Polarity

[m4tty]

Hi,

When carrying out Polarity tests, the centre contact of Edison screw lamp holders should be connected to the phase conductor with the exception of E14 & E27.

I understand why phase must be connected to the centre contact but why are E14 & E27 different?

Thanks

Matt

 

[Badger]

Hi,When carrying out Polarity tests, the centre contact of Edison screw lamp holders should be connected to the phase conductor with the exception of E14 & E27.

I understand why phase must be connected to the centre contact but why are E14 & E27 different?

Thanks

Matt

as far as im aware they should be treated the same ie phase conductor to the middle of the lamp not to the outer threaded area

 

[septiclecky]

I got told by a lecturer it was to do with being able to put you finger in it (BS finger test), fine I said a E14 is a small edison screw which may be hard but a E27 is a normal edison screw which you can get your finger in he could not give me an answer. :|

 

[Colonel Hathi]

I believe that these types are insulated differently (?)

CH

 

[PBC_1966]

I understand why phase must be connected to the centre contact but why are E14 & E27 different?

First I've heard of it. As far as I'm concerned, if you are connecting an ES lampholder - of any type - to a feed which has one supply conductor earthed, then the earthed side of the supply should be connected to the screw shell (or the equivalent contact which connects to the lamp screw-shell base for holders which don't actually have a metallic shell).

 

[Risteard]

It's for certain insulated types of E14/E27 Edison Screw lampholders. As such the threads will not be connected to the line conductor and as such does not pose a risk when changing the lamp with the switch closed.

 

[a1]

I believe that these types are insulated differently (?)CH

I do believe that you are correct.

It has to do with Insulation. I read it somewhere before.

 

[Lurch]

As above, E14 and E27 to BSEN60238 have a different design and as such the outer thread can be used as phase or neutral. There's some confusion as to exactly how this is achieved, but it's usually an insulated thread on the BSEN60238 compliant lampholders with the contact only being at the bottom of the thread.

Anyone guessing and saying E14 and E27 should be treated the same as any other ES lampholder should do some research before stating incorrectly that you can;t.

 

[PBC_1966]

Yes, there are types of ES lampholder where the screw shell is not directly connected to one side of the circuit, and the lamp base will be shrouded and not touchable before it makes connection with the contact.

But have the Regs. been amended to say that such lampholders may be connected either way round though? If so, when? There never used to be any such exception, just a requirement that all ES holders be wired with the phase to the center contact.

 

[Risteard]

with the contact only being at the bottom of the thread.

That's right. You'll see two contacts at the bottom instead of just the one.

 

[Lurch]

But have the Regs. been amended to say that such lampholders may be connected either way round though?

559.6.1.8

No idea when it was added\amended.

 

[PBC_1966]

559.6.1.8

Thanks, must have missed those exceptions somewhere allong the line.

They certainly didn't exist in the 14th, and I don't have a copy of the 15th to hand at the moment, but I'm pretty sure they weren't in that edition either. So I guess sometime during the 16th/17th.