lot more to it than meets the eye also, so your not wrong in your view in my opinion.

Bruthal

2011 wrote: »

I am just saying that it is such a broad area that this should be recognized in the qualification that each gets at the end of a 4 year apprenticeship.

Now that you mention it i think my cert does say something about the type of apprenticeship i did. I must look at it later,

M cebee

ntpm wrote: »

There may be an issue with multi gang light switches (MGLS) in landing upstairs.
example:
Downstairs light supply feed from a mcb1.
Two way loop to upstairs switch in MGLS.
Upstairs MGLS also has supply feed but from a different mcb2.

Proper/ Total Safe issolation would require switching of MCB1 and MCB2 and neutral issolation (if neutrals in the MGLS) (ie. Double pole issolation).
As neutrals are connected in neutral bus bar the safest method of issolation is to switch off main fuse in consumer unit.

A Compotent Person would have knowledge and training to identify best practise for issolation.

-isolation of both live circuit conductors not required here for TN systems(rules 462.1,461.2)
(although as you prob know in the UK the 'main isolating switches' are DP for single-phase installations)

-appliance isolators normally isolate all live conductors

cast_iron

2011 wrote: »

I have seen many examples of switches from different circuits and even different phases being contained within the same switch box. I don't see the issue and I am not aware of it being against any regulation.

I'm not sure if it's against any regulation, but it's considered bad practice to leave 400v at a switch when it's not necessary. It can be of a nuisance to get right when 2-way switching is involved with corridor lighting going every which way. Not to mention switches with supplies fed from different distribution boards (upstairs/downstairs setup).

Bruthal

cast_iron wrote: »

I'm not sure if it's against any regulation, but it's considered bad practice to leave 400v at a switch when it's not necessary. It can be of a nuisance to get right when 2-way switching is involved with corridor lighting going every which way. Not to mention switches with supplies fed from different distribution boards (upstairs/downstairs setup).

Well i think anyone sensible would design the installation to avoid feeding the same switch group from different DB`s.

How is it a nuisance to get 2 way switching right. Electrical work itself can be a nuisance anyway.

Having said all this, i would use control circuits to light switching positions if it was up to me. It is easier to wire too i believe. A lot simpler.

ecenur

2011 wrote: »

Yes I know what you mean.

I have also seen electricians with only industrial experience trying to do domestic. They are very different areas. IMHO the qualifications should be more specific as to what type of electrician someone is. There is a world of difference.

I strongly agree with what you are saying, I am looking for electricians to fix a couple of my lighting problems. I want an electrician who knows what they are doing at all times and really does provide excellent service for the money you are giving them but then again every electrician is different and so are their qualifications.

Bruthal

ecenur wrote: »

I strongly agree with what you are saying, I am looking for electricians to fix a couple of my lighting problems. I want an electrician who knows what they are doing at all times and really does provide excellent service for the money you are giving them but then again every electrician is different and so are their qualifications.

Best get a domestic electrician so, no other could fix lights:D