SP/DP RCBO's for domestic .Do you have a preference ?

[LukeD]

Ive seen a few guys happy to fit both and a couple of others who only fit DP's . Do you have a preference ?

 

[stevethesparks]

Now available at a reasonable price DP all the way - cant see a reason not to.

 

[LukeD]

Now available at a reasonable price DP all the way - cant see a reason not to.

True....the drop in price is amazing .

 

[timhoward]

Preference will always be DP so
Neutral - earth faults are localised.

 

[davesparks]

I haven't done much domestic in years, is there now a readily available option for CUs that accept SPSN or DP devices?

My preference when I was doing more domestic was to use SPSN RCBO's when possible.

 

[nicebutdim]

I haven't done much domestic in years, is there now a readily available option for CUs that accept SPSN or DP devices?

My preference when I was doing more domestic was to use SPSN RCBO's when possible.

A number of manufacturers now offer SPSN RCBOs, with some doing so at very reasonable prices.

 

[timhoward]

I haven't done much domestic in years, is there now a readily available option for CUs that accept SPSN or DP devices?

Fusebox brand. It’s very good

 

[Mike Johnson]

Only option in Europe is DP we will eventually catch up.

Ohh do I dare say and use radials only and no loop in lighting.

 

[davesparks]

Only option in Europe is DP we will eventually catch up.

Ohh do I dare say and use radials only and no loop in lighting.

What do you mean by catch up? What in our electrical systems requires DP protection? Mainland Europe requires DP protection due to the differences in our systems.

 

[Mike Johnson]

Now how did I know it was going to be you that questioned my post.

 

[davesparks]

Now how did I know it was going to be you that questioned my post.

I don't know, but I am interested to know what exactly it is we need to 'catch up' with?

We have LV distribution which has a reliably earthed neutral so why would we need DP protection?

I fully support the use of SPSN residual current protection but I see no need for DP protection.

 

[LastManOnline]

What do you mean by catch up?

He is referring to the advantages of DP rcbo,s over single pole.

What in our electrical systems requires DP protection?

While it may not be a requirement ,it is always a benefit for final circuits to have DP isolation.

Mainland Europe requires DP protection due to the differences in our systems.

Mainland Europe uses the same electrical systems as the UK.

 

[davesparks]

He is referring to the advantages of DP rcbo,s over single pole.

While it may not be a requirement ,it is always a benefit for final circuits to have DP isolation.

Mainland Europe uses the same electrical systems as the UK.

DP rcbos don't have an advantage that is not also offered by SPSN RCBO's in the UK.

What is the benefit of DP protection in a system which had a reliably earthed neutral?

Mainland Europe does not have the same electrical system as the UK. For example their general purpose connector systems do not have polarity, whereas ours do.

As I have said may times one here I support the use of SPSN residual current protection, but I see no reson for DP protection generally.

I don't like this idea that 'DP is better than SP' without having a good supporting argument. Years ago in the UK DP protection was the standard because it was necessary, but we improved our electrical systems so that it is no longer required.

 

[timhoward]

As I have said may times one here I support the use of SPSN residual current protection, but I see no reson for DP protection generally.

i agree there is no need for over current protection on the Neutral unless it’s a specialist installation.
We also need to throw into the mix that several manufacturers call RCBOs double pole for ease when they are actually SPSN in reality.
There could therefore be terminology confusion here too.

 

[Mike Johnson]

I think its Double pole vs Double module that cause's the confusion.

 

[LastManOnline]

Welcome back by the way

DP rcbos don't have an advantage that is not also offered by SPSN RCBO's in the UK.

Iyou don't consider been able to isolate a neutral to earth fault on a final circuit a disadvantage ?
You don't consider been able to carry out an IR test on a final circuit without first having to disconnect a disadvantage ?
SPSN rcbo,s generally contain more electronics than their DOP equivalent.
I suspect that DP (and double module) rcbo,s dissipate heat better.
The single advantage I see SPSN having is the need for less space.Otherwise I see only disadvantages

What is the benefit of DP protection in a system which had a reliably earthed neutral?

