4 pole socket for boiler ?

[SimonH2]

In the past, I've come across* a few commercial heating installations where the pumps are connected with plugs (often a 16A BS4343, aka "commando"). Makes sense as it avoids having the heating fitter have to do anything with the fixed wiring if they have to change a pump out.
At church, I had to diagnose a problem with the heating - blowing fuses and tripping the upstream MCB. The last person to do any wiring used cooker connection units for pump and boiler - so I had to disconnect wiring to isolate them. Turned out to be a faulty frost stat which passed IR tests @ 500V but "popped" when power applied to the system
Some changes to the system are needed, and I was thinking about plugs & sockets ...
The boiler is very basic at the moment - no permanent live, just apply power and it fires up. But since most boilers need both a permanent and switched live, that would mean a 4 pole plug & socket. Other than the Klix designed for emergency lighting, I can't think of anything that wouldn't be "misuse" - eg using a red BS4343 socket might lead to confusion.

It does need to be something that the "average" heating system engineer or plumber will understand

* Often the data cabinets are stuck in a services room/cellar along with the boilers etc. In one case, I was installing a network connection for a new building management system to connect to.

 

[333rocky333]

Why a red commando plug, they are for 3 phase, blue is for 240v and available in 4 pin

 

[AndyPRK]

Reminds me I was going to use bulgin 8 pin sockets for motorised valves once.

 

[ericmark]

The military have used this idea for years, alternators, starter motors all plug in, so if you have a hundred churches to look after having plugs and sockets for water pumps, motorised valves, etc. Would mean far quicker repairs.

But not really an advantage with just one church.

 

[SimonH2]

Why a red commando plug, they are for 3 phase, blue is for 240v and available in 4 pin

Red is for 415V (and similar) - and not necessarily 3 phase, there's a red 3 pin (1P+N+E) plug/socket.

Any mainstream vendors offering other than 3 pin in blue ? Or more correctly, anyone offering both a plug and a socket ? So far I've found that CPC have a 5 pin blue plug (MK Commando) but apparently no socket, and they have a 4 pin socket (different make) but apparently no plug.
But then I think the blue 5 pin would be as "wrong" and the red 5 pin. A blue 5 pin is defined as 120-208V P-N and 144-250V P-P, while the red one is what we are used to (415 P-P and 240 P-N, ish). So using a blue one would be "wrong" in having 240V P-N; and a red one would be wrong in having nothing between two phase pins, while correctly having 240V P-N on two pins. A 4 pin plug (of either colour) would also be "wrong" in having one "phase" pin as neutral.

https://en.wikipedia.org/wiki/IEC_60309

I think that purely on the basis of availability, using other than a 3 pin blue or 5 pin red "commando" plug/socket would be a non-starter.

But not really an advantage with just one church.

Indeed, not much of an advantage. Might just change the connection plates to switches - with indicator lights to make it easier to see what's supposed to be running.

 

[333rocky333]

I am sure theres not a 3 pin Red , theres a 4 pin for 3 phase motors with no neutral.
Tlc sell Blue 4 pin plugs and sockets.
The switch indicator could be a possible hazard due to the power re energising via a remote external source making safe isolation to the switch potentially hazardous

https://www.tlc-direct.co.uk/Main_I...dex/MK_Commando/index.html#MK_Commando_240_16

 

[SimonH2]

I am sure theres not a 3 pin Red , theres a 4 pin for 3 phase motors with no neutral.
Tlc sell Blue 4 pin plugs and sockets.

So they do, but if you look at the PDFs linked to, you'll see that the same range includes 2P+E in red. I think it's probably safe to say that they are rarer than the 4 pin blue ones.

The switch indicator could be a possible hazard due to the power re energising via a remote external source making safe isolation to the switch potentially hazardous

Not really - there's only one supply to the system, so normal safe isolation techniques would be to switch that off and pull the fuse (it's a switched FCU). Switching off the pump or boiler switch would also do to isolate the single device - but then there'd be no means of locking it off. The indicators would only be there to show that (eg) the pump should be running - easier than listening to see if it's making the right noise.
Of course, one advantage of a plug & socket is that you can get a very distinct and visually observable isolation by pulling the plug

 

[EFLImpudence]

I'll try in the correct thread -

Can you not use a four-pole in-line plug and socket?

 

[bernardgreen]

My favourite range of connectors was the Mini Bucanneer range

Introduction to them click HERE

Shells come separately. Chassis and cable mounting types available

 

[ban-all-sheds]

So far I've found that CPC have a 5 pin blue plug (MK Commando) but apparently no socket, and they have a 4 pin socket (different make) but apparently no plug.

Surely that's just a bizarre situation created by hard-of-thinking buyers?

It would seem unlikely that MK would make a plug for a socket which they don't make, let alone for one which nobody makes.

