Can you take 2 phases to a consumer unit?

[Pete999]

TP isolator in place of the RH DP switch (and labeled 'main switch'), links from N of isolator to each RCD, link from L2 of isolator to RH RCD, and link from L3 of isolator to LH RCD.
Both DP isolators removed and not used.
As things are at the moment you have a DP isolator (main switch) followed by another DP isolator (RCD) on each side of the board. The DP switches could have been omitted, and the supplies taken directly to the RCDs, each labeled 'main switch'.Feeding the two RCDs from a TP isolator gives a single point of isolation to keep everyone happy, however you interpret 'single point of isolation'.

So you would have 2 phases and 1 Neutral, could cause problems with a twin RCD board, don't you think?

 

[dksanders]

In my opinion, this board is absolutely fine as it is, as long as the PSC is confirmed as being less than the rating of the components. Anyone who has done any domestic installation outside of this small group of islands would be more than familiar with consumer units laid out like this.
The only change I would have made when fitting it, would have been to use a TP main switch instead of the two DP ones, but there's no requirement for this.

I think we've all seen the standard (or lack of it) of foreign electrical work abroad. Just because they do it, doesn't mean it's right or safe. That's why our Wiring Regs are often used as the yardstick to aspire to.

 

[Pete999]

I think we've all seen the standard (or lack of it) of foreign electrical work abroad. Just because they do it, doesn't mean it's right or safe. That's why our Wiring Regs are often used as the yardstick to aspire to.

Well said, Although our Cousins may choke on that point.

 

[Toneyz]

I would have prefered to see two S.P+N distribution boards eg DB 2 DB 3 but that's just me.

 

[Billsays]

The 3rd phase (L1) goes to a consumer unit downstairs. I think they have balanced the load.

So its 3 single phase supplies with a shared Neutral?

 

[Pete999]

I would have prefered to see two S.P+N distribution boards eg DB 2 DB 3 but that's just me.

No Mate you are right.

 

[brianmoooore]

So you would have 2 phases and 1 Neutral, could cause problems with a twin RCD board, don't you think?

No, I don't. Exactly the same as if it were two boards side by side on different phases. Only thing that could upset the RCDs is if the N section of the isolator became resistive, and if that happened, it's good that the RCDs draw attention to the problem.

 

[MFS Electrical]

I would say that unless its been ok'd by the manufacturer then it isn't right probably contravenes the standard that consumer units are built too because a domestic consumer unit isn't designed for two phases

 

[Toneyz]

I think that it can withstand 6KA?

 

[brianmoooore]

I think we've all seen the standard (or lack of it) of foreign electrical work abroad. Just because they do it, doesn't mean it's right or safe. That's why our Wiring Regs are often used as the yardstick to aspire to.

I see jingoism is alive and well on here!
I've seen excellent electrical installations both here and throughout Europe (maybe not Greece), and I've seen wiring that should be disconnected on sight in both.
I've done a lot of farm installations throughout my career, and was bringing in and using IP55 rated consumer units (fuseboxes, back then), complete with RCDs, when the nearest you could readily get in this country at the time would be open backed, wooden framed Wylex units with rewireable fuses. RCDs (if you could justify the bank loan to buy one) had to be mounted along side the fusebox, and were nearly the same size.
I could argue that continental wiring practices back then were far in advance of UK ones, and that it's only recently that we've caught up.

 

[Pete999]

No, I don't. Exactly the same as if it were two boards side by side on different phases. Only thing that could upset the RCDs is if the N section of the isolator became resistive, and if that happened, it's good that the RCDs draw attention to the problem.

What exactly do you mean by if the N section of the isolator became resistive? Are you saying if the N became a dodgy connection/ because that could happen to a DP switch just as easily. Doing what you propose could cause the "borrowed N syndrome" However you look at this situation, taking Two phasesinto what is, in reality, a Single Phase situation is inherently dangerous, in my opinion, is a dumb way of doing things.

 

[brianmoooore]

I have a split phase supply to my own property. 460V across L1 and L2, and a N to keep the mid point where it should be, and all through a Western Power supplied and fitted TP isolator. Most of the installation here is single phase on one phase or the other, and a few circuits connect to the 460V and the neutral. Things would get interesting if the neutral became disconnected, just as it would in a row of three houses in a street.
Reminded me of something I witnessed many years ago at a property that also had a split phase supply. A message had caught up with me asking me to attend the property because of electrical problems (intermittent short power drop outs), and I arrived just in time to see a REC employee disconnect the N from the incoming cut out assembly with the power still on. Load was very imbalanced at the time, with heavy power consuming equipment in use on the phase supplying the farm. Voltage on the phase supplying the farmhouse shot up to what I calculated to be around 400V, with the results you may expect.
REC tried to cover their tracks, of course, and told the householder to claim on their household insurance, but I had seen what I'd seen, and fought the case on their behalf. Ended up with just under £1000 in compensation.

 

[dksanders]

I see jingoism is alive and well on here!
I've seen excellent electrical installations both here and throughout Europe (maybe not Greece), and I've seen wiring that should be disconnected on sight in both.
I've done a lot of farm installations throughout my career, and was bringing in and using IP55 rated consumer units (fuseboxes, back then), complete with RCDs, when the nearest you could readily get in this country at the time would be open backed, wooden framed Wylex units with rewireable fuses. RCDs (if you could justify the bank loan to buy one) had to be mounted along side the fusebox, and were nearly the same size.
I could argue that continental wiring practices back then were far in advance of UK ones, and that it's only recently that we've caught up.

That's interesting to know, maybe the enforcement and compliance isn't as good as it is here (e.g. as comes by being a member of e.g. NICEIC (normally anyway))

 

[Gigsy]

TP isolator in place of the RH DP switch (and labeled 'main switch'), links from N of isolator to each RCD, link from L2 of isolator to RH RCD, and link from L3 of isolator to LH RCD.
Both DP isolators removed and not used.
As things are at the moment you have a DP isolator (main switch) followed by another DP isolator (RCD) on each side of the board. The DP switches could have been omitted, and the supplies taken directly to the RCDs, each labeled 'main switch'.Feeding the two RCDs from a TP isolator gives a single point of isolation to keep everyone happy, however you interpret 'single point of isolation'.

Great suggestion. I think this is exactly the advise I will give to the customer. Thank you.

 

[vitoboy]

Good stuff gigsy. .. we don't want rule of thumb ..we want to know why.

If there is no reg that's has been broken then any problem is the iee problem .. not ours.

Brian Moore .. good stuff.. Plymouth. .?