Synchronous Clocks

Updated 14 January 2015.

Production of synchronous clocks started in the 1930s with the availability of alternating current mains electricity with accurately controlled frequency, and continued until the 1980s when they were increasingly superseded by quartz clocks. Some houses of that era have electrical sockets intended for synchronous clocks.

Their popularity was due to the fact that, providing the electricity supply was not interrupted, they kept good time, and did not need regular attention. Some models were self starting and were therefore ‘plug and run’. Others had to be started using a simple procedure. A synchronous movement runs continuously, so inertia is not a problem, and wheels are usually not crossed out. They were also relatively cheap, and when they stopped working were usually discarded. They are widely available on eBay and elsewhere. Although prices have increased in the last few years they are still cheap when compared with other types of clock.

Provided that the coil is intact, cleaning and lubrication is usually all that is needed to get a synchronous clock running, although the depredations of unskilled ‘repairers’ sometimes make this impossible. Wear sometimes makes starting unreliable. It is quite common to find that screws are missing. BA threads are normally used in British made clocks so replacement is straightforward. Replacement round and square clock glasses are available from horological suppliers. Otherwise new spare parts are not usually available. Used movements are sometimes available on eBay and elsewhere and hence are a possible source of spare parts.

As an example of the problems that can be encountered when servicing synchronous clocks, the Timlec synchronous mantel clock, described on the Timlec page, had six distinct faults, all of which had to be rectified in order to put the clock into good condition. Five of the faults were only accessible by dismantling the clock so were probably introduced by an unskilled ‘repairer’. A fixing screw for the back cover was missing. The tell tale that should have been visible through an aperture in the dial was missing. was missing. The clock is not self starting, and the starter did not work because a spacer was missing. The original terminal block had been replaced by a modern one, which was not attached to the movement. This is now attached to the movement by a suitable bracket. The dial was attached to the dial plate by four glued on pieces of corrugated cardboard, apparently in an attempt to simplify re-assembly. The extra thickness meant that the movement did not sit neatly in the case. The clock has a double worm reduction gear and the worms had been ‘lubricated’ with what appeared to be graphite grease so the movement did not run freely.

Unfortunately, ‘Nanny State’ regulations mean that servicing of synchronous clocks is not financially viable for professional clockmakers. Replacement synchronous movements are available, but installation of these makes clocks of less interest to collectors. Unfortunately, many synchronous clocks with good cases have had the synchronous movements replaced with quartz movements.

A selection of clocks by the makers listed in the sub pages is described briefly. These were mostly made for the UK market and, unless noted otherwise, are for a 230 V 50 cycles mains supply. Most British made synchronous clocks have motors which rotate at 200 rpm. One exception is Ferranti which rotate at 166⅔ rpm.

To view descriptions click a sub page, and follow a link in the sub page.


BIRD C. Metamec. The clockmaker. Dereham. Ticehurst, Sussex: Antiquarian Horological Society, 2003.

LINES M A. Ferranti synchronous electric clocks. Milton Keynes: Zazzo Media, 2012.

LINZ J. Westclox electric. Atglen, PA: Schiffer Publishing Co., 2004.

MILES R H A. Synchronome. Masters of electrical time keeping. Ticehurst, Sussex: The Antiquarian Horological Society, 2011.

NYE J. A  long time in making. The history of Smiths. Oxford: Oxford University Press, 2014

PHILPOTT S F. Modern electric clocks. Second edition. London: Sir Isaac Pitman & Sons Ltd, 1935.

POOK L P. British domestic synchronous clocks 1930-1980. The rise and fall of a technology. Springer, 2015.

RAWLINGS A L. The science of clocks and watches. Third Edition. Upton: British Horological Institute Ltd, 1993.

ROBINSON T R. Modern Clocks. Their repair and maintenance. Second edition. London: N A G Press Ltd, 1942.

SMITH B. Smiths domestic clocks. Second Edition. Herne Bay: Pierhead Publications Limited, 2008.

TRAN DUY LI. New Haven clocks and watches. Fairfax, VA: Arlington Book Co Inc, 1997.

WISE S J. Electric clocks. Second edition. London: Heywood & Company Ltd, 1951


10 Responses to “Synchronous Clocks”

  1. steve Says:

    Hi ,I have a Metamec electric clock,which is fitted with a lamp,which sits on top of the clock.
    It is a synchronous movement clock,which still keeps excellent time,unfortunately the alarm has ceased to function.
    I can not seem to find this model listed,and was wondering if maybe the lamp was added at some point .

  2. Les Pook Says:

    Metamec did make alarm clocks fitted with lamps, so the lamp on your clock was probably fitted at the time of manufacture. In some clocks the lamp flashed on and off when the alarm sounded.