See the above

Mainland Europe does not have the same electrical system as the UK.

Mainland Europe shares TNC-S and TT systems which are the two most widely used systems in the UK

I don't like this idea that 'DP is better than SP' without having a good supporting argument.

We are all entitled to personal opinion.But I can assure you that if you carried out more work in the domestic sector you would find DP rcbo,s make your life and the customers life considerably more convenient

Years ago in the UK DP protection was the standard because it was necessary, but we improved our electrical systems so that it is no longer required.

What are these "improvements" specifically?

 

[nicebutdim]

SPSN rcbo,s generally contain more electronics than their DOP equivalent.
I suspect that DP (and double module) rcbo,s dissipate heat better.
The single advantage I see SPSN having is the need for less space.Otherwise I see only disadvantages

Dissipation of heat isn't generally an issue in domestic installations. It shouldn't be an issue at all if breakers are arranged in such a manner that circuits drawing high loads are kept separate from each other - eg. not placing shower and kitchen socket circuits next to each other, but that's good practice regardless of breaker size.

While there may be advantages to having double module breakers, in a domestic environment these are outweighed by constraints on space. In fact I generally see single module RCBOs in commercial and industrial environments, without any issues arising from heat.

I wonder if statistics exist to highlight different rates of failure between single and double module RCBOs., but I honestly wouldn't expect a higher rate of failure from single module units.

Is there any advantage to having double module DP as opposed to single module SPSN or would such a move be the equivalent to 'upgrading' to CRT televisions and 1980s sized cell phones?

 

[happysteve]

I suspect there's some confusion about RCBO terminology going on here.

I suspect some folk regard SPSN = single pole switched neutral.

I suspect some folk regard SPSN = single pole solid neutral.

I suspect some folk couldn't convincingly tell you the difference between single pole switched neutral, and double pole.

I suspect I'm in this category. If I had to hazard a guess, it would be that the RCD side of things doesn't care which is the line, and which is the neutral (as the device is measuring a difference between the two), but that overcurrent is determined by what flows through the line only. Whereas a double pole device could detect overcurrent in either line or neutral. But that's only a guess. Happy to be schooled, though

 

[nicebutdim]

I suspect there's some confusion about RCBO terminology going on here.

I suspect some folk regard SPSN = single pole switched neutral.

I suspect some folk regard SPSN = single pole solid neutral.

I suspect some folk couldn't convincingly tell you the difference between single pole switched neutral, and double pole.

I suspect I'm in this category. If I had to hazard a guess, it would be that the RCD side of things doesn't care which is the line, and which is the neutral (as the device is measuring a difference between the two), but that overcurrent is determined by what flows through the line only. Whereas a double pole device could detect overcurrent in either line or neutral. But that's only a guess. Happy to be schooled, though

As an apprentice I'm ready to be shot down but, as RCDs & the RCD element of RCBOs detect imbalance between line & neutral, it matters not which side current is leaking from. What matters is the detection of imbalance above a predetermined level.

DP isolates both poles, SP isolates line only and SPSN (single pole switched neutral) is a single pole device which also switches neutral - to all intents and purposes the latter isolates both poles, but it is the manner in which this happens that differentiates between DP & SPSN. I've read details on this forum about how the latter works, but can not recall sufficient detal to offer a concise explanation. I suspect @pc1966 might fill in the blanks.

 

[loz2754]

@happysteve is correct.

A single pole switched neutral RCBO does indeed switch both poles when operated (either by residual current detection, or by overcurrent).

The difference between a SPSN RCBO and a DP RCBO is that the SPSN only reacts to an overcurrent that occurs in the line, and not the neutral, whereas a DP RCBO reacts to an overcurrent in either the line or the neutral. The result is the same though, as both poles are isolated when the device operates.

With a single pole RCBO, the neutral is connected straight through, and will possibly cause upstream devices a headache in the event of a neutral to earth fault.