But then I think the blue 5 pin would be as "wrong" and the red 5 pin. A blue 5 pin is defined as 120-208V P-N and 144-250V P-P, while the red one is what we are used to (415 P-P and 240 P-N, ish). So using a blue one would be "wrong" in having 240V P-N; and a red one would be wrong in having nothing between two phase pins, while correctly having 240V P-N on two pins. A 4 pin plug (of either colour) would also be "wrong" in having one "phase" pin as neutral.

Are those definitions of how they must, and may only, be used, or what they are rated for? I can't help but observe that plug and socket pins and contacts don't know what they are being used for.

https://en.wikipedia.org/wiki/IEC_60309

Full of words and phrases such as "preferred" and "rated voltage".

I think that purely on the basis of availability, using other than a 3 pin blue or 5 pin red "commando" plug/socket would be a non-starter.

I think you can use whatever you like as long as it does not contravene standards of construction.

It does need to be something that the "average" heating system engineer or plumber will understand

I would suggest that if the engineer cannot understand that the 4-pin plug plugs into the 4-pin socket then a new engineer should be obtained.


Overall I must be missing something fundamental - I can't foresee any problems.

 

[flameport]

plugs & sockets

This: https://www.plumbase.co.uk/5-way-connector-block-rege105-10000214-3530924
and the 3 way version: https://www.plumbase.co.uk/rege103-3-way-connector-block-10000601-3530920
both designed for use on heating systems.

Makes sense as it avoids having the heating fitter have to do anything with the fixed wiring if they have to change a pump out.

Fixed wiring or not, replacing a component requires making the exact same connections.
The only difference is 1 - connections being in a socket or 2 - in something fixed to the wall.
If someone can't manage 2, then they can't manage 1 either and should not be working on wiring of any sort.

 

[SimonH2]

Surely that's just a bizarre situation created by hard-of-thinking buyers?

Yes, and not the only one they have

Are those definitions of how they must, and may only, be used, or what they are rated for?

They are the voltages they should be used for - basically so you know that if you have (say) a 5 pin red plug, it's safe to plug it into a 5 pin red socket. So if you had (for example) a 3wire, 3phase, 240V P-P bit of kit - you must use a blue plug as fitting a red plug would allow someone to feed it with 415V P-P and let the magic smoke out Similarly, you must not put a blue plug on a 110V single pahse device, or a yellow socket on a 240V supply.

I think you can use whatever you like as long as it does not contravene standards of construction.

Yes and no. it would be exceedingly bad practice to use something which easily allows incompatible connections - such as putting a blue plug on a 110V device. The blue plug would be well within it's ratings and thus, by your definition, OK - but it would be crazy to use a blue plug because a typical user would then expect it to be OK to plug into any blue socket. That is the reason that these plugs/sockets are coded with colour (to make it easy for users to match them) and keyway-earth pin orientation (to make mis-mating impossible).
For that reason, I reckon the safest option would be a red socket - as that's intended for 240V P-N even if it's not (in this application) 415V P-P or even multi-phase at all.

I would suggest that if the engineer cannot understand that the 4-pin plug plugs into the 4-pin socket then a new engineer should be obtained.

That's not the hard part - it's having someone understand that a 4 or 5 pin socket isn't 3 phase. Plumbers and heating (so called) engineers seem quite capable of finding interesting ways to get things wrong :

While I was diagnosing the problem I mentioned, I found that the neutral of the FCU wasn't actually in the supply - the person wiring it up had got his blacks mixed up so the neutral of the supply was permanently connected to everything except one device which was fed via the isolator. Took me a while to realise why there was a hard fault between neutral and earth with the neutral isolated & even removed from the FCU
Also, there's a non-return valve in the feed pipe from the F&E tank which I imagine was put in to avoid a pumping over problem - but it causes the expansion go go out through one of the vent pipes* and dribble outside, to be made up with fresh water when the system cools

* There's some of the old big cast iron radiators and a lot of big cast iron pipes, and in common with many such installations, they've put vent pipes on the rads so they self vent to outside rather than having to be manually bled. This means that the pump can draw down water from the system and pump it into the F&E tank via the feed pipe.

AFAIK I'm the only one with any technical knowledge or skills to be on the PCC for many years - hence everything has been left to "the specialists" to do whatever they say is right. It could take a while to find all of the "interesting" features.

 

[Simon35]

Mennekes supply all combinations of colours and pins, I used them for some 5 pin blue plugs and sockets recently. That was for 200V line voltage.

 

[333rocky333]

For that reason, I reckon the safest option would be a red socket - as that's intended for 240V P-N even if it's not (in this application) 415V P-P or even multi-phase at all.

Sorry , still unsure why you say that red is safer than a blue plug, i appreciate its not in an environment where 3 phase equipment could be plugged in
Not sure why you stated 208 volt P to N for a blue socket, I believe its 250 v

 

[333rocky333]

Mennekes supply all combinations of colours and pins, I used them for some 5 pin blue plugs and sockets recently. That was for 200V line voltage.

Yes mennekes stuff is lot cheaper than Mk and Lewden