EICR code opinions

radiohead · Jan 24, 2020

Currently doing an EICR, query concerns a distribution circuit to a pool plant room around 200m from the intake. Supply is TNS and a TPN SWA is fed from a 63a type D underground to the pool plant. At the plant room the SWA is terminated into plastic trunking with a separated TT system taking over. Issue is that the measured Zs on the armouring exceeds the max for the OCPD,(by some way), and hence the 5s disconnection time is not met (for the sub). Now normally such an issue would get a code 2, but given that nowhere is the gland or armouring accessible without actually removing the shroud would a code 3 be appropriate?
Changing to a type C would remain over, and although a type B would get over it, with two heat pumps amongst other high inrush gear it would not be practical. Only solution would seem to be a time delay RCD at source, but there is nowhere to put one. I'll have to sort it and a code 3 means it wont need sorting!! Opinions welcomed.

Risteard · Jan 24, 2020

If the armour is pierced then ADS won't be assured so I would suggest that it is an incorrect design.

radiohead · Jan 24, 2020

Risteard said:
If the armour is pierced then ADS won't be assured so I would suggest that it is an incorrect design.

I know it's an incorrect design, but what code would you apply....2 or 3 ?

westward10 · Jan 24, 2020

Depends how you consider disconnection times not being met, urgent or a recommendation of improvement. ADS is a fundamental requirement for safety.

JBW175 · Jan 24, 2020

Seems like you’re after a kop out. Just remember it’s your name on the bottom of that report.

I always code accordingly and advise on what remedial action I think is required, It helps me sleep at night.

radiohead · Jan 24, 2020

JBW175 said:
Seems like you’re after a kop out. Just remember it’s your name on the bottom of that report.

I always code accordingly and advise on what remedial action I think is required, It helps me sleep at night.

Couldn't be further from the truth. The very reason I am asking opinions is so the code is correct. It's debatable whether a disconnection time of (say) 10 seconds (because of a higher than permitted Zs) is potentially dangerous when 5 seconds is not, for a conductive part that is not accessible to touch. At least indirectly you have given away your view that it's a code 2. I have left the info and BB back at the office, but next week I think I will calculate the actual disconnection time which may influence the code I apply.

davesparks · Jan 25, 2020

I would say it is a C2 for the high EFLI and a C3 for the selectivity issue.

It may be possible to cure both by protecting it with fuses rather than an MCB

radiohead · Jan 25, 2020

Thanks for the replies, I lean towards code 2, it's a merlin geran DB so fuses would not be any more practical than a standalone T/D RCD.

GBDamo · Jan 25, 2020

radiohead said:
Currently doing an EICR, query concerns a distribution circuit to a pool plant room around 200m from the intake. Supply is TNS and a TPN SWA is fed from a 63a type D underground to the pool plant. At the plant room the SWA is terminated into plastic trunking with a separated TT system taking over. Issue is that the measured Zs on the armouring exceeds the max for the OCPD,(by some way), and hence the 5s disconnection time is not met (for the sub). Now normally such an issue would get a code 2, but given that nowhere is the gland or armouring accessible without actually removing the shroud would a code 3 be appropriate?
Changing to a type C would remain over, and although a type B would get over it, with two heat pumps amongst other high inrush gear it would not be practical. Only solution would seem to be a time delay RCD at source, but there is nowhere to put one. I'll have to sort it and a code 3 means it wont need sorting!! Opinions welcomed.

How old are the heat pumps, most are inverted nowadays.

davesparks · Jan 25, 2020

radiohead said:
Thanks for the replies, I lean towards code 2, it's a merlin geran DB so fuses would not be any more practical than a standalone T/D RCD.

It may not be more practical, but it would be a better solution in my opinion if it solves the Zs issue.
A standalone RCD would not help with the selectivity issue.

radiohead · Jan 25, 2020

GBDamo said:
How old are the heat pumps, most are inverted nowadays.

They look recent.
[automerge]1579983668[/automerge]

davesparks said:
It may not be more practical, but it would be a better solution in my opinion if it solves the Zs issue.
A standalone RCD would not help with the selectivity issue.

I'd prefer to keep a device that disconnects all 3 phases at source rather than risk a loss of one phase, there are several 3 phase motors, including a very costly borehole pump installation, last time that failed I'm informed the bill was around 10K.

davesparks · Jan 25, 2020

radiohead said:
They look recent.
[automerge]1579983668[/automerge]

I'd prefer to keep a device that disconnects all 3 phases at source rather than risk a loss of one phase, there are several 3 phase motors, including a very costly borehole pump installation, last time that failed I'm informed the bill was around 10K.

You'd prefer to leave a C2 and C3 in place when it can be corrected because of a fear of loosing a phase, which shouldnt cause damage if the motors are correctly protected?
I may be wrong but I thought each motor had to have its own, correctly set, overload protection which will operate should a phase be lost from the supply,amongst other things?

Drackley · Jan 25, 2020

C2 sleep well zzz

radiohead · Jan 26, 2020

davesparks said:
You'd prefer to leave a C2 and C3 in place when it can be corrected because of a fear of loosing a phase, which shouldnt cause damage if the motors are correctly protected?
I may be wrong but I thought each motor had to have its own, correctly set, overload protection which will operate should a phase be lost from the supply,amongst other things?

I didn't say I'd leave a code 2 in place, I've already stated my preferred solution is a T/D RCD at source which will satisfy earth fault protection and disconnect all 3 phases, there is not much space but I'll have to get it in somehow. The agreed extent of the EICR is only the main building and distribution circuits fed from the main building. The pool plant room is under a maintenance contract and under the supervision of others. Whether or not there is overload protection to motors is not my concern.

davesparks · Jan 26, 2020

radiohead said:
I didn't say I'd leave a code 2 in place, I've already stated my preferred solution is a T/D RCD at source which will satisfy earth fault protection and disconnect all 3 phases, there is not much space but I'll have to get it in somehow. The agreed extent of the EICR is only the main building and distribution circuits fed from the main building. The pool plant room is under a maintenance contract and under the supervision of others. Whether or not there is overload protection to motors is not my concern.

If fuses comply from a Zs point of view then they will provide a better solution. To put the whole plant room onto one RCD seems like a recipe for trouble with regards nuisance tripping. Have you measured the earth leakage when the plant is operational and/or when it is starting up?

Will the upfront RCD comply from a selectivity point of view?

radiohead · Jan 26, 2020

davesparks said:
If fuses comply from a Zs point of view then they will provide a better solution. To put the whole plant room onto one RCD seems like a recipe for trouble with regards nuisance tripping. Have you measured the earth leakage when the plant is operational and/or when it is starting up?

Will the upfront RCD comply from a selectivity point of view?

The whole plant room is already on one RCD, a wylex 100a four pole 30ma (4293) on the incomer in the plant room. It's separated to a TT at that end. I'm informed it rarely trips. A 100ma T/D at source will protect the SWA conductive parts and meet selectivity requirements, AND drop all 3 phases in the event of an earth fault on the sub.