PIR Sensor + Two core & earth (uninsulated)

[norm360]

I've got a PIR sensor I'm wiring outside.

It has connections for L / N / L1 (Switched live)

The cable I have is only two core + earth (uninsulated). I wired the earth core to neutral on the sensor, obviously I will connect it to neutral at the other end.

Is this potentially unsafe though, if water touched the neutral core could it pose a shock hazard?

 

[JohnW2]

I've got a PIR sensor I'm wiring outside. It has connections for L / N / L1 (Switched live). The cable I have is only two core + earth (uninsulated). I wired the earth core to neutral on the sensor, obviously I will connect it to neutral at the other end. Is this potentially unsafe though, if water touched the neutral core could it pose a shock hazard?

I suspect you know the answer - namely that this is just not acceptable. It's bad enough (and generates lots of discussion) when people use three core flex (with a green/yellow-insulated 'earth wire') for this purpose in the way you describe, but when it'a an uninsulated 'earth wire' in 'twin+earth' cable, it's really just a no-no. You need either 3 core + earth cable or 4-core flex.

Kind Regards, John

 

[phatboy]

It is dangerous and foolish. If you even for a moment thought that was acceptable I don't think you should complete any further electrical work, and should get any previous work you have done inspected by a competent person.

The CPC is not rated to the same current capacity as the conductors, so it could become overloaded, melt and catch fire.

Also of course, THERE IS NOW NO EARTH TO THE DEVICE!!! Even if your device is double insulated, what if later on someone replaces it with one that isn't, not realising the person who fitted the cable was a cowboy?!

 

[JohnW2]

The CPC is not rated to the same current capacity as the conductors, so it could become overloaded, melt and catch fire.

That's not actually true of 1mm² T+E (which is very probably what the OP is using) but, that aside, and as I said above, I certainly agree that what the OP proposes is totally unacceptable.

Kind Regards, John

 

[Iggifer]

I'd be more bothered about the fact it's single insulated than the current capacity, as even 1.0mm would be enough to act as the neutral to a PIR (assuming the connections are tight!)

But the slightest nick in the cable is gonna expose that 'CPC' to the elements

 

[mikeyd]

Norm: As said above you need to change the cable.

Is the cable exposed outside or does the cable either go straight through a wall into the back of the PIR or in trunking? If it will be exposed to the elements in any way don't get normal domestic (three core + earth etc.) cable. Get some more advice first.

 

[norm360]

It is dangerous and foolish. If you even for a moment thought that was acceptable I don't think you should complete any further electrical work, and should get any previous work you have done inspected by a competent person.

Hold on, no need to berate me. I'm asking to see IF it was safe, or is that so reprehensible. Would you prefer people didn't ask at all?

Anyway, the PIR sensor is double insulated + IP44 rated and the outside part of the cable is only 15cm at most.

But I suppose best practice is to get some 3 core so I will. Thanks for the replies.

 

[ban-all-sheds]

Hold on, no need to berate me.

Yes there is:

I wired the earth core to neutral on the sensor

Would you prefer people didn't ask at all?

Actually I'd prefer it if people learned about things beforehand, and acquired a full and genuine understanding of how it worked and exactly what to do before they picked up a screwdriver.

 

[mikeyd]

Actually I'd prefer it if people learned about things beforehand, and acquired a full and genuine understanding of how it worked and exactly what to do before they picked up a screwdriver.

I agree, but some people need to learn.

Often, telling them how it is makes them go away. This is a DIY forum. I would like to think we could steer the OP in the right direction, rather than scare them off.

No offense intended BAS, just a difference of opinion.

 

[ban-all-sheds]

I agree, but some people need to learn.

Exactly my point.

But the learning MUST come BEFORE the doing, not part-way through or afterwards

 

[bernardgreen]

BAS, part of education is telling people how much they need to know and why they need to know it. The next step is to teach them in a gentle way that does not induce resentment.

Yes the OP was wrong to even consider using the CPC for the neutral but he did not know how important the CPC is even if the appliance (lamp) does not require an earth.

 

[JohnW2]

BAS, part of education is telling people how much they need to know and why they need to know it. The next step is to teach them in a gentle way that does not induce resentment.

Indeed so.

Yes the OP was wrong to even consider using the CPC for the neutral but he did not know how important the CPC is even if the appliance (lamp) does not require an earth.

Again, indeed so - but it's worth pointing out that he clearly did feel the need to come here and ask the question (to which he quite probably suspected the answer) - and got an answer within 10 minutes.

Kind Regards, John

 

[norm360]

Actually I'd prefer it if people learned about things beforehand, and acquired a full and genuine understanding of how it worked and exactly what to do before they picked up a screwdriver.

The circuit never even saw any current, so regardless of how I wired it, I still took the necessary precaution to check its safety.

So your reproach is not only unhelpful, it's unwarranted.

It seems while a lot of decent folk are on this forum who are willing to assist and help, a certain few are more interested in using it as a platform to exert their superiority over a subject and denigrate others.

 

[EFLImpudence]

It seems while a lot of decent folk are on this forum who are willing to assist and help, a certain few are more interested in using it as a platform to exert their superiority over a subject and denigrate others.

A bit like the rest of the world.

 

[JohnW2]

It seems while a lot of decent folk are on this forum who are willing to assist and help, a certain few are more interested in using it as a platform to exert their superiority over a subject and denigrate others.

A bit like the rest of the world.

A lot like the rest of the world - and even more like the rest of the on-line forums/fora!

Kind Regards, John