Voltage Trips

[Knobhead]

As far as i can remember you needed to test those old VOELCB's with a dedicated tester, to get any meaningful result, as to there operating efficiency!! Haven't see one of those test kit's for years now, not even on Ebay!! ...lol!! To be honest, they have passed there sell by date, current balance breakers are by far the better arrangement. If variants of the voltage operated type are still being sold, it would i think be for specialised installations, you certainly wouldn't replace an existing unit with a new one!! lol!!

I remember our estates electrician had one. That’s going back 40 years.

 

[spark 68]

checking online I find many types of ELCB are still available, so they must still have a place in some installations.

Would these still have a use in say an IT system ?

 

[GLENNSPARK]

The old VO trips such as the chilton or crabtree worked on a voltage of 50V to earth. RCD's otoh work on imbalance in the current flowing in the live and neutral conductors. RCD's are much more sensitive, but can be problematic because of this. as far as I know all VO ELCB's are obsolete, but in my area (east Yorkshire) they are almost universal in village installations, and work very well. when these were installed we used to put a polythene insert in the incoming water supply to prevent parralell earth paths, and also make sure that all bonding went back to the CU earth terminal(and thus through the elcb operating coil). the most vunerable part of the installation is the connection to the earth spike, and the fact that in prolonged periods of dry weather the earth loop impedance may rise considerably. Although I have never seen a trip that, when tested, failed to operate in dry weather, cases of nuisance tripping caused by localised fault currents from other earth spikes do rise. There are probably hundreds of thousands of the Crabtree "Chilton" pattern still in use, and although they are now obsolete, the reports I hear that they are dangerous are mainly excuses which generate work and profit, and sometimes may leave a householder with less protection than they had before. I have had absolutely no problems with Crabtree trips of the early (black with red button) or later (grey with yellow button) types. There os however an older model made by Tenby (I think) that almost always has a burnt out trip coil (you can smell them from yards away!) they also emit a slight buzzing indicating that current is flowing to earth but because of shorted windings, it can't trip. These are dangerous and should be changed! checking online I find many types of ELCB are still available, so they must still have a place in some installations. see Earth leakage circuit breaker - Wikipedia, the free encyclopedia for more info.

yep...been out filey today....BS3036-6 way...TT=87.6 ohms.... crabtree VO ELCB....were gonna do away with the voelcb on second fix=test and put a stand alone RCD for the 3036 as its good for continued service .....

 

[Deleted member 9648]

Removed one in a farmhouse last week....unit inoperative,L-E fault on the D/S ring....Ra of 700 ohms.....everything connected to the 'earthing system' in the house live and giving shocks.

 

[Shaun1987]

Ive come across quite a few, some of them can be a real pain to reset.

 

[richy3333]

yep...been out filey today....BS3036-6 way...TT=87.6 ohms.... crabtree VO ELCB....were gonna do away with the voelcb on second fix=test and put a stand alone RCD for the 3036 as its good for continued service .....

What, you're gonna keep a 3036 board in use, no forced RCD board change, you'll have the Electrical Trainee's foaming at the mouths

 

[GLENNSPARK]

What, you're gonna keep a 3036 board in use, no forced RCD board change, you'll have the Electrical Trainee's foaming at the mouths

yes...but you do what needs to be done to ensure compliancy...nowt less.....and nowt more unless the person ordering the work asks for it....i have IR`d all final circuits being fed from that C/U...so i know when we introduce an earth leakage device into the mix there should be no nasty surprises.....:38:

 

[Guest123]

If you come across one of these VO ELCB units to BS 842 1965, when conducting an EICR, industry guidance suggests a minimum of a code 3 be attributed even if the device is found to be operating correctly.

If the install is old enough to still have one of these present, chances are the earth path may be still be via a metallic service pipe which would warrant a minimum of a code 2.


IMHO, even functioning units of this type are unfit for contiuned service and should be removed & replaced as a matter of course.


Early versions of the newer grey Chilton units were also VO ELCB's but soon changed to become ELCB's BS 4293 1968, these were early versions of the humble RCD. Care should betaken when identifying these, the simplest indicator is the rating of the unit, VO ELCB's will have 50V written on them ELCB's will have a mA rating.

 

[hermetic]

As I said, If you test with the units test button, AND by simulating a fault at the remote end of the installation ( which rules out parralell earth paths), they provide protection which is better than fuses alone. there are 1001 things a DIYer can do to render an installation dangerous. Someone mentioned touch voltage, they are irellevant in this case as as soon as the earthed metal starts to conduct a fault current, it trips the ELCB. Actually it is the same with an RCD as long as the metalwork is earthed, it will also trip.As I also said, the earth spike/connection needs to be maintained (as does all parts of any electrical system, remember "This installation should be periodically checked and tested" etc etc) You can mark anything down as "potentially dangerous" just as any human being is a potential murderer! I have seen many modern installations that I consider to be "potentially dangerous" not becuase they are badly installed or incorrectly specified, but because some of the modern equipment is so poorly made with exposed live parts, poorly fttting clamping screws,and dubious looking cable clamps that hardly look able to carry their rated current etc etc. Only time will tell if the RCD will be as reliable, and safe (and "fail safe") as everyone seems to believe it will be. whilst typing this, a thought occurs to me, it seems ok to subject a householder to a "touch voltage" to operate an RCD under certain circumstances, and yet there now seems to be an embargo on neon screwdrivers on HSE grounds...............just a thought. I have used a neon all my working life, and still do, the only time I ever got a belt of it was when one of my "mates" fitted a slightly smaller resistor............but I got my revenge on the B*****D
Phil

 

[GLENNSPARK]

As I said, If you test with the units test button, AND by simulating a fault at the remote end of the installation ( which rules out parralell earth paths), they provide protection which is better than fuses alone. there are 1001 things a DIYer can do to render an installation dangerous. Someone mentioned touch voltage, they are irellevant in this case as as soon as the earthed metal starts to conduct a fault current, it trips the ELCB. Actually it is the same with an RCD as long as the metalwork is earthed, it will also trip.As I also said, the earth spike/connection needs to be maintained (as does all parts of any electrical system, remember "This installation should be periodically checked and tested" etc etc) You can mark anything down as "potentially dangerous" just as any human being is a potential murderer! I have seen many modern installations that I consider to be "potentially dangerous" not becuase they are badly installed or incorrectly specified, but because some of the modern equipment is so poorly made with exposed live parts, poorly fttting clamping screws,and dubious looking cable clamps that hardly look able to carry their rated current etc etc. Only time will tell if the RCD will be as reliable, and safe (and "fail safe") as everyone seems to believe it will be. whilst typing this, a thought occurs to me, it seems ok to subject a householder to a "touch voltage" to operate an RCD under certain circumstances, and yet there now seems to be an embargo on neon screwdrivers on HSE grounds...............just a thought. I have used a neon all my working life, and still do, the only time I ever got a belt of it was when one of my "mates" fitted a slightly smaller resistor............but I got my revenge on the B*****D
Phil

and this is why i aint a believer in the `magic` 1667 ohms rule as a way of getting round high Zs....