  3. Gareth Says:

    Hi Les

    Do you have a record of how many times you have been asked about the availability of 2 amp, 2 pin connectors for clocks?

    The Plugs and Sockets etc (Safety) Regulations 1987 does allow for the possibility of approval of non-standard devices by a ‘specified person’ i.e. a standards inspector:-

    6.—(1) Subject to the following provisions of this regulation, any electrical device (other than a standard plug) specified in column 2 of Schedule 3 to these Regulations shall conform to the particular British Standard specified for such devices in column 3 ***or*** shall be of a kind approved by a specified person.

    7.—(8) Where an electrical device of the kind in question does not conform to a British Standard so specified and paragraph (7) above does not apply, no specified person shall approve a kind of electrical device ***unless samples of the device have been tested and the person is satisfied that such devices may reasonably be expected to be safe in use*** and is further satisfied, by inspection or testing, that the manufacturer of the device may reasonably be expected to ensure that normal production and design of the device will correspond with the samples.

    As 2 pin, 2 amp connectors were covered by the obsolete standard BS 372:1930 then no current standard would be applicable but if it could be designed to be ‘safe in use’ then it might be approved.

    I don’t know about you but i have seen some pretty horrendous ‘unsafe in use’ attempts to compensate for the lack of this connector.

    Do you think there would be a sufficient market to be worth pursuing even if it just covered costs?

    • Les Pook Says:

      I think this is a good idea. There is probably a sufficient market. I have never found a completely satisfactory work around and have seem some horrendous attempts. I don’t have a record of how many times I’ve been asked about replacement connectors, but it keeps coming up.

      There are two important points in the design of a replacement. The first is that it should incorporate a cable clamp to accommodate modern double insulated cable. Original connectors were designed for twisted pair cable. The second is that the shape must be such that it doesn’t foul the clock case. I have a Metalair connector that fits all the clocks of which I have experience, except Garrard clocks which have a different type of connector. TMC connectors will fit all clocks except some Metalair clocks and Garrard clocks.

      It might be worth approaching Maplin to see whether they could commission one of their suppliers to supply connectors.

      • Gareth Says:

        Having read thoroughly ‘The Plugs and Sockets etc (Safety) Regulations 1994’, the current standard, our connector would appear to be defined as the female half of an “appliance coupler” (i.e. not a plug, nor a socket) and therefore is not covered by the above regulations.

        As such, it would fall under the ‘Electrical Equipment (Safety) Regulations 1994’ which requires equipment be safe and well constructed. This also requires much documentation and that CE markings be applied.

        The appliance coupler approach seems correct as each manufacturer, Smiths, TMC, Gents, Goblin, etc had their own proprietory connector, based on the 2 amp plug pin spacing but the pin sizes varied in length and girth.

        According to the above guidance on, individual components of electrical equipment are not covered by the regulations and so it could be argued that the female coupler is merely a replacement of that component originally supplied with the clock when new. After all, the clock cannot function (safely) without it.

        I shall investigate further!

  4. Gareth Says:

    I have a variety of 2 amp 2 pin connectors, TMC, Smith, some 90° ones, a really compact one, half the length of the Smiths, but I’ve never seen a Metalair one. I have a Tempex clock with an aperture on the rear that is the same shape as, but too small for, the TMC. Would that be the same connector?

  5. Les Pook Says:

    No, the Metalair connector is not the same. It has an hourglass shaped cross section over most of its length (two cylinders connected by a web) with a corresponding aperture in the clock.

  6. Les Pook Says:

    You investigation of regulations looks promising.

  7. brian Simpson Says:

    Good Evening Les, I have read with interest your pages on synchronous electric clocks and note on your Tempo page you have recently corresponded. I chose this generic page because I have a glass advertising clock which I believe I purchased in Holland some years ago second-hand. The motor is in a plain drum like case of “plastic”, a sprung starter lever, a fine central rod which turns with motor possibly for hands setting and a triple mains (screw) connector marked: 110{220}150. The outside wires are connected, blue and black cable as it happens, probably confirming the continental purchase and I don’t think the threads are BA, tested that. I connected it yesterday and it keeps good time, there are no markings perhaps a manufactures logo on the glass which has faded; could you identify the motor/origin please. It is an advert for an English company possibly just post WWII. I have considered 3D printing a plug-socket. Brian

    • Les Pook Says:

      Brian. I don’t recognise the movement from your description. The marking on the connector is new to me. It is probably an unbranded, imported movement that was bought in cheaply by an advertising clock manufacturer. Les

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